While case studies have shown that injectable forms of vitamin K1 can cause allergic reactions[1][2][3] and that high doses of vitamin K3 can cause hemolytic anemia in some people,[1] the consumption of vitamin K is not associated with adverse effects or toxicity in the general population.[4][1][5][6] That said, vitamin K does interact with some drugs, including blood-thinning drugs (anticoagulants) like warfarin and drugs that affect the intestinal absorption of dietary fat, such as colesevelam and orlistat. People who use such drugs should consult their doctor before considering using a vitamin K supplement or altering their dietary intake of foods rich in vitamin K.
What are vitamin K’s main drawbacks?
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•Last Updated: May 16, 2025
Vitamin K can cause allergic reactions with injectable forms, and high doses of vitamin K3 may lead to hemolytic anemia, but generally, its consumption is safe and is not associated with toxicity. However, it can interact with certain medications, particularly anticoagulants, so people who are taking these drugs should consult a doctor before changing their vitamin K intake.