Patients should never apply other topical medications to the skin being treated with salicylic acid unless instructed to do so by their doctors, according to Mayo Clinic. Abrasive soaps or cleaners and skincare products containing alcohol can irritate skin treated with salicylic acid, adds MedlinePlus.
Children and teenagers who have the flu or chickenpox should not use salicylic acid because there is a risk of developing Reye's syndrome, a disorder that causes fat to build up in the brain, liver and other body organs, according to MedlinePlus.
Common side effects of salicylic acid include skin irritation and localized stinging, states MedlinePlus. Hives, itching, difficulty breathing, and swelling of the face, lips or tongue indicate a rare, severe allergic reaction requiring emergency medical attention.