My in-laws live with us and my father-in-law is always cold. He is on Plavix. When he complains about feeling cold, his skin is not cold. Why is he feeling cold? Turning the heat up doesn't really help unless it is so hot that the rest of us can't breathe. What I really want to know is why do blood thinners make you cold? If they increase circulation, they should make you feel warmer.