Glycolic acid in skin care is an alpha hydroxy acid, or AHA, used as a chemical exfoliant that loosens dead cells on the surface of your skin. It has the smallest molecule of the common AHAs, so it's often described as one of the stronger ones, which is why it's worth starting slowly.
What glycolic acid does in skincare
Your skin sheds old cells all the time. Some hang around on the surface. Your face can look a little dull, or feel rough when you run a finger along your cheek.
An exfoliating acid helps those cells let go. Glycolic acid does that at the surface. You'll find it in toners, pads, serums and night creams. On an ingredient list it's usually written simply as glycolic acid.
Is glycolic acid the same as lactic acid?
They're both AHAs and do a similar job. If you already use one, you probably don't need the other as well. For the gentler one, read what is lactic acid.
Is glycolic acid irritating?
It can be. The US Food and Drug Administration notes that AHAs can make skin more sensitive to the sun, and lists burning, irritation and peeling among the reactions people have reported. That's why the steps below start small.
How to start using glycolic acid
- Check your shelf first. Look for acids you already use. Lactic, salicylic, mandelic. A toner or a night cream might already contain one. If you're already exfoliating, a new bottle may be one too many.
- Patch test. Apply a little to a small area along your jaw for a few evenings. Watch for redness, itching or stinging that doesn't settle.
- Start with one or two nights a week. Evening is the usual time. Keep the other nights simple: cleanser and moisturiser.
- Apply to clean, dry skin. Then follow with a moisturiser your skin already likes.
- Wear sunscreen every morning. Skin can be more sensitive to the sun when you use AHAs, so this step matters.
- Check in the next morning. Comfortable? Carry on. Tight, flaky or stinging? Drop back to fewer nights.
- Build up slowly. If two nights a week feels fine for a few weeks, you can try a third. There's no need to use it every night.
Glycolic acid with other products
With retinol. Both can be a lot for many people. The common approach is to keep them on separate nights, with plain moisturiser nights in between. That's the idea behind skin cycling.
With another acid. Using a glycolic toner and a separate lactic or salicylic serum on the same night is doubling up. Pick one acid product and let it be the exfoliant on its night.
With a scrub. If you exfoliate with an acid, you probably don't need a gritty scrub on the same night.
Signs you're using too much
Your face might feel tight after washing. Moisturiser might sting when it usually doesn't. Your cheeks might look shiny and feel tender at the same time. Any of these is a cue to stop the acid for a week and go back to the basics.
If your skin stings, burns or stays red, stop using glycolic acid until it settles. If irritation keeps going, see a dermatologist or doctor.
If you want to space acids and other actives across the week, skin cycling exfoliation nights are a simple way to plan it.
Where Oleah fits
Oleah is an iPhone skincare companion. You add the products on your shelf or in your routine, take quick face scans to follow visible changes over time, and ask questions along the way. It can flag products that may not belong together. It does not diagnose or treat, and it does not sell skincare.
Glycolic acid FAQ
What is an AHA? An alpha hydroxy acid. It's a family of exfoliating acids that includes glycolic acid and lactic acid.
Is glycolic acid OK for sensitive skin? Some people with sensitive skin use it, and some find it too strong. Patch test first, start with one night a week, and stop if it stings.
Can I use glycolic acid with niacinamide? Many people use them in the same routine without trouble. If you notice stinging, use niacinamide in the morning and glycolic acid at night.
What does the percentage on a glycolic acid label mean? It tells you how much glycolic acid is in the product. The FDA notes that how much a product exfoliates also depends on its pH and other ingredients, so the number alone won't tell you how it will feel. Patch test whatever you use.
Do I need sunscreen with glycolic acid? Yes. Wear sunscreen every morning while you use any AHA.
