Ativan belongs to a group of medicines called benzodiazepines. Lorazepam is believed to work by increasing the activity of certain neurotransmitters in the brain. Ativan is used to treat anxiety disorder.Ativan (lorazepam) is given by mouth. For best results, the dose, frequency of administration, and duration of treatment should be determined according to the patient's response. 0.5mg, 1mg, and 2mg pills are available to facilitate this. Ativan can be used alone or with other medications.