These drugs are sold in capsules and tablets or sometimes in a liquid form or suppositories. The effects of barbiturates are, in many ways, similar to the effects of alcohol. Small amounts produce calmness and relax muscles. Somewhat larger doses can cause slurred speech, staggering gait, poor judgment, and slow, uncertain reflexes. These effects make it dangerous to drive a car or operate machinery.
Large doses can cause unconsciousness and death.
These include suicides and accidental drug poisonings. Accidental deaths sometimes occur when a user takes one dose, becomes confused and unintentionally takes additional or larger doses. With barbiturates there is less difference between the amount that produces sleep and the amount that kills. Furthermore, barbiturate withdrawal can be more serious than heroin withdrawal. All the other sedative-hypnotics can be abused, including the benzodiazepines.