Zolpidem (Ambien): Independent Evidence on Insomnia, Side Effects & Withdrawal

Key takeaways
  • Zolpidem does help people fall asleep, but the effect is modest. An analysis of the trials submitted to the US FDA found Z-drugs cut sleep-lab sleep latency by about 22 minutes more than placebo; the authors called the drug and placebo effects "of questionable clinical importance" (Huedo-Medina et al., BMJ 2012).
  • It is a short-term medicine. In the UK it is usually prescribed for 2 days to 4 weeks because the body "gets used to" it and can become dependent on it (NHS). The UK product information says treatment should not exceed four weeks, including tapering (UK SmPC).
  • Since 2019, US labelling has carried a boxed warning: complex sleep behaviours such as sleepwalking and sleep-driving have caused serious injuries and deaths (FDA 2019).
  • In 2013 the FDA halved the recommended starting dose for women (10 mg to 5 mg) because of next-morning blood levels high enough to impair driving (FDA 2013). A later analysis disputes whether women face extra risk.
  • For people aged 65 and over, the American Geriatrics Society says to avoid Z-drugs (strong recommendation). It cites falls, fractures, delirium and motor vehicle crashes, and "minimal improvement in sleep latency and duration" (AGS Beers Criteria 2023).
  • Every major guideline puts cognitive behavioural therapy for insomnia (CBT-I) first. Drugs are an option only when CBT-I is not enough (European Insomnia Guideline 2023).
  • Evidence grade: Moderate for short-term benefit; Risk for long-term and older-adult use.

Independent evidence review · Prescription medicine

Zolpidem (sold as Ambien in the US and Stilnox in many other countries) is one of the most widely prescribed sleeping pills in the world. It helps people fall asleep a little faster for a few weeks, and that benefit is real but small. Against it sit dependence, next-day impairment and falls, and a rare but sometimes fatal risk of doing things while not fully awake. Regulators in both the UK and the US frame it as a short-term treatment. In the US, 2011 figures show about 39 million zolpidem prescriptions dispensed to about 9 million patients, 63% of them female (FDA 2013). The independent evidence supports brief use in carefully chosen adults. It does not support nightly use for months or years.

Best evidence for short-term help falling asleep (days to weeks) in adults with severe insomnia
Main risks complex sleep behaviours, next-morning impairment and driving, dependence and withdrawal, falls in older adults
Key rule lowest dose, shortest time, never with alcohol or opioids; CBT-I comes first
Safety first
Zolpidem is a prescription-only sedative. Do not start, stop or change your dose without talking to the prescriber. If you have taken it for more than about 4 weeks, stopping suddenly can cause withdrawal and rebound insomnia (NHS). Never combine it with alcohol. Take extra care with opioid painkillers or other sedatives: the combination can cause dangerous sedation, slowed breathing, coma and death (UK SmPC). Do not drive, cycle or use machinery if you feel drowsy the next day, and remember you can be impaired even when you feel fully awake (FDA 2013). If you do something while not fully awake after taking it, such as sleepwalking, driving or cooking, stop taking it and contact your doctor (FDA 2019). If someone has taken too much, or cannot be woken, or has swelling of the lips, tongue or throat, or trouble breathing, seek urgent help: call 999 in the UK, 911 in the US, or your local emergency number (NHS). Zolpidem can also worsen depression. Anyone having thoughts of suicide should seek urgent help (FDA Ambien label).

Table of contents

Evidence summary

Claim Evidence Source Funding / conflict Strength
Helps people fall asleep faster in the short term Across Z-drug trials in the FDA approval dataset, sleep-lab sleep latency fell by 22 minutes more than on placebo (95% CI 11 to 33). The effect was larger with higher doses and in older studies. In the Lancet network meta-analysis, zolpidem was among the drugs more effective than placebo for acute treatment, with standardised mean differences for the effective drugs in the range 0.36 to 0.83. Huedo-Medina et al., BMJ 2012; De Crescenzo et al., Lancet 2022 BMJ analysis: no funding, no conflicts. Lancet review: UK public (NIHR) funding; some authors have industry ties (see scorecard). Most of the underlying trials were run by manufacturers. Moderate
Keeps working over months For long-term treatment, eszopiclone beat zolpidem (SMD 0.60, 95% CI 0.00 to 1.20). Zolpidem caused more dropouts due to side effects than placebo (OR 2.00). Certainty was "very low" for every long-term comparison. De Crescenzo et al., Lancet 2022 NIHR-funded; author conflicts declared Insufficient
Better than CBT-I No. Adding zolpidem to CBT-I helped during the first 6 weeks. Remission at 6-month follow-up was higher in people who then stopped zolpidem and continued CBT than in those who kept taking it (68% vs 42%). Morin et al., JAMA 2009 Funded by the US National Institute of Mental Health; "not an industry-supported study". The lead author declared consulting for Sanofi-Aventis and others. Moderate
Complex sleep behaviours (sleepwalking, sleep-driving) These are rare but serious, and deaths have occurred. They can happen after the first dose, at recommended doses, and without alcohol. They led to a boxed warning in 2019. FDA 2019; FDA label US regulator (industry user fees fund much of FDA drug review) Risk
Next-morning driving impairment About 15% of women and 3% of men had zolpidem blood levels above about 50 ng/mL (a level that appears capable of impairing driving) 8 hours after 10 mg. In a cohort of 409,171 adults, new zolpidem use was linked to a higher risk of motor vehicle crashes (HR 2.20). FDA 2013; Hansen et al., AJPH 2015 FDA regulator data; university and Group Health authors (no funding statement found in the fetched text) Risk
Falls and fractures in older adults Z-drugs were associated with fractures (OR 1.63) and zolpidem with injuries (OR 2.05). In nursing home residents, hip fracture OR was 1.66, rising to 2.20 in new users. In people with dementia, the fracture HR was 1.40. Treves et al., Age Ageing 2018; Berry et al., JAMA Intern Med 2013; Richardson et al., HTA 2021 Berry: US National Institute on Aging. Richardson: UK NIHR. Treves: academic (funding not shown in the abstract). All are observational. Risk (consistent association)
Dependence and misuse The labels warn that the risk of dependence rises with dose and duration. In France, a rise in abuse cases led to stricter prescribing rules in 2017. After the change, reimbursed use fell by about 57%, but markers of problematic use persisted. UK SmPC; Aquizerate et al., Eur J Public Health 2023 French study: no funding; no conflicts declared Risk
Women need a lower dose FDA 2013: women clear zolpidem more slowly, so the recommended starting dose for women is 5 mg. A 2019 reanalysis confirmed 35% lower clearance in women, but found no on-road driving impairment at 8 hours and no clinical-trial evidence of extra risk to women. FDA 2013; Greenblatt et al., J Clin Psychopharmacol 2019 Regulator vs academic reanalysis (funding and conflicts not shown in the abstract we fetched) Contested

Independent evidence and credibility scorecard

Independence tier: 1 = no money from anyone selling the product; 4 = funded by the seller. Credibility: A (highest) to D.

Source Who funds it Country Independence tier (1–4) Credibility (A–D) Why it would tell the truth / residual bias
Huedo-Medina et al., BMJ 2012 No funding; no conflicts declared USA / UK 1 A Uses the FDA's own trial data, which reduces publication bias. Residual bias: the underlying trials were designed and run by the drugs' sponsors.
De Crescenzo et al., Lancet 2022 UK NIHR Oxford Health Biomedical Research Centre UK / Italy 2 A− A large, pre-registered review that included unpublished trials. Residual bias: the first author was employed by Boehringer Ingelheim, and the senior author leads Janssen-sponsored trials of seltorexant, a rival sleep drug in the same analysis (declared).
AASM guideline, Sateia et al. 2017 American Academy of Sleep Medicine USA 3 B Transparent GRADE methods. It downgraded evidence because most trials were industry-funded. Residual bias: some panel members declared industry consulting, and AASM itself receives support from companies that sell sleep medicines (not zolpidem specifically).
European Insomnia Guideline 2023 European Sleep Research Society; an NIHR grant is listed in the Europe PMC record Pan-European 2–3 B+ A consensus of 44 authors across many countries. Residual bias: we could not verify the individual authors' conflict statements (the publisher page was blocked).
AGS Beers Criteria 2023 American Geriatrics Society; "no sponsor for this paper" USA 1–2 A− Its purpose is to protect older adults. Residual bias: a few panel members consult for insurers or data firms, which could favour cheaper care; none has zolpidem-specific ties that we found.
US FDA (label, 2013 and 2019 safety actions) US government; about 77% of human drug review costs are paid by industry user fees (FDA PDUFA report FY2025) USA 2 B+ A legal duty, with access to raw data and post-marketing reports. Its safety actions here went against the commercial interest of the makers. Residual bias: dependence on user fees.
UK SmPC (MHRA-authorised) and NHS medicine pages The SmPC text is written by the licence holder (here Zentiva) and approved by the UK regulator; NHS pages are publicly funded UK 2 (NHS) / 3 (SmPC) B+ Legally regulated wording. Residual bias: SmPCs are company documents, although regulators must approve them. The NHS zolpidem pages were last reviewed in January 2023 and their review date (January 2026) has passed.
Berry et al. 2013, Richardson et al. 2021, Aquizerate et al. 2023 US NIA; UK NIHR; no funding (France) USA / UK / France 1 B Publicly funded safety research. Residual bias: all are observational, and confounding is possible because people prescribed sleeping pills may be frailer or sicker.
Kripke et al., BMJ Open 2012 Not stated in the abstract USA 2 C A large matched cohort. Residual bias: the lead author declared "long-term criticism of hypnotic drugs" on his website, and a family investment with small holdings in Sanofi-Aventis stock. Confounding is a serious concern.
Sanofi annual reports (Form 20-F) The company France 4 B for sales figures, D for product claims Securities law penalises misreporting sales. Product descriptions are promotional.

What zolpidem is

Zolpidem is a sleeping pill (hypnotic) from the "Z-drug" group, alongside zopiclone, eszopiclone and zaleplon. Chemically it is an imidazopyridine, not a benzodiazepine, but it acts at the same receptor site as benzodiazepines (UK SmPC). Brand names include Ambien and Ambien CR (US), Stilnox (France; marketed in over 100 countries) and Myslee (Japan). In the UK it is mostly dispensed as generic zolpidem tartrate. Other US zolpidem products include Edluar, Zolpimist and the low-dose Intermezzo (Sanofi 20-F 2012; FDA 2013).

Zolpidem was developed by the French company Synthélabo, which launched it in France in 1988 (Inpharma, March 1988). The FDA approved Ambien as a new molecular entity on 16 December 1992 under NDA 019908 (Drugs@FDA). Synthélabo merged with Sanofi in 1999, and the group is now Sanofi, headquartered in Paris (Sanofi 20-F 2012; Sanofi 20-F 2025).

Zolpidem is now a cheap generic medicine. Generics have been sold in Europe since 2004 and in the US since 2007 (immediate-release), and US generics of the extended-release form arrived in October 2010 (Sanofi 20-F 2010).

Legal status. In the UK zolpidem is "only available on prescription" (NHS). In the US it is a prescription medicine and a Schedule IV controlled substance under federal law (FDA label). France tightened its rules in April 2017 so that zolpidem must be prescribed on a secure prescription pad, as some narcotics are (Aquizerate et al. 2023).

How it works

Zolpidem boosts GABA, the brain's main calming chemical messenger. It is a positive modulator of the GABAA receptor and binds to the benzodiazepine site on receptors that contain the α1 subunit. This increases how often the receptor's chloride channel opens, which dampens nerve activity (FDA label).

Benzodiazepines bind several receptor subtypes. Zolpidem binds mainly the "omega-1" subtype. In animals this may explain why it has little of the muscle-relaxing and anticonvulsant effect that benzodiazepines have. All its effects are reversed by the benzodiazepine antagonist flumazenil (UK SmPC). This selectivity has been used to present Z-drugs as a safer alternative to benzodiazepines. In older adults, however, independent reviewers found adverse events similar to those of benzodiazepines (Beers 2023; Treves et al. 2018).

Timing in the body. Standard tablets reach peak blood levels in about 1.6 hours on average, with an average elimination half-life of about 2.5 hours (range 1.4 to 4.5) in healthy adults. Taking the tablet with or just after a meal lowers and delays the peak, so the label advises against doing so for faster sleep onset. Half-life is longer in older people. In liver cirrhosis the mean half-life was 9.9 hours, compared with 2.2 hours in healthy people (FDA label). The NHS says zolpidem takes around 30 minutes to work and "does not stay in your system for more than about 12 hours", although some people still feel sleepy the next morning (NHS).

What it is prescribed for

UK licence. Zolpidem is licensed for "the short-term treatment of insomnia in adults in situations where the insomnia is debilitating or is causing severe distress for the patient" (UK SmPC).

US licence. Ambien (immediate-release) is indicated for short-term treatment of insomnia with difficulty falling asleep. It was shown to shorten sleep latency for up to 35 days in controlled studies (FDA label). Ambien CR (extended-release) is indicated for short-term treatment of difficulty falling asleep and/or staying asleep (FDA Ambien CR label).

Where the guidelines place it:

  • NICE (England, TA77, 2004): use hypnotics only after non-drug measures have been considered, and "for short periods of time only". Because there is no compelling evidence to separate zolpidem, zopiclone and short-acting benzodiazepines, prescribe the one with the lowest purchase cost. If one does not work, do not try another (NICE TA77).
  • NHS: "GPs now rarely prescribe sleeping pills to treat insomnia". Sleeping pills are prescribed "for a few days, or weeks at the most" when insomnia is very bad and other treatments have not worked. CBT is offered first (NHS insomnia).
  • European Insomnia Guideline 2023: CBT-I is first-line for adults of any age (grade A). If CBT-I is not effective enough, benzodiazepine receptor agonists including zolpidem can be used for short-term treatment of 4 weeks or less (A). Longer use "may be initiated in some cases" after weighing the pros and cons (B) (Riemann et al. 2023).
  • AASM 2017 (US): "We suggest that clinicians use zolpidem as a treatment for sleep onset and sleep maintenance insomnia (versus no treatment) in adults." This is a WEAK recommendation, based on 12 trials whose overall quality was downgraded to very low (Sateia et al. 2017).
  • AGS Beers Criteria 2023 (adults 65+): avoid (moderate-quality evidence, strong recommendation). Also avoid in people with delirium, dementia or a history of falls or fractures (Beers 2023).

In short, zolpidem is a second-line, short-term option in every guideline we reviewed, and is not recommended for most older adults.

What works and what does not

Use or claim Verdict Evidence Key caveat
Falling asleep faster, short term (days to about 4–5 weeks) Works Beats placebo on sleep-lab and self-reported sleep latency in FDA trial data and in the Lancet network meta-analysis (BMJ 2012; Lancet 2022). The size of the effect is modest, and placebo response is large.
Short-term sleep quality and total sleep time Works AASM found moderately large improvements in sleep quality and improvements in total sleep time that exceeded its clinical thresholds for 10 mg (AASM 2017). Evidence quality was "very low" because of heterogeneity, imprecision and publication bias.
Staying asleep (fewer awakenings) Mixed Sleep-lab wake time after sleep onset fell meaningfully in two trials. Self-reported wake time and the number of awakenings fell below clinical thresholds (AASM 2017). The immediate-release US label covers only difficulty falling asleep.
Long-term nightly use (months to years) Insufficient Long-term comparisons all had "very low" certainty, with more dropouts from side effects than on placebo (Lancet 2022). The UK SmPC notes some loss of effect after a few weeks (UK SmPC). Dependence risk rises with duration.
Replacing CBT-I Not supported CBT-I effects "seemed to be sustained" (Trauer et al. 2015). Stopping zolpidem while continuing CBT gave the best long-term remission (Morin et al. 2009). A short course of zolpidem alongside CBT-I may help during the first weeks.
Being clearly better than other short-acting hypnotics Mixed NICE found no compelling evidence to distinguish zolpidem, zopiclone and short-acting benzodiazepines (NICE TA77). NICE's appraisal dates from 2004.
Children and adolescents Not supported A trial in 201 children aged 6–17 with ADHD-related insomnia failed to show benefit. Hallucinations occurred in 7.4% on zolpidem compared with 0% on placebo (UK SmPC). Not licensed under 18 in the UK.
Being "safe" in older adults because it is not a benzodiazepine Not supported Beers 2023 says Z-drugs have adverse events similar to benzodiazepines in older adults (Beers 2023). Falls and fracture data are observational but consistent.

Benefits by claim

1. Falling asleep: how many minutes?

The cleanest estimate comes from Huedo-Medina and colleagues. They analysed the data the manufacturers submitted to the FDA (13 studies, 4,378 participants, covering eszopiclone, zaleplon and zolpidem). Compared with placebo, Z-drugs reduced sleep latency measured in a sleep laboratory by 22 minutes (95% CI 11 to 33). The standardised effect on self-reported sleep latency was small (−0.33). Sleep latency was more likely to be reduced in earlier studies, with larger doses, with longer treatment, in younger and/or female patients, and with zolpidem. The authors concluded that the drug effect and the placebo response were "rather small and of questionable clinical importance", but that the two together produced a reasonably large clinical response (Huedo-Medina et al., BMJ 2012).

The UK product information gives trial-specific figures. In 462 healthy volunteers with transient insomnia, 10 mg reduced the average time to fall asleep by 10 minutes compared with placebo, and 5 mg by 3 minutes. In 114 patients with chronic insomnia, 10 mg cut it by 30 minutes and 5 mg by 15 minutes (UK SmPC). These are figures from individual sponsor trials, and pooled analyses are more reliable.

2. The placebo question

Placebo response in insomnia drug trials is large and shows up even on objective sleep-lab measures. A German meta-analysis of 32 trials (3,969 participants) estimated that 63.56% of the drug response was also achieved in placebo groups (Winkler & Rief, Sleep 2015). In practice, much of the improvement a person notices on zolpidem would probably have happened with a dummy pill and the expectation of help. The drug adds a modest amount on top.

3. Comparison with other drugs

The Lancet network meta-analysis covered 154 double-blind trials and 44,089 participants. For acute treatment it found that benzodiazepines, doxylamine, eszopiclone, lemborexant, seltorexant, zolpidem and zopiclone were all more effective than placebo (SMD range 0.36 to 0.83; high to moderate certainty). Benzodiazepines, eszopiclone, zolpidem and zopiclone were more effective than melatonin, ramelteon and zaleplon. The trade-off was tolerability: zolpidem caused more dropouts due to adverse events than placebo (OR 1.79, 95% CI 1.25 to 2.50; moderate certainty). Along with benzodiazepines, eszopiclone and zopiclone, it was also worse than placebo on the number of people with side effects (De Crescenzo et al., Lancet 2022). If you are weighing melatonin as an alternative, see our melatonin evidence review.

4. Long-term benefit

For long-term treatment, only eszopiclone and lemborexant beat placebo, both with "very low" certainty. Eszopiclone was more effective than zolpidem (SMD 0.60, 95% CI 0.00 to 1.20). Zolpidem had more dropouts due to side effects than placebo (OR 2.00, 95% CI 1.11 to 3.70; very low certainty) (Lancet 2022). One trial in the AASM review followed 91 people for 8 months (AASM 2017), but overall there is little good evidence that zolpidem keeps working safely for months or years.

5. Zolpidem with CBT-I

In a Canadian trial of 160 adults, CBT alone and CBT plus zolpidem 10 mg produced similar response rates after 6 weeks (60% vs 61%). Combined therapy gave a larger increase in sleep time. The best long-term outcome came from starting with the combination and then stopping zolpidem while continuing CBT. At 6-month follow-up, remission was 68% in that group compared with 42% in people who kept taking zolpidem (Morin et al., JAMA 2009). CBT-I on its own improved sleep latency by about 19 minutes and wake time after sleep onset by about 26 minutes in a meta-analysis of 20 trials, and the effects seemed to last (Trauer et al., Ann Intern Med 2015). This is similar to the benefit zolpidem shows over placebo, without the dependence risk. Our sleep prevention guide covers CBT-I techniques and sleep habits in detail.

6. What "clinically meaningful" means here

The AASM task force judged that most well-informed patients would choose zolpidem over no treatment, because of improvements in sleep latency, total sleep time, wake time, efficiency and quality and a "relatively low potential for adverse events". It still rated the evidence very low and the recommendation weak (AASM 2017). In 2023, the geriatrics panel reached the opposite judgement for people aged 65 and over, citing "minimal improvement in sleep latency and duration" alongside falls, fractures, delirium and crashes (Beers 2023). Both bodies read broadly the same evidence. The difference lies in whose risk they weigh most heavily.

Risks and all side effects

Boxed warning: complex sleep behaviours (FDA, 2019)

In April 2019 the FDA reported "rare but serious injuries" with eszopiclone, zaleplon and zolpidem caused by sleep behaviours including sleepwalking, sleep-driving and engaging in other activities while not fully awake. It said these "have also resulted in deaths" (FDA 2019). The Ambien label now carries a boxed warning: these behaviours may occur after the first or any later dose, and "some of these events may result in serious injuries, including death". Other reported behaviours include preparing and eating food, making phone calls and having sex, usually with no memory of the event. They can occur at recommended doses, with or without alcohol or other sedatives. Zolpidem must be stopped immediately if one happens, and it is contraindicated in anyone who has had such an episode (FDA label). The UK SmPC notes that alcohol, other sedatives and doses above the maximum appear to increase the risk (UK SmPC).

Next-morning impairment and driving

The FDA's January 2013 safety announcement was based on driving-simulation and laboratory studies. They showed that zolpidem blood levels above about 50 ng/mL "appear capable of impairing driving to a degree that increases the risk of a motor vehicle accident". About 8 hours after a 10 mg dose, about 15% of women and 3% of men exceeded that level. After extended-release 12.5 mg, about 33% of women and 25% of men did. The FDA warned that patients can be impaired "even if they feel fully awake" (FDA 2013).

Real-world data point the same way. In a Washington State cohort of 409,171 licensed drivers, new users of zolpidem had a higher crash risk than non-users (HR 2.20, 95% CI 1.64 to 2.95). The authors reported that the risk estimates across the three sedatives studied were equivalent to blood alcohol levels of 0.06% to 0.11% (Hansen et al., AJPH 2015). This is observational evidence, so people with insomnia may differ in other ways from people without it.

The dispute over sex differences is worth knowing about. A 2019 reanalysis confirmed that women clear zolpidem about 35% more slowly than men. It found that active drug was not distinguishable from placebo at 8 hours in laboratory studies, and that on-road driving studies showed no impairment at 8 hours after 10 mg in either sex. The authors argued the women's dose reduction "is not supported by available scientific evidence" and noted that no other regulator had copied it (Greenblatt et al. 2019). The FDA label still recommends 5 mg as the starting dose for women (FDA label). Both sides agree that the 8-hour window matters: the risk rises sharply if zolpidem is taken with less than a full night (7–8 hours) left, at higher doses, or with alcohol or other sedatives.

Dependence, tolerance and withdrawal

Both labels warn that zolpidem can cause physical and psychological dependence, and that the risk increases with dose and duration and is higher in people with a history of alcohol or drug misuse (FDA label; UK SmPC). Reported withdrawal symptoms include rebound insomnia, anxiety, tremor, sweating, agitation, confusion, headache, palpitations, nightmares, hallucinations and panic attacks. In severe cases they include hypersensitivity to light, noise and touch, and in very rare cases seizures. Symptoms can appear between doses with short-acting drugs (UK SmPC). In France, rising abuse and forged prescriptions led regulators to impose secure prescription pads in 2017. Reimbursed zolpidem use then fell by about 57%, but the share of dependence reports in people for whom zolpidem was the main substance rose from 43.6% to 59.3% (Aquizerate et al. 2023).

Falls, fractures and older adults

The evidence on falls and fractures is consistent across studies, but it is all observational:

  • A meta-analysis of 14 studies found Z-drugs associated with fractures (OR 1.63, 95% CI 1.42 to 1.87, with high heterogeneity) and zolpidem associated with injuries (OR 2.05, 95% CI 1.95 to 2.15). The increase in falls (OR 2.40) was not statistically significant (Treves et al., Age Ageing 2018).
  • In 15,528 US nursing home residents with hip fracture, Z-drug use was linked to a higher risk (OR 1.66), and the risk was highest in new users (OR 2.20) (Berry et al., JAMA Intern Med 2013).
  • In people with dementia in England, new Z-drug use was associated with more fractures (HR 1.40) and hip fractures (HR 1.59), with risk rising with cumulative dose. The mortality association (HR 1.34) was judged "unlikely to be causal" (Richardson et al., NIHR HTA 2021).
  • The FDA label reports that in non-US trials, 30 of 1,959 zolpidem patients had falls. Of these, 28 were aged 70 or over, and 23 of those 28 were taking doses above 10 mg (FDA label).

Mortality: an association, not a proof

A US matched cohort found that people prescribed any hypnotic, including zolpidem, had more than three times the hazard of death, even at fewer than 18 pills a year (Kripke et al., BMJ Open 2012). This study cannot prove cause and effect. People who are prescribed sleeping pills often have other health problems, and the lead author declared a long-standing public position against hypnotics. The UK dementia study also judged its mortality finding unlikely to be causal (Richardson et al. 2021). We grade the mortality signal Insufficient for causation.

Full side-effect table

Effect How often / severity What to do Source
Daytime sleepiness, next-day drowsiness Common (more than 1 in 100). In 28–35-night trials, drowsiness was 8% on zolpidem vs 5% on placebo. Do not drive, cycle or use machinery; avoid alcohol. NHS; FDA label
Bitter or metallic taste, dry mouth Common. Dry mouth was 3% vs 1% in longer trials. Sips of water; ask a pharmacist about a suitable mouthwash. NHS
Dizziness, "drugged" feeling, lethargy Common. Dizziness was 5% vs 1% and drugged feeling 3% vs 0% in 28–35-night trials. Sit or lie down; take care getting up at night. FDA label
Headache, nausea, vomiting, diarrhoea, back pain Common Speak to a pharmacist if persistent. NHS
Anterograde amnesia (no memory of events after dosing) Common in the UK SmPC; more often reported at doses above 10 mg Take only immediately before bed with 7–8 hours available. UK SmPC; FDA label
Complex sleep behaviours (sleepwalking, sleep-driving, cooking, phone calls, sex while not awake) Rare; serious injuries and deaths reported (boxed warning) Stop and contact a doctor; do not take again. FDA 2019
Hallucinations, delusions, abnormal behaviour, agitation, depersonalisation Hallucinations in under 1% of adults on 10 mg in trials; 7% of children in a paediatric trial Stop and call a doctor or 111. FDA label; NHS
Worsening depression, suicidal thoughts Reported with sedative-hypnotics; causal link not established Seek urgent help; prescribers should supply the smallest feasible quantity. UK SmPC; FDA label
Falls and fractures Consistent association, especially in people aged 65+, new users and people with dementia Discuss alternatives; take fall-prevention steps. Treves 2018; Berry 2013
Severe allergic reaction (angioedema, anaphylaxis) Rare; airway swelling can be fatal Call 999 / 911; never take zolpidem again. NHS; FDA label
Breathing suppression Very rare alone; higher risk with sleep apnoea, lung disease, myasthenia gravis or opioids Contraindicated in obstructive sleep apnoea in the UK. UK SmPC
Dependence, tolerance, withdrawal, rebound insomnia Risk rises with dose and duration, especially beyond 4 weeks Taper under supervision; do not stop suddenly after long use. UK SmPC; NHS
Hepatic encephalopathy in severe liver disease GABA-acting drugs can trigger it Do not use in severe liver impairment. FDA label
Overdose From drowsiness to coma, heart and breathing compromise; fatal outcomes reported, especially with other sedatives In the UK, contact 111 after any extra dose; call 999 if the person cannot be woken. NHS; FDA label

Suspected side effects can be reported through the MHRA Yellow Card scheme in the UK (NHS) or through FDA MedWatch in the US (FDA).

All interactions

Interacts with Examples Severity Mechanism Action
Alcohol Any alcoholic drink Avoid Adds to sedation and psychomotor impairment; can cause very deep sleep with poor breathing; raises the risk of complex sleep behaviours. Do not drink alcohol while taking zolpidem (NHS; UK SmPC).
Opioids Codeine, tramadol, morphine, oxycodone, methadone, pethidine, heroin High: sedation, respiratory depression, coma, death Additive depression of the central nervous system Only if there are no alternatives, at the lowest dose for the shortest time, with close monitoring (UK SmPC; FDA label).
Other sedatives and sleeping pills Benzodiazepines (diazepam, temazepam), other Z-drugs, other zolpidem products High Additive sedation and next-day impairment The FDA label advises against combining with other sedative-hypnotics at bedtime or in the middle of the night.
Sedating antihistamines Chlorphenamine, promethazine, and over-the-counter sleep aids containing diphenhydramine or doxylamine Moderate to high Additive sedation Check with a pharmacist first (NHS).
Antidepressants Sertraline, fluoxetine, bupropion, desipramine, venlafaxine, imipramine Moderate Sertraline raised zolpidem peak levels by 43%; isolated reports of visual hallucinations; imipramine adds to reduced alertness. The prescriber should review; watch for hallucinations or excess sedation (FDA label; UK SmPC).
Fluvoxamine Fluvoxamine Not recommended Inhibits CYP1A2 (strongly) and CYP3A4, which may raise zolpidem levels Concurrent use not recommended in the UK (UK SmPC).
Ciprofloxacin Ciprofloxacin (antibiotic) Not recommended Inhibits CYP1A2 and CYP3A4 Concurrent use not recommended in the UK (UK SmPC).
Strong CYP3A4 inhibitors Ketoconazole, itraconazole, ritonavir Moderate Ketoconazole increased total zolpidem exposure by about 1.7–1.8 times A lower zolpidem dose may be considered (FDA label; NHS).
CYP3A4 inducers Rifampicin, St John's wort Not recommended Rifampicin cut zolpidem exposure by 73%; St John's wort lowered peak and total levels by about a third Reduces the effect; avoid combining (UK SmPC). See our St John's wort review.
Antipsychotics, antiepileptics, anxiety medicines Chlorpromazine, quetiapine, gabapentinoids, pregabalin Moderate Additive sedation; chlorpromazine impaired alertness and psychomotor performance The prescriber should review doses (NHS). Beers advises against combining 3 or more CNS-active drugs in older adults.
Sedating herbal remedies and supplements Valerian and other "sleep" herbs Moderate Additive sedation; interactions are not well tested Do not take herbal remedies that make you sleepy (NHS). See our sleep supplements evidence review.
Cannabis and other recreational drugs Cannabis, heroin High Increased sedation; very deep sleep with difficulty waking Talk to a doctor (NHS).
Caffeine Coffee, tea, cola, energy drinks Reduces effect Opposing stimulant effect The NHS advises avoiding caffeine drinks while on zolpidem (NHS).
Food A meal before the dose Minor Peak levels fall by 25% and are delayed Slower sleep onset if taken with or just after a meal (FDA label).

Who should avoid zolpidem

  • Absolute contraindications (UK): allergy to zolpidem, obstructive sleep apnoea, myasthenia gravis, severe liver insufficiency, and acute or severe respiratory depression. It should not be prescribed to children or to people with psychotic illness (UK SmPC).
  • Anyone who has had a complex sleep behaviour on zolpidem, eszopiclone or zaleplon (FDA 2019).
  • People with a history of alcohol or drug misuse, or mental health problems: tell the doctor, because these raise dependence risk and the need for caution (NHS; UK SmPC).
  • People with depression: sedative-hypnotics can unmask or worsen depression, and intentional overdose is more common in this group (FDA label). If insomnia is part of depression or anxiety, see our stress, anxiety and depression guide.
  • Older adults (65+): the Beers Criteria say avoid, with a strong recommendation, and also avoid in delirium, dementia, or a history of falls or fractures (Beers 2023). Where it is still used, UK and US labels set 5 mg as the dose.
  • Liver disease: start at 5 mg for mild to moderate impairment; do not use in severe impairment. Kidney disease: the US label found no significant change in kinetics and no adjustment needed. The NHS notes a doctor may start at 5 mg in kidney problems (FDA label; NHS).
  • Pregnancy: not usually recommended. Use near the end of pregnancy can cause drowsiness, floppiness, feeding problems, breathing depression or withdrawal in the newborn. Published data have not shown a clear link with major birth defects (NHS; FDA label).
  • Breastfeeding: passes into milk in very small amounts. The NHS says occasional short-term doses may be acceptable if the baby is healthy. Do not share a bed with your baby while taking it (NHS).
  • People who must be fully alert early the next morning (for example, professional drivers or shift workers): the FDA says extended-release zolpidem "may not be the right medication choice" for anyone who needs to drive the next morning (FDA 2013).

Dosage and how to take it

Your prescriber sets the dose. The ranges below are the official licensed ranges for adults, given for information only.

Setting Licensed adult dose Maximum / duration Source
UK (NHS / SmPC), adults 10 mg immediately at bedtime, taken once Do not exceed 10 mg. Usually 2 days to 4 weeks; no more than 4 weeks including tapering. The doctor may prescribe it for only 2–3 nights a week. NHS; UK SmPC
UK, 65+ or kidney/liver problems 5 mg 10 mg only for under-65s with liver impairment if response is inadequate and it is well tolerated UK SmPC
US, Ambien (immediate-release) Women: 5 mg. Men: 5 or 10 mg. Taken once, immediately before bed, with at least 7–8 hours before waking. No more than 10 mg a night; do not repeat the same night; "as short as possible" FDA label
US, Ambien CR (extended-release) Women: 6.25 mg. Men: 6.25 or 12.5 mg. Swallow whole; do not crush, split or chew. No more than 12.5 mg a night FDA Ambien CR label
US, older adults and mild to moderate liver impairment 5 mg (immediate-release) or 6.25 mg (extended-release) Avoid in severe liver impairment FDA label

How long it takes to work: around 30 minutes (NHS). Take it in bed or just before bed, never earlier in the evening. The US label says to re-evaluate if insomnia continues after 7–10 days, and the UK SmPC says after a 7–14-day course, because persistent insomnia can signal another medical or psychiatric problem (FDA label; UK SmPC).

Missed dose: skip it; never take two doses together or take a second dose in the same night (NHS).

How to stop: the UK product information asks prescribers to agree a plan for ending treatment before starting, to reduce the risk of dependence (UK SmPC). If zolpidem has been taken for less than 4 weeks, stopping is unlikely to cause problems. After longer use, do not stop suddenly. A doctor may reduce the dose gradually over days or weeks to prevent withdrawal and rebound insomnia (NHS). Starting CBT-I while tapering is supported by trial evidence (Morin et al. 2009).

Follow the money: who makes it and who funded the evidence

Who made it and who sells it

  • Originator: Synthélabo (France), which launched zolpidem in France in 1988 (Inpharma 1988). Synthélabo merged with Sanofi in 1999 to form Sanofi-Synthélabo, which combined with Aventis in 2004. Today's company, Sanofi, is registered at 46 avenue de la Grande Armée, Paris (Sanofi 20-F 2012; SEC EDGAR, Sanofi 20-F 2025).
  • Revenue: Sanofi reported Stilnox/Ambien/Myslee sales of €822 million (2008), €873 million (2009) and €819 million (2010). In 2010, €375 million of this came from Ambien CR in the US. After US generics of Ambien CR arrived in October 2010, sales fell to €490 million (2011) and €497 million (2012). By then Japan (Myslee, co-promoted with Astellas) was a major market (Sanofi 20-F 2010; Sanofi 20-F 2012).
  • US brand today: on 10 July 2024, Cosette Pharmaceuticals (Bridgewater, New Jersey; backed by the private equity firm Avista Capital Partners) completed its purchase of the US rights to Ambien and Ambien CR from Sanofi US. It cited IQVIA figures of US$39 million in US sales for the 12 months to April 2024 (Cosette press release). Drugs@FDA now lists Cosette as the sponsor of NDA 019908 (Drugs@FDA), although a Sanofi-Aventis U.S. label was still listed on DailyMed when we checked (DailyMed).
  • Generics: zolpidem is off-patent almost everywhere. openFDA lists 12 US generic (ANDA) applications. In the UK, generic licences include Zentiva Pharma UK (licensed 2002) and Novumgen (orodispersible Zalzo, 2024) (UK SmPC). Because the product is cheap and generic, no company today has a large commercial stake in promoting it. Most of the money was made between 1992 and 2010.

Who funded the evidence

  • The approval trials were run by the manufacturer. The label's efficacy studies lasted 4–5 weeks in total (FDA label). The AASM guideline downgraded its evidence for zolpidem and other hypnotics partly because "very few clinical trials with adequate sample size have been sponsored by agencies outside of industry", which creates a risk of publication bias (AASM 2017).
  • The independent reanalyses are the most useful checks. The BMJ 2012 analysis had no funding and no conflicts, and it used FDA-held data, including results that may never have been published (BMJ 2012). The Lancet 2022 network meta-analysis was paid for with UK public money. Its declared author ties are to other companies (Boehringer Ingelheim, Angelini, Janssen), not to zolpidem's makers (Lancet 2022).
  • The safety research is mostly public. Funders include the US National Institute on Aging (Berry 2013), the UK NIHR (Richardson 2021) and French academic addictovigilance centres (Aquizerate 2023). The key CBT-I comparison trial was funded by the US National Institute of Mental Health, although its lead author had consulted for Sanofi-Aventis (Morin 2009).
  • Allegiance can run both ways. The strongest mortality claims come from an author who publicly campaigns against hypnotics (Kripke 2012). The strongest challenge to the FDA's women's-dose rule comes from long-standing pharmacology researchers (Greenblatt 2019). We could not check their funding from the abstract. Neither position should be accepted or dismissed because of who holds it.
  • Regulators changed course against commercial interest. The FDA's 2013 dose cut and 2019 boxed warning were both safety actions that could only reduce sales. They are therefore unlikely to have been shaped by the manufacturers' interests, even though industry user fees fund much of FDA drug review (FDA PDUFA report FY2025).

We found no documented research-misconduct finding specific to zolpidem trials in the sources we reviewed.

Frequently asked questions

How long does zolpidem take to work?

Around 30 minutes, so it should be taken just before bed (NHS). Taking it with or straight after a meal can delay the effect (FDA label).

Can you drink alcohol on zolpidem?

No. Alcohol and zolpidem together can make you sleep so deeply that you do not breathe properly and are hard to wake (NHS). Alcohol also increases the risk of sleep-driving and other complex sleep behaviours (UK SmPC).

Is zolpidem addictive?

It can cause dependence, and the risk rises with dose and duration. The NHS says you are unlikely to become addicted if you take it for up to 4 weeks, but may become dependent if you take it for longer (NHS). In the US it is a Schedule IV controlled substance (FDA label).

How do I stop zolpidem safely?

After less than 4 weeks, stopping usually causes no problems. After longer use, do not stop suddenly. Ask your doctor to plan a gradual reduction over days or weeks to avoid withdrawal symptoms and rebound insomnia (NHS). CBT-I during and after the taper gave the best long-term results in a randomised trial (Morin et al. 2009).

Can I drive the morning after taking zolpidem?

Only if you have had a full 7–8 hours in bed, took the prescribed dose, have had no alcohol or other sedatives, and do not feel drowsy, dizzy or blurry. Even then, the FDA warns that impairment can be present when you feel fully awake (FDA 2013). In the UK it is an offence to drive if your ability is impaired (NHS).

Why do women get a lower dose of Ambien in the US?

In 2013 the FDA found that women clear zolpidem more slowly. About 15% of women, compared with 3% of men, had potentially driving-impairing blood levels 8 hours after 10 mg. It therefore set 5 mg as the starting dose for women (FDA 2013). The UK licence did not adopt this split. One academic reanalysis argues the evidence does not support it (Greenblatt et al. 2019).

Does zolpidem cause weight gain or memory loss?

Weight gain is not listed among its common side effects (NHS). Memory gaps for the period after a dose (anterograde amnesia) are a recognised common effect, especially at doses above 10 mg or if you stay up after taking it (UK SmPC; FDA label). Tell your doctor about any new memory loss (NHS).

Is zolpidem safer than benzodiazepines like temazepam?

Not clearly. NICE found no compelling evidence to separate zolpidem, zopiclone and short-acting benzodiazepines (NICE TA77). The Beers Criteria say Z-drugs have adverse events similar to benzodiazepines in older adults (Beers 2023).

Sources and funding notes

Last reviewed: 26 September 2026. Educational information from Pure City Research, not medical advice. Medicine decisions belong with a qualified prescriber.

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