Overview
Salicylic acid is what scientists call a beta hydroxy acid, a naturally-occurring compound that breaks down dead skin cells. It is often put in medicated shampoos used to treat those lovely, white, powdery flakes you know as dandruff. Salicylic acid is found in the bark of willow trees and is chemically similar to what's in aspirin, according to Cosmeticsinfo.org, a website that provides scientific information about personal care products.
How it Works
Salicylic-acid shampoo works by breaking down the dry or scaly layer of scalp that produces dandruff flakes, according to Best Practices, a website that presents research evidence and expert medical opinions. That means salicylic acid is basically an exfoliant. If you can stick it on your face, you can also stick it on your scalp. Salicylic acid is approved by the Food and Drug Administration for use in shampoos and other personal-care products. Under the regulatory guidelines, it is not considered to be damaging to your hair.
Cautions
That doesn't means a salicylic acid shampoo will never cause your hair problems. Ladies, there are no free lunches on this planet. Medicated shampoos can have a drying effect, so if your hair is already dry or you use those shampoos frequently, do your hair a favor and follow up with some good conditioners. You can use a lighter one at the scalp level where there's more oil, and a stronger one for the middle and tips of your hair, according to TheBeautyBrains.com., a website that provides scientific answers to beauty questions.
Normal Flaking
Anti-dandruff shampoos may contain other active ingredient like sulfur and tar, plus the salicylic acid. Don't freak and rush to buy a medicated shampoo when you just see a few flakes of dandruff. That's a normal -- if not too cool -- thing that does not require a medicated shampoo. But if the flaking is really gross and your scalp is inflamed, that's different, and a visit with your doc might be a good idea.
Additional Info
Just don't push your luck and dry out your hair further with treatments that are known to damage your hair when you're using a salicylic acid shampoo. You've probably heard, the less chemical goop like dyes and relaxants you mess with and the less you reach for those hot irons, the better for your hair. Dry hair can break, so go easy on the hair brushing, too.

