Central nervous system (CNS) depressants include alcohol (in the form of ethyl alcohol), ethanol (beer, liquor, and wine), barbiturates (in the form of Amytal, Nembutal, Phenobarbital, Seconal, and Tuinal), benzodiazepines (in the form of Valium, Librium, Ativan, Serax, Xanax, Tranxene, and Klonopin), and other CNS depressants (such as Ambian, chloral hydrate, Meprobamate, Noludar, Paraldehyde, Placidyl, and Methaqualone). The substances are administered orally or with water in an injection.

Symptoms of depression of the CNS are the general behavior of a drunk (like incoordination, slurred speaking, and an unsteady gait), blurred mental clarity, impaired judgment, emotional lability, aggression, fatigue, and paranoid ideas. When an individual withdrawals from a CNS depressant, he/or she should be carefully watched to ensure that fatality does not happen because of seizures or delirium tremens.

There are four stages of CNS depression:

1. Stage one is the shakes - usually peaks a day or a day-and-a-half after the consumption of alcohol has ceased
2. Stage two is hallucinations - manifested in 25% of all patients with the shakes
3. Stage three is withdrawal seizures - grand mal, or full body, and they occur 7 to 48 hours after drinking
4. Stage four is delirium tremens - occurs 3 to 5 days after drinking