Salicylic acid vs glycolic acid: how they differ

Salicylic acid and glycolic acid sit next to each other on the skincare shelf, often labeled BHA and AHA. Both remove dead skin cells from the surface of the skin, a process called exfoliation. They differ in where they work, in how they affect sun sensitivity, and in how the FDA treats them for acne. This guide compares them point by point. For the full picture of salicylic acid, see the hub guide, what salicylic acid does for your skin.

The short comparison

	Salicylic acid	Glycolic acid
Label group	BHA (beta hydroxy acid)	AHA (alpha hydroxy acid)
Dissolves in	Oil and fat	Water
FDA over-the-counter acne ingredient	Yes, 0.5 to 2 percent	No
Strength in cosmetics	Below 3 percent (2010 review)	10 percent or less, pH 3.5 or higher (limits the FDA describes)
Sun sensitivity in a 2009 human study	No significant change at 2 percent	Increased at 10 percent
FDA sun advice	Use sun protection	Sunburn Alert statement recommended

Two acids from two families

The FDA says the most common AHAs in cosmetics are glycolic acid and lactic acid. A 2010 review by a retired FDA scientist calls glycolic acid the simplest AHA and the first one added to skincare products. The FDA describes what AHAs do: they "cause exfoliation, or shedding of the surface skin," and the amount depends on the type of acid, its strength, its pH and the other ingredients.

Salicylic acid is sold as a BHA. The FDA says it is the BHA most commonly used in cosmetics, and adds that, from a chemist's view, it is not a true BHA. The guide what is salicylic acid explains that label detail.

Oil versus water

The difference that matters most for acne is what each acid dissolves in. A 2015 review in Clinical, Cosmetic and Investigational Dermatology says salicylic acid is "a lipid-soluble agent, in contrast with the α-hydroxy acids (such as glycolic acid)." Lipid means fat or oil. Because it dissolves in oil, the review says, salicylic acid mixes with the oil in the skin's surface and in the oil glands inside hair follicles. A pore is the opening of a hair follicle, and a clogged pore is filled with oil and dead skin. The 2010 review says the same: salicylic acid is fat soluble, "which makes it useful in subjects with oily skin."

Glycolic acid works on the surface. The AAD's page on oily skin puts the two together and adds lactic acid: "Ingredients like salicylic acid, glycolic acid, and lactic acid can help reduce oiliness, but they may be too harsh for your skin." So both can help oily skin, and both can irritate it.

Which one the acne rules include

In the United States, the FDA's rules for over-the-counter acne products list the active ingredients a product may contain. Salicylic acid at 0.5 to 2 percent is on that list. Glycolic acid is not. A glycolic acid product can still be sold as a cosmetic for skin texture, but it cannot be labeled as an acne treatment under those rules.

The 2024 acne guideline from the Journal of the American Academy of Dermatology gives salicylic acid a conditional recommendation. The American Academy of Dermatology (AAD) explains that a conditional recommendation applies to most patients, "but the most appropriate action may differ depending on individual patient factors." The AAD's page on adult acne says salicylic acid "works best on whiteheads and blackheads."

So for acne, salicylic acid is the acid with a legal acne label and guideline support. The strongest over-the-counter options in the 2024 guideline are still benzoyl peroxide and topical retinoids such as adapalene. See salicylic acid for acne for how salicylic acid compares with those.

Head to head in a study

One small study compared the two acids directly as office peels. In a 2008 study in Dermatologic Surgery, 20 people with mild to moderately severe acne had a 30 percent glycolic acid peel on one half of the face and a 30 percent salicylic acid peel on the other half, every 2 weeks, six times. Neither the patients nor the person counting the pimples knew which side got which acid. Both peels worked by the second treatment, with no significant difference between them. Two months after the last peel, the salicylic acid side had kept its results, and the glycolic acid side had more side effects after the first treatment.

This study used 30 percent peels, 15 times the 2 percent maximum in home acne products, and it had 20 people. Its result applies to office peels in that group. None of the sources Skinli read compared a 2 percent salicylic acid wash with a glycolic acid toner. The 2024 AAD acne guideline found the evidence on chemical peels too limited to make a recommendation.

Sun sensitivity

The two acids differ most on sun sensitivity. The FDA says its research found that "applying AHAs to the skin results in increased UV sensitivity." After four weeks of AHA use, volunteers' skin reddened 18 percent more easily under UV light. One week after they stopped, the difference was gone. The FDA recommends a Sunburn Alert statement on AHA products that tells users to use sunscreen, wear protective clothing and limit sun while using the product and for a week afterwards.

Salicylic acid tested differently. In a 2009 study in the Journal of Dermatological Science, 14 people had test areas on the back treated five days a week for 3.5 weeks with 10 percent glycolic acid, 2 percent salicylic acid, or a plain base. Glycolic acid increased redness, DNA damage and sunburn cells after exposure to light that copies sunlight. "Salicylic acid did not produce significant changes in any of these biomarkers."

Keep using sunscreen with salicylic acid anyway. The FDA advises: "Use sun protection if you use a BHA product." Other acne treatments you may use alongside, such as adapalene and benzoyl peroxide, carry their own sun warnings on the label.

Irritation

Both acids can sting and dry the skin. The FDA's BHA page repeats a claim that BHAs improve skin texture "without the occasional irritation associated with the use of AHAs," but it presents that as a claim that has been made, and the FDA gives the same precautions for both: test on a small area first, follow the label, do not exceed the recommended use, and stop and see a doctor if irritation or stinging does not go away. The AAD's oily skin page says to stop the product or use it less often if your skin becomes irritated.

For glycolic acid cosmetics, the FDA describes the safety limits set by an industry panel: 10 percent or less, with a final pH of 3.5 or higher. A lower pH means a stronger acid on the skin.

For salicylic acid acne products, MedlinePlus gives a simple way to limit irritation: apply the product less often at first, then more often once your skin has adjusted. If your skin becomes dry or irritated at any point, apply it less often again. The FDA's acne label directions say the same in numbers: start once a day, and drop to once a day or every other day if dryness or peeling bothers you.

Using both

Many people ask whether they can use salicylic acid and glycolic acid together. Each one can irritate the skin on its own, and the FDA's precautions for AHAs and BHAs start with a test on a small area. Skinli's guide to using an AHA and a BHA together answers that question, and which skincare ingredients you can mix covers the other common pairs.

If you use a leave-on salicylic acid acne product, also check the label of any adapalene gel you use. The adapalene Drug Facts label says irritation is more likely "if using more than one topical acne medication at a time," and its leaflet says to avoid products with alpha hydroxy or glycolic acids on the skin you treat, because they may make irritation worse.

Which one to pick

• Clogged pores, blackheads and whiteheads, oily skin: salicylic acid, at 0.5 to 2 percent in a product labeled for acne.
• Rough or dull skin texture with no acne: glycolic acid is the more common choice in cosmetics, with daily sunscreen.
• Red, painful or deep pimples: neither acid is the right first step. The AAD says large, painful pimples deep in the skin need a dermatologist.

Start with one acid, once a day or less, inside a simple routine like the complete acne skincare routine, and give it 6 to 8 weeks, as the AAD advises for any new acne product. See how to use salicylic acid on your face for the steps, and how to patch test a new skincare product before your whole face.