"SALICYLIC ACID FOR HAIR AND SCALP
TYPE OF INGREDIENT: Exfoliator
MAIN BENEFITS: Helps remove excess oil and dead cells from the surface of the skin
WHO SHOULD USE IT: Most people will benefit from salicylic acid-based haircare, especially those with a flaky, dry scalp and those with oily hair, says Williams. That being said, anyone with a sensitive scalp should proceed with caution.
HOW OFTEN CAN YOU USE IT: Williams says salicylic acid shouldn’t be used more than twice a week to avoid scalp aggravation and irritation.
WORKS WELL WITH: Follow up with moisturizing and hydrating products that feature ingredients like glycerin to help soothe any potential irritation.
DON’T USE WITH: Both doctors suggest sticking to one sort of exfoliating product at a time so as not to overwhelm the scalp."
https://www.byrdie.com/salicylic-acid-for-hair-5223426
"Rachel Westbay, 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."
https://www.whowhatwear.com/salicylic-acid-for-hair
"Salicylic acid works in shampoo by breaking down dead skin cells. This is scientifically proven to help treat conditions that affect the scalp, like seborrheic dermatitis and psoriasis. Other uses for the shampoo lack substantial evidence."
https://www.healthline.com/health/salicylic-acid-shampoo#_noHeaderPrefixedContent
"Salicylic acid works in shampoo by naturally stripping away the outermost layer of the skin (epidermis). This means it aids the removal of dead skin cells and product build up from the scalp and hair follicles, making it very popular in products that target dandruff (because dandruff is a build up of dead skin!).
In addition, it can also penetrate the pores deeply; it unclogs the follicles and clears them out which, in turn, prevents the scalp from overproducing oil. This can mean that the hair’s growth phase is less disturbed, allowing for healthier growth and reducing the chances of an irritated, greasy scalp occurring."
https://cel.md/blogs/news/salicylic-acid-for-hair