For the Consumer. Applies to warfarin: oral tablet. Along with its needed effects, warfarin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. I was on Warfarin from 10/2011 until 5/2012. In Jan. or Feb. of 2012 my hair started coming out in big chuncks everytime I washed it. I stopped taking the medication in May of 2012 and about July or Aug.2012 my hair stopped coming out. Hair loss is a known side effect of warfarin (Coumadin®, Jantoven®), but has hardly been studied [ref 1]. Solid data on how frequently it occurs, on its time-course, and on treatments are not available. Mild hair loss appears to be common, severe hair loss uncommon, complete hair loss has not been reported. Talk to your doctor to determine if hair loss could be the result of an illness. Autoimmune diseases, diabetes and poor nutrition can all cause hair loss. Warfarin, especially if taken incorrectly, increases your risk of dangerous bleeding. Warfarin side effects can also include interactions with some foods, prescription medicines and over-the-counter supplements. In addition, you should not use warfarin if you have blood in your urine or stools, bleeding in your brain or stomach, or an infection in the lining of your heart. My hair is falling out. Is warfarin (Coumadin) to blame? Henry I. Bussey, Pharm.D., FCCP, FAHA January, 2006 Updated July 2007 Unfortunately, there is not much data on this issue, but some patients on warfarin (Coumadin) do report hair loss. Hello Dedeottie, it was so interesting to read your post as I was going to submit a very similar one. Yes, my hair is definitely thinning. I was put on Warfarin in May and noticed very soon after that I was losing quite a lot of hair. As Bob says, hair loss is a known side effect of warfarin though I don't think that many of us are afflicted. I feel your GP is being very unsympathetic. Using warfarin will I have hair.Yes, warfarin can cause hair loss (alopecia) and if warfarin is the only cause of your hair loss then hair loss should stop when you stop taking warfarin (which in some circumstances may be extremely difficult).