If you've spent any time on TikTok lately (which, if you're like me, you sure have), you've probably seen the viral glycolic acid "hair hack" featuring The Ordinary's Glycolic Acid 7% Toning Solution. Videos racking up several thousands of views show the easy-to-use product helping remove dandruff from the scalp and hair—and I, of course, was intrigued from the jump, given how simple and direct this hack seems to be.
If glycolic seems familiar, that's because it is: It's an age-old dermatologist-recommended exfoliator for the skin. To learn what it can do for your strands, we spoke to board-certified dermatologists Marisa Garshick, MD, and Azadeh Shirazi, MD.
Meet the Expert
Ahead, find out everything you need to know about glycolic acid for hair.
Glycolic Acid for Hair
Type of ingredient: Exfoliant and moisture magnet
Main benefits: Exfoliates dead skin cells, promotes scalp renewal, lifts excess sebum, and maintains moisture in the hair. It helps the scalp renew itself, enhancing the overall health of the scalp and hair.
Who should use it: Generally, most people can use glycolic acid. However, it is most beneficial to those with oily and flaky scalps.
How often can you use it: Use glycolic acid once or twice a week to start, then lower your use to once a month over time. Be sure to consult a dermatologist to discuss what makes the most sense for your scalp.
Works well with: Glycolic acid pairs well with other exfoliating agents such as beta-hydroxy acids (like salicylic acid) or physical exfoliants.
Don’t use with: Avoid combining glycolic acid with vitamin C.
Benefits of Glycolic Acid for Hair
"Glycolic acid is an alpha hydroxy acid, an exfoliant that works to shift dead skin cells from the outer skin layers by dissolving and lifting substances that cause the dead cells to form clusters," explains Shirazi.
This can be particularly helpful for someone who is experiencing dandruff. "Dermatologists have been using it for decades in treating conditions such as seborrheic dermatitis or psoriasis," says Shirazi. "It’s also a moisture magnet, boosting hydration and your own natural supply of hyaluronic acid. More recently, it’s been shown to have antimicrobial effects, making it useful in reducing the yeast and bacteria that play a role in scalp acne or seborrheic dermatitis."
Other benefits of glycolic acid for hair include:
- Enhances scalp health: "Glycolic acid exfoliates off dead skin cells and allows for the scalp to renew itself, therefore enhancing the overall health of the scalp and hair," Shirazi says. "This process of cellular renewal boosted by glycolic acid is beneficial in scalp and hair aging."
- Removes excess oil: "Glycolic acid helps lift away excess sebum (oil) and dissolves product buildup, leaving [the hair and scalp] cleaner and fresher," Shirazi notes.
- Prevents hair breakage: "[Glycolic acid has] also been clinically shown to maintain moisture to strengthen hair and prevent hair breakage," Shirazi adds. "Adding it to hair care formulations nourishes and lubricates the hair, resulting in less tangling and friction, making it easier to brush and style."
- Prevents acne: "More recently, it’s been shown to have antimicrobial effects, making it useful in reducing the yeast and bacteria that play a role in scalp acne or seborrheic dermatitis," Shirazi shares.
Hair Type Considerations
Based on the benefits of glycolic acid, you may have gleaned that someone with dandruff or an oily scalp may be more inclined to pick up this ingredient. Shirazi confirms: "It’s particularly helpful in those with oily scalps."
When it comes to hair types, you'll first want to consider any scalp conditions, the experts note. "Be cautious if you have sensitive skin, open sores, hair loss, itchy scalp, or skin rashes," Shirazi says.
While some ingredients are universal with a low risk of irritation or damage, glycolic acid needs to be used with a little extra TLC. "Glycolic acid may not be beneficial for every skin or hair type, so consult with your dermatologist before using it," Shirazi explains. "It’s an acid, so long-term use can weaken the hair and lead to hair loss. It should be used in low concentrations and limited to one to two times weekly to start, then perhaps no more than monthly depending on the formulation you are using."
She continues: "For the scalp, using it one or two times a week is sufficient, as overuse will damage the scalp barrier and lead to unwanted reactions. Avoid using it if you have sensitive skin or have recently undergone any scalp or hair treatments such as straightening, relaxing, or perming the hair, and it's not great for color-treated or damaged hair."
How To Use Glycolic Acid For Hair
If your dermatologist recommends glycolic acid for your scalp, it's important to use it properly for optimal results.
The experts recommend once or twice a week, but no more than that. "Similar to how you would approach using an exfoliant on the skin, it is important to not over-exfoliate the scalp as this can contribute to irritation and dryness," says Garshick. It is also generally best to use glycolic acid at night time rather than during the day, as it can make your scalp and hair more sensitive to the sun.
In terms of application, you'll want to make sure to follow directions based on the product you apply to your scalp or hair. "Glycolic acid can be found in various scalp products including scrubs, serums, and masks as well as shampoos," Garshick says. "Some products are designed to be applied to the scalp and left on for 5-10 minutes prior to shampooing."