Over a year ago I suddenly began experiencing an unusual itching. Then I learned that too much niacin can cause itching. "But I'm not taking that much," I thought regarding the small niacin supplement I'd been taking for a couple of months. However upon more research, I discovered that niacin is also an ingredient in my supplements for blood pressure and cholesterol. I stopped taking the extra niacin and the itching went away. Like many things, some is beneficial or even necessary, but too much equals a problem. So I'd advise your checking anything you're ingesting or using.