Lorazepam (Ativan) is thought that excessive activity of nerves in the brain may cause anxiety and other psychological disorders. Gamma-aminobutyric acid (GABA) is a neurotransmitter, a chemical that nerves in the brain use to send messages to one another that reduces the activity of nerves in the brain. It is thought that lorazepam and other benzodiazepines may act by enhancing the effects of GABA in the brain to reduce activity. Because lorazepam is removed from the blood more rapidly than many other benzodiazepines, there is less chance that lorazepam concentrations in blood will reach high levels and become toxic. Lorazepam also has fewer interactions with other medications than most of the other benzodiazepines.