What does glycolic acid do for skin?

What glycolic acid does in skin

Glycolic acid is an alpha hydroxy acid, or AHA, found in sugar cane. AHAs dissolve in water and work mainly at the skin surface. Glycolic acid is the smallest AHA, so it penetrates skin more easily than other AHAs and helps loosen surface cell connections. That shedding is exfoliation: dead surface cells are loosened and shed. Glycolic acid is the smallest AHA, a fact about molecular size rather than a license for the rest of the shelf. The process can also unclog pores.13

With high concentrations or longer use, glycolic acid can affect deeper skin layers. Research describes effects on collagen production, hyaluronic acid in the epidermis and dermis, elastic fibers, and melanin production.23

What results are realistic

Glycolic acid is used to improve rough or uneven texture, fine lines and wrinkles, uneven tone, and the appearance of dark marks left by mild sun damage or acne. It can also clear clogged pores; possible benefits include fewer blackheads and breakouts. A cosmetic product that makes these claims is not necessarily an acne treatment: the FDA considers products intended to treat acne or lighten skin to be drugs.124

Home products take patience. With over the counter glycolic acid, brighter skin or more even pigmentation may take several months of consistent use to notice. In office peels use higher concentrations and can produce more dramatic changes, but they are procedures, not evidence that a stronger acid belongs in a nightly home routine.1

One laboratory study helps explain the mechanism, but it did not test a normal skin care routine. Researchers applied glycolic acid formulas at 8 to 25 percent and pH 4 to human skin explants, meaning skin tissue kept outside the body, each morning for five days. Shedding increased with concentration, and collagen levels rose at every strength. The tissue came from one surgical donor, with four explants per treatment group. This demonstrates an effect in the tested tissue, not a long term result for people using a home product.2

How strength depends on the formula

The percentage is not the whole formula. The amount of free acid, pH, time on skin, and product base affect penetration; the type of acid and other ingredients also affect how much exfoliation happens. Most glycolic acid products made for home use contain lower concentrations and are partially buffered to a pH around 4. A percentage on the label is the headline; pH and the rest of the formula are the editors.24

The FDA summarizes an industry safety panel's conclusion that consumer glycolic acid products are safe when the concentration is 10 percent or less, the finished formula has a pH of at least 3.5, and the formula or directions address sun sensitivity. These are conditional criteria, not a promise that every product will suit every person. Higher concentrations and lower pH are linked with more irritation.4

How to use glycolic acid

1. 1Test a small amount on one area of skin and see how it reacts.
2. 2Apply it at night. Start once or twice a week, then increase slowly toward nightly use only if your skin tolerates it.
3. 3When starting, avoid using it with other exfoliating acids, retinol, or vitamin C. Introducing one new active at a time makes it easier to identify what caused irritation.
4. 4During the day, use sunscreen with SPF 30 or higher and reapply every two hours. Wear protective clothing and limit sun exposure while using an AHA and for one week after stopping.

AHAs can increase sensitivity to ultraviolet light. In studies reviewed by the FDA, redness sensitivity rose by 18 percent after four weeks of use, and sensitivity to ultraviolet related cell damage doubled on average. One week after treatment stopped, researchers found no significant differences in sensitivity between the tested skin sites.4

Professional glycolic peels are stronger than home products. DermNet describes superficial peels using 20 to 70 percent glycolic acid, with strength chosen for skin sensitivity and treatment starting gently. The solution is applied for three minutes and washed off; mild stinging, pinkness, and some peeling over the next few days can follow. A lunchtime peel is still a chemical peel, even if the name seems to promise a sandwich.3

Chemical peel risks differ by skin tone. People with darker skin have a higher risk of unwanted pigment changes and raised or keloid scars after peels, so peel strength and skin history need careful assessment. This caution concerns chemical peels.5

Who should be careful with glycolic acid

Use caution if you have sensitive or dry skin, rosacea, eczema, an active skin infection, or skin that is not healing, since glycolic acid can add irritation. Low concentration glycolic acid is generally considered safe during pregnancy, but check with a health care provider before use if pregnant or breastfeeding.1

Glycolic acid side effects

At home use can cause irritation, dryness, and increased sun sensitivity; higher concentrations and lower pH raise the chance of irritation. FDA reports for AHA products include burning, rash, swelling, blisters, peeling, itching, and pigment changes. Stop using a product that causes persistent burning, severe redness, swelling, blisters, or an ongoing rash, and seek medical advice for a severe or persistent reaction.124