phenytoin and alcohol

Last reviewed 01/2018

Chronic heavy alcohol consumption of more than 30 units per day has been shown to reduce serum levels of phenytoin by about 1/3. In patients with only moderate or low alcohol consumption, no effect has been shown in serum phenytoin levels.

Phenytoin potentiates the effects of alcohol.

Patient advice (3)

  • It is recommended that you limit yourself to one or two units of alcohol per day. Half a pint of standard strength beer (4%) is 1 unit, one 175ml glass of wine (12%) is 2% and one single pub measure of spirits (40%) is 1 unit. Drinking may put you at risk of a seizure


  • Drugs and Therapeutics Bulletin (1996), Drugs and alcohol: harmful cocktails?, 34 (5), 36-8.
  • Hoppener RJ et al (1983), Epilepsy and alcohol: the influence of social intake on seizures and treatment in epilepsy, Epilepsia, 24, 459-71.
  • Nottingham University Hospitals NHS Trust (Accesed 4/5/2014). Phenytoin - Information for adults with epilepsy