Eszopiclone, sold under the brand-name Lunesta among others, is a medication used in the treatment of insomnia. Evidence supports slight to moderate benefit up to six months. It is taken orally.Common side effects include headache, dry mouth, nausea, and dizziness. Severe side effects may include suicidal thoughts, unhealthy non-medical use, hallucinations, and angioedema. Greater care is recommended in those with liver problems and older people. Rapid decreasing of the dose may result in withdrawal. Eszopiclone is classified as a nonbenzodiazepine sedative hypnotic and as a cyclopyrrolone. It is the S-stereoisomer of zopiclone. It works by interacting with the GABA receptors.Approved for medical use in the United States in 2004, eszopiclone is available as generic medication. In 2017, it was the 214th most commonly prescribed medication in the United States, with more than two million prescriptions.