Zopiclone Side Effects

Zopiclone can help with severe short-term insomnia, but it can also affect taste, alertness, balance, memory, breathing and behaviour. The most common zopiclone side effects are a bitter or metallic taste, dry mouth and feeling sleepy, dazed or less alert the next day. Not everyone experiences them, and their severity varies.

This UK guide explains which reactions are common, which warning signs need urgent help, how zopiclone can affect cognitive function, and why repeated or long-term use requires a prescriber’s review. It is general information, not a diagnosis or a personal dosing plan.

Answer: What Side Effects Can Zopiclone Cause?

The NHS identifies bitter or metallic taste, dry mouth and next-day tiredness or reduced alertness as common reactions. Other reported effects include dizziness, headache, nausea, vomiting, nightmares, agitation, confusion, hallucinations, memory impairment and disturbed attention.

Rare but serious problems can include a severe allergic reaction, breathing difficulty, profound sedation and complex sleep behaviours such as sleepwalking or doing activities while not fully awake. Alcohol, opioids and other sedating medicines can increase danger.

What Is Zopiclone and Why Can It Cause Side Effects?

Zopiclone is a prescription-only sleeping medicine used for short-term treatment of severe insomnia in adults. It is often called a Z-drug. It enhances the effect of gamma-aminobutyric acid, or GABA, a chemical messenger that reduces activity in the brain.

That calming action can help a person fall asleep or wake less often. The same action can also slow reactions, reduce coordination, affect memory and make breathing suppression more likely when combined with other central nervous system depressants.

A reaction can be influenced by dose, age, liver or breathing problems, other medicines, alcohol, the amount of uninterrupted sleep available and individual sensitivity. A lower strength does not guarantee that a person will avoid unwanted effects.

Common Side Effects of Zopiclone

UK product information classifies bitter taste and residual sleepiness as common nervous-system effects and dry mouth as a common gastrointestinal effect. “Common” is a frequency category; it does not mean every user will experience the reaction.

Bitter or Metallic Taste

A bitter or metallic taste is one of the best-known reactions. It may begin after the tablet or remain the following morning. Water, sugar-free gum or sugar-free sweets may make it easier to manage. Persistent taste disturbance should be discussed with a pharmacist, particularly if it affects eating or hydration.

Dry Mouth

Dry mouth may feel uncomfortable during the night or on waking. Regular sips of water and sugar-free gum can help. A pharmacist can suggest a suitable dry-mouth product. Ongoing dry mouth matters because reduced saliva can contribute to dental problems.

Next-Day Sleepiness and Reduced Alertness

Some people wake feeling tired, heavy-headed, dazed or slower than usual. This can affect concentration, work, study, balance and driving even if the person believes they slept through the night.

The NHS advises not to drive, cycle or use machinery for 12 hours after taking zopiclone. The UK product information also warns that impairment is more likely when the medicine is taken within 12 hours of an activity requiring alertness, when more than the recommended dose is taken, or when it is combined with alcohol or another central nervous system depressant.

Do not judge fitness to drive only by the clock. If sleepiness, dizziness, slowed thinking or poor coordination remains, do not drive or perform hazardous tasks.

Dizziness and Headache

Dizziness and headache are listed as uncommon in current UK product information. If dizzy, sit or lie down, stand slowly and avoid stairs or activities where a fall could cause harm. Persistent or severe symptoms need professional advice. The site’s dedicated guide on sleeping pills and dizziness explains practical fall-safety steps.

Nausea, Vomiting and Digestive Discomfort

Nausea and vomiting can occur. Small sips of water may help with hydration, but repeated vomiting, severe weakness or inability to keep fluids down should be assessed. Do not take an additional tablet because vomiting occurred unless a prescriber specifically advises it.

Nightmares, Agitation and Mood Changes

Nightmares and agitation are recognised uncommon reactions. Rare reports include irritability, aggression, confusion and hallucinations. A new, marked change in behaviour or mood should not be dismissed as ordinary tiredness. Contact the prescriber promptly, and obtain urgent help if someone is unsafe.

Serious Side Effects and When to Get Help

Serious reactions are less common, but recognising them is important.

Call 999 for severe breathing difficulty, blue or grey lips, collapse, a seizure, loss of consciousness, an inability to wake normally, or signs of a severe allergic reaction such as swelling of the lips, mouth, tongue or throat with breathing difficulty.

Contact NHS 111 or seek urgent clinical advice for hallucinations, marked confusion, unusual aggression, severe unsteadiness, a suspected medicine interaction, or complex sleep behaviour. Anyone with thoughts of self-harm or immediate danger needs urgent help; call 999 in an emergency.

Complex Sleep Behaviours

Sleepwalking, preparing or eating food, making calls, having sex or attempting to drive while not fully awake have been reported. The person may have little or no memory of the event. Current product information advises immediate discontinuation if complex sleep behaviour occurs, but because stopping plans depend on duration and pattern of use, contact the prescriber urgently for individual instructions rather than managing the situation alone.

Breathing Problems

Zopiclone can depress breathing, particularly in people with compromised respiratory function or when taken with opioids, alcohol or other sedatives. Loud snoring, witnessed pauses in breathing, choking during sleep or pronounced daytime sleepiness may suggest sleep apnoea and should be discussed before or during treatment.

Combining zopiclone with opioids can result in profound sedation, respiratory depression, coma and death. A prescriber must review any proposed combination and monitor it closely.

Severe Allergic Reaction

Angioedema and anaphylactic reactions are listed as very rare. Facial, tongue or throat swelling, wheezing, difficulty swallowing or breathing, or sudden collapse requires emergency help.

How Does Zopiclone Use Affect Cognitive Function?

“Cognitive function” means mental skills such as attention, memory, reaction speed, judgement and the ability to process information. Zopiclone’s sedating action can temporarily reduce these abilities, especially during the night and the following morning.

Current UK product information lists memory impairment, disturbance in attention and speech disorder among effects whose frequency cannot be estimated from available data. It also lists rare anterograde amnesia—difficulty forming new memories after taking the medicine.

Memory

Memory risk is greater if sleep is interrupted or the tablet is taken without enough time for a full night’s sleep. A person may speak, eat or perform another activity and later remember little about it. Taking the medicine only when ready for bed and allowing about seven to eight hours of uninterrupted sleep reduces, but does not remove, this risk.

Attention and Reaction Time

Residual sedation can make attention less steady and reactions slower. A person may feel “awake” but still perform less safely. This matters for driving, operating machinery, working at height, cooking with heat, caring for another person or making important decisions.

Confusion and Judgement

Confusion is uncommon or rare in product information but can be more consequential in older or frail adults. Sedation and poor balance can also increase fall risk. Sudden confusion needs prompt assessment because medicines are only one possible cause.

Does Long-Term Zopiclone Cause Permanent Cognitive Decline?

It would be inaccurate to promise that long-term zopiclone causes—or does not cause—permanent cognitive decline in every user. Observational research on hypnotics can be affected by age, insomnia severity, other illnesses and concurrent medicines. Stronger and more direct evidence supports short-term impairment of alertness, attention, memory and psychomotor performance.

The practical message is clearer than the unresolved research question: persistent forgetfulness, reduced attention, daytime slowing or falls while using zopiclone deserve a medication review. Do not increase the dose to overcome tolerance, and do not stop regular treatment suddenly.

Long-Term Risks of Zopiclone

Zopiclone is normally intended for short courses. NHS guidance says it is usually prescribed for two to four weeks because the body can quickly become used to it and dependence can develop.

Tolerance

Tolerance means the same dose feels less effective over time. Wanting a higher dose, taking extra tablets or adding another sedative are warning signs—not reasons to self-adjust treatment. The January 2026 MHRA update strengthened UK warnings about tolerance, dependence, addiction and withdrawal for Z-drugs.

If treatment appears less effective, use the site’s guide to zopiclone not working to prepare questions for a prescriber rather than taking more.

Physical Dependence

Physical dependence is a body adaptation to repeated use. It is not the same as addiction, although the two can overlap. Dependence can occur with therapeutic use and may cause withdrawal when the dose is reduced or stopped abruptly.

Risk generally rises with longer duration and higher doses, but the MHRA notes that dependence and addiction can also occur during short-term use at recommended doses. Previous substance-use problems and some mental health conditions may increase risk and warrant closer monitoring.

Addiction or Problematic Use

Possible signs include craving, difficulty controlling use, taking the medicine for reasons other than prescribed, seeking early refills, using someone else’s tablets or continuing despite harm. These signs should be discussed without blame. The dedicated zopiclone dependence and addiction guide covers this topic in more depth.

Withdrawal and Rebound Insomnia

Abrupt discontinuation after regular use can cause withdrawal. Symptoms may include worse sleep, anxiety, agitation, sweating, tremor, headache, confusion or heightened sensitivity to sound and light. Severe reactions can occur.

Rebound insomnia means the original sleep problem temporarily returns more strongly. It can make a person believe the medicine is permanently necessary, even when the symptoms are part of withdrawal.

The MHRA advises an individual, gradual reduction strategy when treatment ends. A high-dose taper may take weeks or months. The site’s zopiclone withdrawal guide can support a conversation, but only a clinician who knows the person’s history should set the schedule.

Falls, Accidents and Daytime Function

Ongoing sedation, dizziness, poor coordination and reduced attention can contribute to falls, work errors and road risk. Older adults, people who get up during the night and those taking several sedating medicines may be particularly vulnerable.

Mood and Behaviour

New depression, emotional changes, anxiety, irritability, hallucinations or unusual behaviour require review. Insomnia itself can affect mood, so a clinician should consider the whole picture rather than assuming one cause.

Factors That Can Increase the Risk

Alcohol and Medicine Interactions

Do not drink alcohol with zopiclone. The combination can cause very deep sleep, poor coordination, difficulty waking and breathing problems. Read the detailed zopiclone and alcohol safety guide for the specific risks.

Tell the prescriber and pharmacist about prescription medicines, over-the-counter products, herbal products and medicines obtained online. Opioid painkillers, benzodiazepines, sedating antihistamines, antipsychotics, some antidepressants, epilepsy medicines and other sleep medicines may alter sedation or zopiclone levels.

Do not borrow another person’s medicine or combine sleep products to “make them work.” If a possible interaction has already occurred and the person is difficult to wake, breathing unusually or severely confused, call 999.

How to Use Zopiclone Safely

No medicine use is risk-free, but the following actions reduce avoidable harm:

1. Use zopiclone only when prescribed for you and follow the labelled dose.
2. Take it as directed when ready to go to bed, with enough time for a full night’s sleep.
3. Never take a second dose during the same night unless a prescriber has explicitly instructed it.
4. Avoid alcohol and recreational drugs.
5. Do not combine it with opioids or other sedatives without a clinician’s approval.
6. Do not drive, cycle, use machinery or perform hazardous work for at least 12 hours after a dose, and longer if affected.
7. Keep the medicine secure and never share it.
8. Arrange a review if treatment continues, feels less effective or affects daytime function.
9. Agree an ending or reduction plan with the prescriber; do not improvise a taper.
10. Read the patient information leaflet supplied with the exact product because formulations and warnings can differ.

Zopiclone treats symptoms for a short period; it does not address every cause of insomnia. For ongoing sleep difficulty, discuss CBT-I and the broader pathway in the UK insomnia treatment guide.

What to Do If a Side Effect Occurs

For a mild bitter taste or dry mouth, try the simple measures above and ask a pharmacist if the problem persists. For next-day sleepiness or dizziness, stop driving and other risky activity until fully alert.

Contact a doctor, pharmacist or NHS 111 when a reaction is persistent, worsening, interfering with daily life, or accompanied by confusion, memory problems, mood change or unusual behaviour. Ask for a medication review if the medicine is being used regularly or no longer works as before.

Call 999 for severe breathing difficulty, collapse, seizure, inability to wake, a serious allergic reaction or immediate danger. If overdose is suspected, do not wait for symptoms and do not make the person vomit; obtain emergency advice.

Frequently Asked Questions

What are the most common zopiclone side effects?

Bitter or metallic taste, dry mouth and feeling sleepy, tired, dazed or less alert the next day are the common reactions highlighted by the NHS.

How long do side effects last?

Duration varies with the reaction, dose, timing, other substances and the individual. Residual sedation may continue into the next day. Persistent, severe or worsening symptoms need professional advice.

Can zopiclone affect memory?

Yes. Rare anterograde amnesia and other cognitive effects, including memory impairment and disturbed attention, are described in UK product information. Interrupted sleep and insufficient sleep time can increase risk.

Can zopiclone affect concentration the next day?

Yes. Residual sleepiness and psychomotor impairment can reduce concentration, coordination and reaction speed. Avoid driving and hazardous tasks while affected.

Can zopiclone cause sleepwalking?

Complex sleep behaviour, including sleepwalking and performing activities while not fully awake, has been reported. Contact the prescriber urgently if this occurs.

Does zopiclone cause dementia?

Available evidence does not prove that zopiclone directly causes dementia in every user. There is clearer evidence of short-term impairment in memory, attention and alertness. Persistent cognitive symptoms require clinical review.

What are the main long-term risks?

Tolerance, physical dependence, addiction, withdrawal, rebound insomnia and ongoing daytime impairment are important concerns. Regular use should be reviewed rather than continued automatically.

Can I stop zopiclone if side effects occur?

Urgent reactions need prompt medical help. If zopiclone has been taken regularly, do not stop abruptly without advice because withdrawal may occur. Ask the prescriber for an individual plan.

Can I drink alcohol while taking zopiclone?

No. Alcohol can greatly increase sedation, impaired coordination, breathing problems and difficulty waking.

When should I call 999?

Call 999 for severe breathing difficulty, blue or grey lips, collapse, seizure, inability to wake normally, severe allergic reaction or immediate risk of serious harm.

Conclusion

The main zopiclone side effects are bitter or metallic taste, dry mouth and next-day tiredness or reduced alertness. Dizziness, nausea, headache, nightmares and agitation can also occur. Memory impairment, disturbed attention, confusion, hallucinations, complex sleep behaviour, respiratory depression and severe allergy require greater caution.

Long-term or repeated use adds the risks of tolerance, dependence and withdrawal. Use zopiclone only as prescribed, avoid alcohol and unsafe sedative combinations, allow enough sleep time, and never drive while impaired. Persistent symptoms, cognitive changes or difficulty stopping deserve a professional medication review.

Zopiclone is a prescription-only medicine intended mainly for short-term treatment of severe insomnia.

This guide is general information and does not replace advice from your prescriber or pharmacist.

Do not combine zopiclone with alcohol, opioids or other sedatives unless a clinician has reviewed the combination.

Do not increase the dose or stop regular treatment suddenly; ask for an individual reduction plan.

Call 999 for severe breathing difficulty, collapse, seizure, inability to wake or a severe allergic reaction.