There’s a good chance you’ve swiped salicylic acid onto your face as part of your skincare routine. It’s a miracle worker when it comes to fighting acne and exfoliating skin. That’s because it’s a BHA, which means that it’s an oil-soluble form of hydroxy acid, so it’s able to penetrate deep into your skin’s pores.
One thing you might not know is that salicylic acid is also a great ingredient to add to your haircare routine. You might feel iffy about putting acid on your scalp, but it’s worth it—keep reading to find out why.
Rachel Maiman, MD, FAAD, board-certified dermatologist at Marmur Medical says that salicylic acid gives the most benefits to the scalp rather than the hair itself. Since it improves scalp health, however, salicylic acid may also support hair growth since it’s creating a better environment for hair to grow in.
When it comes to scalp health, salicylic acid is particularly useful if you struggle with dandruff. “Because salicylic acid is a keratolytic agent, meaning it exfoliates dead skin cells by breaking cell-to-cell adhesion, it can remove scaly, flaky skin and thus improve the appearance of dandruff,” says Maiman. Since buildup of dead skin cells can cause your scalp to itch, salicylic acid can also help relieve itchiness.
“Salicylic acid significantly benefits the scalp,” says Shab Reslan, NYC trichologist and hair expert “Having a balanced scalp is the first step to having healthy hair, and can impact hair growth and loss.”
If you have oily hair, salicylic acid will help mitigate some of that oil. “As salicylic acid has a particular affinity for oil, it is incredibly effective at reducing oil on the scalp surface,” says Maiman. “This is a benefit because seborrheic dermatitis—the medical condition known to the public as ‘dandruff’—is largely caused by a yeast called Malassezia furfur that requires oil to survive. Also, by stripping away the outermost layer of the epidermis, salicylic acid allows oil, dead skin, and product buildup to be washed away.”
Any hair type can use salicylic acid, but you’ll get the most benefit from the BHA if you have oily hair or a dry, flaky scalp. Maiman recommends skipping this ingredient if you have sensitive skin unless you ease into it gradually or do a patch test. “I also would advise against using it if the skin on the scalp is broken, irritated, or compromised,” she adds.