Coal tar has been used to treat psoriasis for more than 100 years. You can find it in shampoos as well as creams, oils, and lotions.
Shampoos with coal tar help with scaling, hardening, and thickening of the skin on your scalp by slowing down the growth of skin cells. They also can ease itching and make your scalp look better overall.
To use this kind of shampoo, massage it into your scalp, leave it on for 5 to 10 minutes, and then rinse.