From the Guidelines
Zopiclone can cause several side effects, including bitter or metallic taste, drowsiness, dizziness, headache, and dry mouth, and more concerning effects like memory problems, confusion, and dependence, as reported in a systematic review 1.
Common Side Effects
- Bitter or metallic taste in the mouth
- Drowsiness that may persist into the following day
- Dizziness
- Headache
- Dry mouth Some people may experience gastrointestinal issues like nausea or vomiting.
Concerning Side Effects
- Memory problems
- Confusion
- Hallucinations
- Changes in behavior
- Allergic reactions
- Dependence and withdrawal symptoms if stopped suddenly after regular use
Important Considerations
The medication typically comes in 3.75mg or 7.5mg tablets (or 1mg, 2mg, or 3mg for eszopiclone), with elderly patients usually prescribed lower doses. Patients should avoid alcohol while taking zopiclone as this can dangerously increase sedation.
Administration and Monitoring
To minimize the incidence of adverse events, a nonbenzodiazepine BZRA, if prescribed, should be administered at the lowest effective dose and for the shortest possible duration, and all patients offered these agents should be counseled on the potential risks 1. The U.S. Food and Drug Administration recently released a safety announcement on the risk for serious injuries caused by sleep behaviors (sleepwalking, sleep driving, and other activities while not fully awake) associated with these agents 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Side Effects of Zopiclone
The side effects of zopiclone, also known as eszopiclone, have been studied in various clinical trials and research studies. Some of the common side effects reported include:
- Bitter taste and dry mouth, as reported in a study published in 1993 2
- Minimal impairment to psychomotor performance and mental alertness the morning after night-time administration, as observed in a study published in 1993 2
- Rebound insomnia, although rare, as mentioned in a study published in 1997 3
- Dependence and abuse potential, which is considered rare, as concluded in a study published in 1997 3
- Effects on cognitive function, including verbal memory, attention, and working memory, as reported in a meta-analysis published in 2014 4
Cognitive Effects
The cognitive effects of zopiclone have been evaluated in several studies. A meta-analysis published in 2014 found that zopiclone had a medium effect size on measures of verbal memory and working memory 4. Another study published in 2019 found that withdrawal from long-term use of zopiclone may improve perceived sleep and quality of life in older adults with primary insomnia 5.
Withdrawal Effects
The effects of withdrawing from zopiclone have also been studied. A study published in 1998 found that substituting zopiclone in withdrawal from chronic use of benzodiazepine hypnotics may help reduce sleep disturbances and improve sleep quality 6. Another study published in 2019 found that withdrawal from long-term use of zopiclone may improve perceived sleep and quality of life in older adults with primary insomnia, with significant improvements in sleep-onset latency, difficulty in initiating sleep, and daytime fatigue 5.