Hi there, It is possible to develop a reaction to any sort of prescription medication. While it is more likely that the fenofibrate is the culprit, I agree that the vitamin D is also a suspect. Since the timing fits and you do suspect it, I would advise you to inform your doctor and stop the fenofibrate for a couple of weeks. Lipid-lowering medication are usually safe to temporarily stop, because the target of treatment is long term risk reduction, rather than the immediate effect. If the rash does go away, restart the offending medication to see if it triggers the rash again, as a confirmatory test. Then you would definitely have a solid reason to look for an alternative. If it doesn t improve, then move on to removing the vitamin D and see what happens. Hope this helps, and all the best to you. Regards, Dr. Teh