These effects are rare and probably enhanced by alcohol. Because they cross the placenta and enter breast milk, pregnant women or nursing mothers should not routinely use these drugs. An association was reported between the use of benzodiazepines in the first trimester of pregnancy and the development of cleft lip in newborns. Overdoses are rarely fatal, but withdrawal reactions can be severe. People who discontinue benzodiazepines may experience symptoms of recrudescence, withdrawal, or rebound.
Recrudescence is the return of original severe insomnia.
Withdrawal symptoms usually occur after prolonged use and indicate dependence. They can last one to three weeks and are manifested by gastrointestinal distress, sweating, and arrhythmic heartbeats. In severe cases, patients might hallucinate or experience seizures, even a week or more after the drug has been stopped. Rebound symptoms are milder and include one to two nights of sleep disturbance, daytime sleepiness, and anxiety. Melatonin may significantly help many patients through withdrawal.