Salicylic acid is a beta hydroxy acid used in skin cleansers, exfoliants, peels and masks. Well tolerated by different skin types, it is a close chemical cousin to acetylsalicylic acid, the active ingredient in aspirin. Though it is particularly effective in treating acne breakouts and is used to treat psoriasis and even dandruff, salicylic acid can cause unwanted side effects.
Normally, skin has a pH of between 4.5 and 6.0. Salicylic acid has a pH of 2.4, making it naturally more acidic than skin. Skin care product manufacturers manipulate a product’s effects by controlling the concentration of active ingredients and by adjusting the product’s pH. For example, a salicylic acid product meant for sensitive skin would have a lower concentration of salicylic acid than would a product meant for hardier skin types. Likewise, buffering agents would be included in a product meant for sensitive skin to adjust the product’s pH so that sensitive skin would not be damaged.
Exfoliants manually or chemically break the bonds that hold dead skin cells to the skin’s surface, so that fresher, younger-looking skin is revealed. Salicylic acid, when properly buffered, loosens dead skin cells without hurting living tissue. At higher concentrations, without buffering agents, the acid dissolves not only the cellular cement, but can harm living cells as well, thereby burning and possibly permanently scarring skin.
Though it is a popular ingredient and easily manipulated by cosmetic chemists, salicylic acid can cause lasting harm if improperly used. Its most commonly felt side effects are site irritation and stinging. The U.S. Food and Drug Administration is an globally recognized regulator for chemicals for human use, and its Cosmetic Ingredient Review Expert Panel concluded that the inclusion of salicylic acid in cosmetics is generally safe, “when formulated to avoid irritation and when formulated to avoid increased sun sensitivity”. It should not be used near open sores, around the delicate eye area, or on lips. Likewise, thin, sensitive skin may not tolerate salicylic acid and a patch test should be performed before full use to ensure that an individual’s skin can tolerate the acid.
Those sensitive to aspirin, or who are allergic to aspirin, may react to the topical application of salicylic acid. Indications of salicylism—a toxic reaction to salicylic acid—include headache, confusion, dizziness, ringing in the ears, general weakness, nausea and/or vomiting. The development of any of these symptoms requires a medical consultation.