Over-the-counter (OTC) topicals are available in pharmacies, drugstores, supermarkets, or directly from the manufacturer without a doctor’s prescription. These treatments are available in many different varieties, such as lotions, foams, tars, bath solutions, shampoos, and more. Your health care provider can help you determine the best one for your psoriasis.
Two common active ingredients, salicylic acid and tar, are approved by the U.S. Food and Drug Administration (FDA) as treatments for psoriasis.
Salicylic acid is classified as a keratolytic, or peeling agent. It works by causing the outer layer of skin to shed. It is a common and effective treatment for a wide variety of skin problems. As a psoriasis treatment, it acts as a scale lifter, helping to soften and remove psoriasis scales.
Strong salicylic acid preparations can cause irritation if left on the skin for too long. Further, the body may absorb too much salicylic acid if used over large areas of the skin. Salicylic acid may also weaken hair shafts and make them more likely to break, leading to temporary hair loss. Please consult your health care professional if you experience any complications.
Tar derived from coal and wood (e.g., juniper and pine) is used for medicinal purposes. However, coal tar is most commonly used to treat psoriasis. Tar can help slow the rapid growth of skin cells and restore the skin’s smooth appearance. In addition, it can help reduce the inflammation, itching, and scaling of psoriasis. Tar products can vary dramatically from brand to brand. Generally, the higher the concentration of tar, the more potent the product.
Tar can irritate, redden and dry the skin. You should test a tar product on a small area of the skin first. If reddening occurs, try applying the tar on top of a moisturizer. Tar can stain clothing, bed linen, and light-colored hair. Tar can also make skin more sensitive to sunlight, so be sure to wash it off thoroughly, use sunscreen, and monitor your sun exposure. Tar remains active on the skin for at least 24 hours, so limit your time outdoors as you will be at an increased risk of sunburn during this period.
Studies show some of the chemicals in coal tar may cause cancer, but only in very high concentrations, such as in what is used in industrial paving. If you are using tar regularly, make sure to follow a regular skin cancer checkup schedule.
California requires OTC coal tar shampoos, lotions, and creams that contain more than 0.5 percent coal tar to be labeled with cancer warnings. However, the FDA maintains that OTC products with coal tar concentrations between 0.5 percent and 5 percent are safe and effective for psoriasis, and there is no scientific evidence that the tar in OTC products is carcinogenic.