Phenobarbital is a medication that belongs to the class of drugs called barbiturates. It is used for the following purposes:

• Control seizures: Phenobarbital is used to prevent and control seizures in people with epilepsy.
• Relieve anxiety: Phenobarbital is used for a short time to help calm anxiety.
• Treat insomnia: Phenobarbital can be used to relieve insomnia.
• Manage withdrawal symptoms: Phenobarbital is used to prevent withdrawal symptoms in people who are dependent on another barbiturate medication and are going to stop taking the medication.
• Treat status epilepticus: Phenobarbital is recommended as an agent to treat status epilepticus.
• Treat benzodiazepine and alcohol withdrawal: Phenobarbital is useful for benzodiazepine and alcohol withdrawal treatment due to its anti-seizure properties and sedative effect.

Phenobarbital works by slowing activity in the brain and controlling the abnormal electrical activity in the brain that occurs during a seizure. It can be taken as a tablet or an elixir (liquid) by mouth, usually one to three times a day. Phenobarbital can be habit-forming, so it is important to take it exactly as directed by a doctor and not to take a larger dose, take it more often, or take it for a longer time than prescribed. Phenobarbital may cause side effects, and it is important to talk to a doctor if anxiety or seizure control worsens.