Acamprosate is a medication for people in recovery who have already stopped drinking alcohol and want to avoid drinking. It works to prevent people from drinking alcohol, but it does not prevent withdrawal symptoms after people drink alcohol. It has not been shown to work in people who continue drinking alcohol, consume illicit drugs, and/or engage in prescription drug abuse. The use of acamprosate typically begins on the fifth day of abstinence, reaching full effectiveness in five to eight days. It is offered in tablet form and taken three times a day, preferably at the same time every day. The medication’s side effects may include diarrhea, upset stomach, appetite loss, anxiety, dizziness, and difficulty sleeping.