Vitamin K

Which other medicines affect vitamin K?

Updated 3 Nov 2026

Short answer

Antibiotics, some cholesterol medicines and the weight-loss medicine orlistat can lower vitamin K in the body.[1]

  • Antibiotics can kill the gut bacteria that make vitamin K. Cephalosporins such as cefoperazone may also block its action. Supplements are usually needed only after several weeks of antibiotics with a diet low in vitamin K.[1]
  • Bile acid sequestrants, cholesterol medicines such as cholestyramine and colestipol, can lower the absorption of vitamin K.[1]
  • Orlistat lowers the absorption of fat and of fat-soluble vitamins such as vitamin K. Taken with warfarin, it may make blood take much longer to clot.[1]

People who take these medicines for a long time should ask a doctor or pharmacist about their vitamin K status.[1]

Sources (1)

  1. Vitamin K: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov

More about vitamin k

What is vitamin K?Which foods contain vitamin K?What is vitamin K used for?Who is at risk of vitamin K deficiency?Is vitamin K safe?Why do newborn babies get vitamin K?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.