Summer's Over. Your Skin Is Still Wearing It. A Doctor's Guide to Glycolic Acid

By autumn, many people notice their skin looks duller, feels rougher and has picked up uneven patches over the summer. Glycolic acid is one of the most studied ingredients for exactly this. It is also the same family of acid used at much higher strengths in clinic peels. Here's what it does, what the evidence shows, and how to use it without irritating your skin.

What is glycolic acid?

Glycolic acid is an alpha hydroxy acid (AHA). It is the smallest AHA, which means it moves into the outer layer of skin more easily than larger acids such as lactic or mandelic acid. It works by loosening the bonds that hold dead skin cells together, so they shed more evenly instead of building up on the surface (Tang and Yang, 2018).

What it can do for your skin

• Smoother texture, as rough build-up is cleared.

• Brighter-looking skin, because an even surface reflects light better.

• A more even-looking tone over time.

• Better results from the products you apply afterwards.

The evidence goes beyond surface polish. In a 22-week, double-blind trial, an 8% glycolic acid cream improved signs of sun damage compared with the same cream without the acid (Stiller et al., 1996).

Home toner or clinic peel?

A home toner uses a low concentration designed for regular use. A clinic peel uses a much higher strength and a lower pH, applied for a set time and then neutralised under supervision. The two do different jobs. At Hedonia, I use medical-grade chemical peels, including TCA peels, when skin needs more than home care can deliver, for example for stubborn pigmentation, sun damage or acne scarring. A home exfoliant is the maintenance between treatments, not a replacement for them.

The part the label won't tell you: sun sensitivity

Glycolic acid makes skin more vulnerable to UV. In a randomised, double-blind study, four weeks of 10% glycolic acid increased the number of sunburn cells after UV exposure and lowered the dose needed to make skin red. The effect disappeared within a week of stopping (Kaidbey et al., 2003). Another study found glycolic acid made skin tan more easily after UV exposure (Tsai et al., 2000). Autumn sun still counts. If you use glycolic acid, wear SPF every morning, such as a tinted SPF30.

How to use it

• Use it in the evening, on clean, dry skin.

• Start with two or three evenings a week and build up slowly.

• Don't combine it with a retinoid or another acid on the same night.

• Follow with moisturiser, and SPF the next morning.

• Stop if stinging or redness lasts. Irritation can trigger dark marks, especially in deeper skin tones.

• Avoid broken skin, and pause during a flare of eczema or rosacea.

Where Cutivance fits

Full disclosure: Cutivance is my own skincare range. The Glycolic Acid Exfoliating Toner contains 5% glycolic acid, with betaine and sodium PCA to help keep skin hydrated. It is designed to remove build-up and leave skin looking smoother and more even. It sits well in a simple evening routine after the Oil-to-Milk Cleanser and before the Moisturising Day Cream, with SPF every morning.

When to book a consultation instead

If you're dealing with pigmentation that won't shift, acne scarring or texture that home products haven't changed, a consultation will tell you whether a peel, microneedling or another treatment makes more sense.

Book a skin consultation

Frequently asked questions

Can I use glycolic acid every day?

Some people can, but most skin does better starting at two or three evenings a week. Increase slowly only if your skin stays comfortable.

Is 5% glycolic acid strong enough to work?

Yes, for home use. Low-strength glycolic acid used regularly smooths texture and brightens gradually. Higher strengths belong in clinic, where they are applied for a set time and neutralised.

Does glycolic acid make you more sensitive to the sun?

Yes. A controlled study found that four weeks of 10% glycolic acid increased UV damage in the skin, and the effect wore off within a week of stopping. Wear SPF every day while you use it.

Can I use glycolic acid with retinol?

Not on the same night when you're starting out. Use them on alternate evenings to reduce irritation.

Should I stop glycolic acid before an in-clinic treatment?

Usually, yes, for a few days before peels, microneedling and injectable treatments. I'll give you specific instructions when you book.

References

Kaidbey K, Sutherland B, Bennett P, et al. Topical glycolic acid enhances photodamage by ultraviolet light. Photodermatol Photoimmunol Photomed. 2003;19(1):21-7. PMID: 12713551.

Stiller MJ, Bartolone J, Stern R, et al. Topical 8% glycolic acid and 8% L-lactic acid creams for the treatment of photodamaged skin: a double-blind vehicle-controlled clinical trial. Arch Dermatol. 1996;132(6):631-6.

Tang SC, Yang JH. Dual effects of alpha-hydroxy acids on the skin. Molecules. 2018;23(4):863.

Tsai TF, Bowman PH, Jee SH, Maibach HI. Effects of glycolic acid on light-induced skin pigmentation in Asian and Caucasian subjects. J Am Acad Dermatol. 2000;43(2):238-43.

Written by Dr Adama Luca, BSc, BMBS (University of Southampton), MS Aesthetics (UCL), founder of Hedonia Medical Aesthetics, Salisbury. This article is general information, not personal medical advice.