sedative any of a variety of drugs that relieve anxiety. Most sedatives act as mild depressants of the nervous system, lessening general nervous activity or reducing the irritability or activity of a specific organ. Sedatives taken in small quantities are useful in relieving coughing, nausea, or convulsions and in lessening anxiety. In increasing doses sedatives act as hypnotics (see hypnotic drugs ), i.e., they induce sleep, and as anesthetics. Many sedatives, including barbiturates , meprobamate (Miltown), and benzodiazepines (Librium and Valium), are habit-forming and should be taken only under medical direction. Chloral hydrate, ethyl alcohol, bromide salts, and antihistamines can all be used as sedatives. Tranquilizers are compounds that calm without excessively reducing mental alertness.
