Depressants, used in small amounts, produce a sedative or calming effect.

Excessive use of this class of drugs induces symptoms like slurred speech, staggered gait, and altered perceptions.

Medically, these drugs are usually prescribed to aid in sleeping, relaxation and to relieve stress and irritability.

With these drugs, tolerance can quickly develop. Additional medication is required to achieve the effects experienced after initial use.

Depressants commonly seen by the laboratory include diazepam (Valium), alprazolam (Xanax), lorazepam, and clonazepam. Barbituates such as amobarbital and pentobarbital are occasionally seen as well.