Which substances should be avoided while on warfarin?

Which substances should be avoided while on warfarin?

• A. Water and bread
• B. Aspirin and alcohol
• C. Vitamin C and calcium
• D. Caffeine and sugar

Answer: (B)

Warfarin’s effect is highly sensitive to substances that increase bleeding risk or alter how the drug is metabolized. Aspirin adds an antiplatelet effect, which together with warfarin markedly raises the risk of serious bleeding. Alcohol can modify liver enzymes that metabolize warfarin, potentially increasing the anticoagulant effect and the chance of bleeding, especially with chronic use. The other options don’t have meaningful interactions with warfarin in typical practice. So, avoiding aspirin and alcohol is the best choice.

Warfarin’s effect is highly sensitive to substances that increase bleeding risk or alter how the drug is metabolized. Aspirin adds an antiplatelet effect, which together with warfarin markedly raises the risk of serious bleeding. Alcohol can modify liver enzymes that metabolize warfarin, potentially increasing the anticoagulant effect and the chance of bleeding, especially with chronic use. The other options don’t have meaningful interactions with warfarin in typical practice. So, avoiding aspirin and alcohol is the best choice.