An elderly man taking warfarin notices his tablets are blue instead of brown and he started the new batch four days ago. He has bruising on his legs. What is the most appropriate advice?

• A. Stop warfarin and monitor
• B. Refer to A&E urgently
• C. Take vitamin K
• D. Reassure and continue

Answer: (B)

Warfarin requires careful monitoring because small changes in dose can dramatically affect bleeding risk. A change in tablet color often means a switch to a different brand or strength, which can unintentionally increase the anticoagulant effect. Bruising while on warfarin is a sign of possible bleeding and, in an elderly patient, indicates a potentially dangerous rise in anticoagulation. Because of these factors, urgent medical evaluation is needed to check the INR and adjust treatment as necessary. Do not stop warfarin suddenly, and do not take vitamin K unless advised by a clinician. Seek urgent assessment in A&E.