Side Effects of Glycolic Acid
In short
Most side effects come from using too much, too often, or on skin that wasn't ready.
Normal at first: brief tingling, mild dryness, some flaking as the surface adjusts. It settles within a week or two.
Not normal: burning, redness that lasts, stinging with everything you apply afterwards, skin still tight days later.
The one people underestimate is sun sensitivity. It's well documented, and it lasts about a week after your last use.
What's expected
These mean it's working, and they should fade.
Tingling for a minute or two after applying. Mild, and it stops.
Slight dryness in the first fortnight.
Light flaking as the surface renews faster than usual.
Skin looking slightly pink immediately after, settling within an hour.
How long it should last. Two weeks at most. If your skin hasn't settled by then, the strength or frequency is wrong.
What isn't
Stop and reassess if you get any of these.
Burning rather than tingling. Tingling is brief and mild. Burning isn't.
Redness that persists beyond an hour or two.
Stinging with products that were previously fine. A clear sign the barrier is damaged.
Tightness that lasts days.
Peeling in sheets rather than fine flaking.
Small bumps or breakouts in the treated area.
Darkening rather than lightening. The worst outcome. Upset skin makes pigment, so an over-used acid causes the marks it was meant to fade.
What to do: stop for two weeks. Gentle cleanser, moisturiser, sunscreen, nothing else. Then restart at half the frequency, or a lower strength.
Sun sensitivity
The side effect that causes the most long-term damage, and the least immediate discomfort.
What happens. Clearing surface cells faster leaves newer, less protected skin on top. Sun does more damage to it.
How long it lasts. About a week after your last application. Not just the days you use it.
What that means: daily sunscreen for as long as you're using glycolic acid, and for a week after you stop.
Why it matters more than it sounds. Using glycolic acid for dark marks? Unprotected sun undoes the work and adds more. People decide the acid failed. It never got a chance.
More in what does SPF mean.
Who reacts more
Easily upset skin. Lower strength, less often, and stop at the first sign of trouble.
Deeper skin tones. Not more delicate as such. But upset skin makes pigment more readily, so a reaction lasts longer. Start lower.
Damaged barriers. If ordinary products already sting, repair first. See what is the skin barrier.
Eczema or rosacea. Both flare with acids. Ask a doctor before starting.
Thin or folded skin. Underarms, neck, around the eyes. All react more than the rest of your face.
Anyone on a prescription retinoid. Together they irritate a lot.
How to avoid most of it
Start at 5% or below, not 10%.
Twice a week, building over a month.
At night, on clean dry skin.
Moisturiser afterwards, every time.
Sunscreen every morning, without exception.
One acid only. Not a glycolic toner under a salicylic serum.
Not on the same night as retinol. They don't react with each other. They both irritate, and together they damage the barrier.
Never on broken, shaved or sunburnt skin.
And patch test behind your ear or on your inner arm for three days before putting anything new on your face.
If you've overdone it
Stop completely. Not "reduce" — stop.
Two to four weeks of gentle cleanser, moisturiser, sunscreen. Nothing else.
Look for ceramides in the moisturiser. That's what your barrier is short of.
No actives at all until stinging has gone.
Then restart lower. Half the frequency, or a lower strength, and build more slowly than before.
How long recovery takes: most of it in two to four weeks. Longer if the barrier was badly damaged.
When to see a doctor
- Blistering or weeping skin
- Burning that doesn't settle within a day
- A spreading rash
- Darkening that continues after you've stopped
- Any reaction after a professional peel
Reactions to home-strength products are usually manageable at home. A reaction to a salon treatment needs whoever did it.
Frequently asked questions
What are the side effects of glycolic acid? Mild tingling, dryness and light flaking are normal at first. Burning, lasting redness and stinging with other products are not.
How long should tingling last? A minute or two after applying. If it's longer than that, or it burns, the product is too strong.
Is flaking normal? Fine flaking in the first fortnight is expected. Peeling in sheets isn't.
Does glycolic acid make you sun sensitive? Yes, and for about a week after your last use. Daily sunscreen isn't optional.
Can glycolic acid make pigmentation worse? Yes, if you overdo it. Upset skin makes pigment, so an over-used acid can darken the marks you're treating.
Why does my skin sting with everything since I started? That's a damaged barrier. Stop the acid for two to four weeks and use only a gentle cleanser, moisturiser and sunscreen.
Can I use glycolic acid with retinol? Not on the same night. Alternate nights instead.
How long does it take to recover from over-exfoliating? Two to four weeks for most people, longer if the damage was significant.
Should I patch test? Yes. Three days on your inner arm or behind your ear before using it on your face.
Is glycolic acid safe for sensitive skin? At low strength, used rarely, often yes. Lactic acid is gentler and worth considering instead.
For strengths, pH and what actually works at each level, see what is glycolic acid.
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