Zopiclone is one of the most widely used sleep medications in the UK — and for good reason. It works quickly, effectively, and is well-tolerated by the majority of people who take it. But like any medication, it does come with a side effect profile that every user should understand before they start taking it.

This complete guide covers everything you need to know: common side effects, rare but serious reactions, how to minimise unwanted effects, what's safe for different groups of people, and when to seek medical advice.

How Zopiclone Works (And Why Side Effects Occur)

Zopiclone belongs to a class of drugs called non-benzodiazepine sedative-hypnotics (Z-drugs). It works by binding to GABA-A receptors in the brain — enhancing the calming effects of GABA, your brain's primary inhibitory neurotransmitter. This slows down neural activity, producing the drowsiness and sedation needed for sleep.

The reason side effects occur is that GABA receptors are found throughout the brain and central nervous system — not just in the regions that control sleep. When zopiclone enhances GABA activity system-wide, it can affect memory, muscle tone, mood, and other functions beyond just sleep induction. The dose you take directly influences how pronounced these effects are.

Common Side Effects of Zopiclone

These side effects affect a significant proportion of users — some estimates suggest they occur in 1 in 10 or more people taking zopiclone. They are generally mild, manageable, and tend to diminish as your body adjusts to the medication.

Uncommon Side Effects of Zopiclone

These side effects are less frequent — affecting roughly 1 in 100 to 1 in 1,000 users — but are worth knowing about. If you experience any of these, make a note and mention them to your doctor at your next appointment.

• Impaired coordination or balance — feeling unsteady on your feet, particularly at night if you get up to use the bathroom (fall risk, especially in elderly users)
• Memory problems (anterograde amnesia) — difficulty forming new memories for a short period after taking the medication, particularly if sleep is disrupted
• Mood changes — feeling low, anxious, or irritable the following day
• Confusion or disorientation — particularly in older patients or at higher doses
• Blurred vision — temporary visual disturbance upon waking
• Stomach upset or indigestion — gastrointestinal discomfort not explained by food intake
• Reduced libido — decreased interest in sexual activity with prolonged use
• Tremors — mild shaking, more commonly associated with higher doses

Serious Side Effects — When to Seek Medical Help Immediately

While rare, some side effects of zopiclone are serious and require prompt medical attention. Stop taking zopiclone and seek immediate help if you experience any of the following:

These reactions are uncommon, but they are serious. Zopiclone should never be combined with alcohol, opioids, or other central nervous system depressants, as this dramatically increases the risk of respiratory depression — a potentially life-threatening condition.

The Bitter Taste: Why It Happens & How to Manage It

The bitter or metallic taste is by far the most commonly reported side effect of zopiclone — and for many users, the most annoying. It typically appears in the mouth upon waking and can linger for several hours into the day.

Why Does It Happen?

Zopiclone is partially excreted through saliva as it is metabolised overnight. The drug itself has a naturally bitter taste, and as trace amounts pass into the saliva glands, this bitterness becomes noticeable — particularly in the morning when saliva flow increases.

How to Reduce the Bitter Taste:

• Brush your teeth immediately upon waking with a strong mint toothpaste
• Drink a glass of cold water or fruit juice first thing in the morning
• Chew sugar-free mint gum after waking
• Eat a light breakfast — food helps neutralise the taste
• Switch to eszopiclone — the refined isomer of zopiclone produces a noticeably milder bitter taste in most users (see section below)

Next-Day Grogginess: Causes & Solutions

Next-day drowsiness — sometimes called a "sleep hangover" — is a common complaint among zopiclone users, particularly those taking higher doses or those who didn't get a full 7–8 hours of sleep after taking the tablet.

Why Does It Happen?

Zopiclone has a half-life of approximately 5 hours — meaning half the drug is still active in your system 5 hours after taking it. If you take zopiclone at midnight and wake at 6am, there may still be a meaningful amount of the drug in your bloodstream, causing residual sedation.

How to Minimise Next-Day Drowsiness:

• Only take zopiclone when you have 7–8 hours to sleep — this is the single most important rule
• Take it at least 8 hours before you need to drive or operate machinery
• Start at the lowest effective dose — higher doses mean more residual sedation
• Avoid alcohol entirely — it dramatically extends sedation
• Stay well hydrated — dehydration worsens grogginess
• Consider switching to eszopiclone, which has a slightly longer but cleaner half-life with less next-day impairment reported in clinical studies

Dependence, Tolerance & Withdrawal

One of the most important considerations with zopiclone — particularly for longer-term users — is the potential for physical and psychological dependence.

Tolerance

With regular nightly use, your body can begin to adapt to zopiclone's effects — meaning the same dose produces a weaker response over time. This is called tolerance. It typically begins to develop after 2–4 weeks of continuous use. Signs of tolerance include:

• Taking longer to fall asleep than when you first started
• Waking more frequently during the night
• Feeling that the medication "isn't working anymore"

Dependence

Physical dependence occurs when your body becomes accustomed to the presence of the drug and struggles to function normally without it. This is more likely with daily use over several weeks. Signs of dependence include:

• Feeling anxious or unable to sleep without the medication
• Strong urge to take the tablet even when not needed
• Discomfort or insomnia when you try to stop

Withdrawal

Stopping zopiclone abruptly after prolonged use can cause rebound insomnia — a temporary worsening of sleep that is often worse than the original problem. Other withdrawal symptoms can include anxiety, irritability, tremors, and sweating.

Never stop zopiclone suddenly after extended use. Always taper the dose gradually under medical guidance. A typical tapering schedule reduces the dose by small amounts every 1–2 weeks until the medication is fully discontinued.

Side Effects in Special Patient Groups

Elderly Patients (65+)

Older adults are at significantly higher risk of zopiclone side effects. The liver and kidneys metabolise medication more slowly with age, meaning zopiclone stays in the system longer. This increases the risk of:

• Prolonged next-day sedation
• Falls and fractures due to dizziness or impaired balance
• Confusion and cognitive impairment

Recommendation: Elderly patients should always start at 3.75mg zopiclone or — ideally — eszopiclone 1mg, which is specifically designed as the lowest effective therapeutic dose.

People with Liver Impairment

The liver is responsible for breaking down zopiclone. Impaired liver function slows this process, causing the drug to accumulate and side effects to intensify. A reduced starting dose (3.75mg or eszopiclone 1mg) is essential in this group.

People with Respiratory Conditions

Zopiclone can suppress respiratory drive — the automatic urge to breathe. People with conditions such as COPD, sleep apnoea, or asthma should use zopiclone with extreme caution or avoid it altogether. Eszopiclone at the lowest dose may be a more suitable option, but only under medical supervision.

Pregnant or Breastfeeding Women

Zopiclone crosses the placenta and passes into breast milk. It should be avoided during pregnancy and breastfeeding except in exceptional circumstances under direct medical supervision.

How to Minimise Zopiclone Side Effects: 8 Practical Tips

1. Start at the lowest effective dose — 7.5mg for most adults, 3.75mg for elderly or sensitive individuals
2. Only take it when you have 7–8 hours to sleep — this single rule eliminates most next-day grogginess
3. Take it on an empty stomach or with only a light snack — a heavy meal delays absorption and can disrupt the medication's timing
4. Avoid alcohol completely — combining alcohol and zopiclone dramatically amplifies sedation and respiratory risk
5. Don't take other sedative medications alongside it — antihistamines, opioids, benzodiazepines, and some antidepressants all interact with zopiclone
6. Use it for short courses only — limit continuous use to 2–4 weeks to reduce dependence risk
7. Take medication breaks — try using zopiclone on alternate nights rather than every night to slow tolerance development
8. Keep your bedroom environment optimal — medication works best alongside good sleep hygiene: dark, cool, quiet room; consistent bedtime

Fewer Side Effects? Consider Eszopiclone

If you're troubled by zopiclone's side effects — particularly the bitter taste or next-day drowsiness — it's worth considering eszopiclone, the refined active isomer of zopiclone.

Because eszopiclone contains only the therapeutically active component of zopiclone (without the inactive isomer), it tends to produce:

• A milder bitter taste — significantly less pronounced than standard zopiclone
• Less next-day sedation — cleaner half-life profile
• Lower dependence risk — supported by longer-term clinical studies
• Equivalent or better sleep quality at a lower milligram dose

Eszopiclone is available in 1mg, 2mg, 3mg, and 6mg strengths. Browse our full eszopiclone range:

• Hypnite 1mg — lowest dose, ideal for elderly or sensitive users
• Hypnite 2mg — balanced mid-range eszopiclone dose
• Zunestar 2mg — eszopiclone USP 2mg
• Hypnite 3mg — full adult dose eszopiclone
• Zunestar 3mg — eszopiclone USP 3mg
• Eszopinap 3mg — eszopiclone 3mg tablets
• Zopfresh-E 6mg — high-strength eszopiclone

Frequently Asked Questions

How long do zopiclone side effects last?

Most common side effects — including the bitter taste and mild drowsiness — resolve within a few hours of waking. For first-time users, side effects may be slightly more noticeable in the first 2–3 nights and typically diminish as the body adjusts.

Does zopiclone cause weight gain?

Weight gain is not a commonly reported side effect of zopiclone. However, any medication that disrupts sleep architecture or daytime energy levels can indirectly affect appetite and activity levels over time.

Can zopiclone affect my memory?

Zopiclone can cause anterograde amnesia — difficulty forming new memories — particularly if you wake up during the night while the drug is still fully active. This is why you should always take zopiclone only when you intend to sleep for a full 7–8 hours.

Is it safe to take zopiclone with antidepressants?

Some antidepressants interact with zopiclone, particularly those with sedative properties. Always inform your doctor or pharmacist of all medications you are taking before starting zopiclone.

Can zopiclone cause depression?

Zopiclone can occasionally cause low mood or worsen existing depression in some users, particularly with prolonged use. If you notice a significant change in your mood while taking zopiclone, speak to your doctor promptly.

What happens if I take too much zopiclone?

Taking more than the recommended dose significantly increases the risk of serious side effects including severe respiratory depression. If you suspect an overdose, seek emergency medical help immediately by calling 999 or going to your nearest A&E.