Phenobarbital is a long-acting barbiturate and the most widely used anticonvulsant worldwide, and the oldest still commonly used. It also has sedative and hypnotic properties, but as with other barbiturates, it has been superseded by the benzodiazepines for these indications. The World Health Organization recommends its use as first-line for partial and generalized tonic���clonic seizures in developing countries. It is a core medicine in the WHO Model List of Essential Medicines, which is a list of minimum medical needs for a basic health care system. In more affluent countries, it is no longer recommended as a first- or second-line choice anticonvulsant for most seizure types, though it is still commonly used to treat neonatal seizures. Phenobarbital is manufactured and supplied in various forms: in tablets of 15, 30, 60 and 100 mg; in an oral elixir; and in a form for injection. The injectable form is used principally to control status epilepticus, while the oral forms are used for prophylactic and maintenance therapy. The dose range for epilepsy is 60���320 mg/day; its very long active half-life means for some patients, doses do not have to be taken every day, particularly once the dose has been stabilised over a period of several weeks or months, and seizures are effectively controlled. It is occasionally still used as a sedative/hypnotic in anxious or agitated patients who may be intolerant of or do not have access to benzodiazepines, neuroleptics and other, newer drugs. For this purpose, phenobarbital has a lower dose range - around 30���120 mg/day, but this practice is uncommon in developed countries.