AHA vs BHA: two acids, two different jobs

Reference: US Food and Drug Administration

What is the difference between AHA and BHA?

AHA and BHA are two kinds of acids used in skincare. AHAs, like glycolic acid and lactic acid, were tested in creams for skin worn by years of sun.

BHA in skincare usually means salicylic acid, which the US lists as an acne drug ingredient at 0.5 to 2%. They are different acids, tested for different jobs.

Reference: Stiller et al., 1996

Reference: US Food and Drug Administration

The letters are chemistry names. 🧪 A and B (alpha and beta) say where one small part sits on the molecule.

Two acids, one letter apart. Like squalane and squalene all over again!

Here is what the AHA study found. 74 women aged 40 to 70 used a cream twice a day for 22 weeks: 8% glycolic acid, 8% lactic acid, or a plain cream.

On the face, 76% of the glycolic group and 71% of the lactic group got at least one step better on a sun-damage scale. With the plain cream, 40% did. 📈

Reference: Stiller et al., 1996

The improvement was limited. This study does not promise a large change for every face.

So 8% is the amount that was tested. A cosmetic label lists ingredients from the biggest amount down, and it does not have to show percents.

Reference: US Food and Drug Administration, 2016

So most labels can't tell you if a cream reaches 8%. You'd have to ask the brand.

Which one is for oily or acne-prone skin?

Salicylic acid (BHA) is on the US acne drug list at 0.5 to 2%. It is sold without a prescription under those rules.

Glycolic acid and lactic acid (AHAs) are not on that list.

The AHA cream study in this post was about sun-worn skin, not acne.

Reference: US Food and Drug Administration

That's about the ingredient, not about any one bottle. 🫧 A product still has to reach that amount.

Want the full picture for your skin? The acne, large pores and oily skin pages show which ingredients PERBETE lists higher for each.

Why does an AHA make skin burn faster in the sun?

In a US study, 29 people put 10% glycolic acid on their backs for 4 weeks. After that, their skin reddened at a lower dose of UV light and made more sunburn cells.

One week after they stopped, the difference was gone. So sunscreen matters while you use an AHA, and for a week after.

Reference: Kaidbey et al., 2003

The US FDA sums it up in numbers. ☀️ Skin got about 18% more sensitive to reddening, and sun-damaged cells about doubled.

It asks AHA products to tell you to use sunscreen while you use them and for a week afterwards.

Reference: US Food and Drug Administration

It went away a week after stopping. So it's a "wear your sunscreen" thing, not a "never use it" thing.

That study tested glycolic acid only. A matching sun test for salicylic acid is not in the studies PERBETE has on file yet.

The FDA reports conditions for glycolic and lactic acid use at home: 10% or less, and pH 3.5 or higher. Sun-protection directions are also needed.

These conditions are not a promise that every bottle suits every person.

Reference: US Food and Drug Administration

pH is a number for how acidic a product is. 🔢 Lower means more acidic.

Is salicylic acid a drug in the US?

At 0.5 to 2% for acne, yes. In the US, salicylic acid at that strength is an over-the-counter acne drug ingredient. A product sold that way has a Drug Facts box.

The box names salicylic acid as the active ingredient and shows its percent. The other ingredients are listed in the same box.

Reference: US Food and Drug Administration

Reference: US Food and Drug Administration, 2011

So a salicylic acid product can come two ways. 📦 With a Drug Facts box, you see the percent. In a plain ingredient list, you usually don't.

Drug Facts box = you see the percent. Plain list = usually not.

And outside the acne drug rules? An expert panel found salicylic acid safe in cosmetics when the product is made so it does not irritate skin or cause allergies.

Reference: Johnson et al., 2025

Can you use AHA and BHA together?

A study of the two used together is not in the studies PERBETE has on file yet. Lots of products already put both in one bottle.

On October 19, 2026, 226 products in PERBETE's catalogue listed both glycolic acid and salicylic acid. Both are acids, and acids can sting, so add one at a time.

PERBETE counted. 🧮 On October 19, 2026, its catalogue had 25,597 skincare products with an ingredient list.

If you already use one acid, check your other bottles before you add another.

How do you spot them on an ingredient list?

Look for the names. AHAs show up as glycolic acid or lactic acid. BHA shows up as salicylic acid.

If the product is sold as an acne drug, also look in the Drug Facts box, where salicylic acid is listed as the active ingredient with its percent.

Reference: US Food and Drug Administration, 2011

One trap. 🕵️ "BHA" on a label can also stand for butylated hydroxyanisole. That is a different ingredient, not the acid. Read the full name, not just the letters.

Each acid has its own page: glycolic acid, lactic acid and salicylic acid.

For rough, bumpy skin, see the textured skin page. More label tricks are in how to read a skincare ingredient list.

Try it on a product you own with the ingredient checker. ✨ For a routine built from your own skin answers, take the free skin quiz.