Salicylic acid, which comes from the willow tree, is a beta hydroxy acid. It can be used in topical treatments to soothe joint and muscle pain. It is also used in ointments, creams and gels to improve a variety of skin conditions that include acne, psoriasis, calluses and warts.

Salicylic acid helps open pores, shed dead skin cells and neutralizes bacteria.  As a result of this exfoliating effect, new skin cells are allowed to grow back unhindered.

Salicylic acid or coal tar are the main active ingredients of many over the counter topical psoriasis medications.  Both ingredients are common in several shampoos developed to treat dandruff as well as scalp psoriasis.

Salicylic acid by itself is not a direct treatment for psoriasis, but it is used to help other medications reach the live, younger skin that is inflamed, below the surface by dissolving the dead skin or psoriasis plaque build up on the surface.  Thus, salicylic acid can be used to complement other topical treatments designed to treat mild to moderate psoriasis symptoms.

Salicylic acid can also be applied as a preparation for UV light therapy for moderate to severe cases. If lesions associated with psoriasis become infected by various types of growths this ingredient is also used as an antiseptic and disinfectant. Concentration levels vary by use.

The percentage of concentration in over the counter products for psoriasis is usually about three percent.  In excessive concentrations it can irritate the skin.  The fact that wart removers may contain up to 17% salicylic acid gives you an idea of how potent salicylic acid can be.

In some cases salicylic acid can actually increase, rather than decreases skin inflammation (though nothing like this has ever happened to me).

Products that combine this ingredient with sulphur are not approved for the treatment of psoriasis. The FDA considers this an effective treatment for dandruff only. Moisturizers containing this ingredient should be applied immediately after bathing for best results.

Note: Using moisturizers throughout the day can control psoriasis symptoms between treatments. Though the FDA has deemed salicylic acid safe, there are some safety considerations to keep in mind. Use sparingly, for brief periods on young children as they are more likely to develop skin irritations. Read the instructions for use carefully. Do not exceed the recommended dosages when referring to concentration and length of treatment. This could result in adverse side effects that include severe skin irritation and poisoning. The treatments containing this ingredient are meant for topical use only. Using in or near the mouth, nose or eyes could result in over absorption by the skin.

Neutrogena’s T/Sal is a common over-the counter salicylic acid shampoo, which I use on a regular basis with very good results.