Hello, You should stop taking the supplement. Taking excess of the supplements more than the body requires will cause harm not good. Your body requires only 17mg a day of Niacin(B3). Taking more than that will cause itchy, scaly skin. Since you have taken it for a prolonged period of time your symptoms may take some time to reduce. Do not haste have patience. Take bath regularly. Wear soft loose fitting cotton clothes. Do not touch, scratch or pick. Do not use harsh chemical beauty products and lotion. Use gentle herbal products. Do not use expired products. You can apply a thin layer of ointment hydrocortisone on the area affected. Take antihistamines at bed time, it will help to reduce symptoms of allergy, itching and inflammation. If painful then you can take acetaminophen after food to help reduce soreness, redness and inflammation. Your symptoms should reduce. If symptoms remain persistent then get clinically examined by a dermatologist. You need to get a course of corticosteroids. You may be asked to get a skin test done like patch test, skin prick test, intradermal test. You will be treated accordingly. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician