There are two big guns used to take down acne, and they're both great at doing entirely different things. Salicylic acid is a beta hydroxy acid that comes from willow bark and works primarily as an exfoliator, breaking down fatty acids like sebum so your pores don’t clog. (Glycolic acid works similarly but is less effective.) These acids do their thing on comedones — whiteheads, blackheads, and other non-red bumps.
The approach to acne treatment underwent significant changes during the twentieth century. Retinoids were introduced as a medical treatment for acne in 1943. Benzoyl peroxide was first proposed as a treatment in 1958 and has been routinely used for this purpose since the 1960s. Acne treatment was modified in the 1950s with the introduction of oral tetracycline antibiotics (such as minocycline). These reinforced the idea amongst dermatologists that bacterial growth on the skin plays an important role in causing acne. Subsequently, in the 1970s tretinoin (original trade name Retin A) was found to be an effective treatment. The development of oral isotretinoin (sold as Accutane and Roaccutane) followed in 1980. After its introduction in the United States it was recognized as a medication highly likely to cause birth defects if taken during pregnancy. In the United States, more than 2,000 women became pregnant while taking isotretinoin between 1982 and 2003, with most pregnancies ending in abortion or miscarriage. About 160 babies were born with birth defects.
Acne appears when a pore in our skin clogs. This clog begins with dead skin cells. Normally, dead skin cells rise to surface of the pore, and the body sheds the cells. When the body starts to make lots of sebum (see-bum), oil that keeps our skin from drying out, the dead skin cells can stick together inside the pore. Instead of rising to the surface, the cells become trapped inside the pore.