Hello. My Dad Is On Warfarine And Has Been Taking

Hello. My dad is on warfarine and has been taking manuka honey strength 13. Could this have affected his warfarine as a blood test was taken today and his level has gone up to 6.2 from 3.0 without taking anything else at all as not allowed. Honey was recommended because natural help for his very bad cold. Reason for asking...Drs called but just left a voice mail. Thank you.x