warfarin and alcohol

Last reviewed 01/2018

The half-life of warfarin is reduced in heavy chronic drinkers. However patients with liver dysfunction who are well-controlled on warfarin may become overanticoagulated after an alcoholic 'binge'.

Patient advice (2)

  • it is dangerous to binge drink or get drunk while taking warfarin. Doing this may increase the effect of warfarin and so increase the risk of bleeding

  • do not drink more than three units of alcohol a day if you are a man or two units a day if you are a woman
    • it is not safe to save up units to have on one day

  • one unit is roughly equivalent to half a pint of beer or lager or a single measure (25ml) of a spirit such as vodka. A small glass (125ml) of wine is around 1.5 units

  • people with liver disease who are taking warfarin should not drink alcohol


  • Drugs and Therapeutics Bulletin (1996), Drugs and alcohol: harmful cocktails?, 34 (5), 36-8.
  • NHS Choices (accessed 4/5/2014).Anticoagulants, warfarin - Interactions