Hydrocortisone creams and ointments. You can buy a mild corticosteroid like hydrocortisone without a prescription. For a few small patches of psoriasis, a mild hydrocortisone works well. If you have more than a few small patches, you'll likely need a prescription corticosteroid to see results.

Coal tar is a medicine that's used on the skin and scalp to treat itching, irritation and dry patches (scaling and flaking). It also has some antibacterial properties. It comes as a cream, ointment, scalp lotion, shampoo or a liquid you add to your bath (emulsion additive).