Gl
Glycolic Acid
Glycolic AcidExfoliant
The classic exfoliating acid in toners and peels — loosens dead surface cells to smooth texture and even tone over weeks.
What it does
It’s the smallest of the common exfoliating acids, so it goes deeper than lactic or mandelic acid. Peels done in a clinic are stronger than store products.
The evidence, graded
expert consensusUse retinol and AHAs like glycolic or lactic acid on alternate nights, or the acid in the morning and retinol at night: the acid and the retinoid each irritate skin on their own. In the one study of the pair Drop's sources describe, retinol with glycolic acid improved photoaged skin more than either alone; it measured results, not comfort. Splitting them is a careful default, not a proven rule: no study Drop has read measured their irritation together.Mukherjee 2006 · Clinical Interventions in Aging ↗
expert consensusAlternate tretinoin and the acid by night, or split them across the day. Tretinoin is described as the most potent of the retinoids, more irritating than retinol, and acids irritate on their own. No study Drop has read applied the two to the same skin, so that they compound is a careful assumption, not a measurement.Mukherjee 2006 · Clinical Interventions in Aging ↗
expert consensusAdd an AHA and salicylic acid one at a time, within a safety panel's limits: AHAs under 10% at pH 3.5 or higher, salicylic acid under 3%. The review says salicylic acid is not a beta hydroxy acid and doesn't act like one, despite the label. In one study 10% glycolic acid made skin more sun-sensitive and 2% salicylic acid did not. No source Drop has read tested the two used together, so Drop can't tell you the pair is safe or that it isn't.Kornhauser 2010 · Clinical and Cosmetic Investigative Dermatology ↗
expert consensusBefore 25, with no skin condition to treat, Drop does not suggest high-strength acids (above 10%), strong retinoids or aggressive in-office treatments. This is Drop's cautious default, not a finding: no source it has read sets an age cutoff, and none tested these for preventing aging in people this young. If there is acne, melasma or another condition, a dermatologist may use them to treat it.Hughes 2013 · Annals of Internal Medicine ↗
expert consensusIn 2000 the EU’s cosmetics scientific committee (SCCNFP) found the data on AHAs too thin for a full safety assessment. On the precautionary principle, until the data were available, it suggested glycolic acid may be used safely at up to 4% and a pH of 3.8 or higher. It recommended warnings to avoid the eyes and to avoid or protect from UV. In 2004 it found that AHA use does increase UV damage to the skin, could not set a no-effect level, and kept its 2000 position.SCCNFP 2000 · European Commission SCCNFP ↗
expert consensusThe American Academy of Dermatology says ingredients like glycolic acid can help reduce oiliness, but they may be too harsh for your skin, and to stop or use the product less often if your skin becomes irritated. In a placebo-controlled split-face trial of 26 people with acne, five 40% glycolic acid peels lowered oil on both halves of the face, with no difference between the glycolic and placebo sides.AAD 2024 · AAD patient education (aad.org) ↗
emergingStart alpha arbutin and an exfoliating acid one at a time, with daily sunscreen: in one small study, skin pretreated with glycolic acid tanned more under UVB. Alpha arbutin blocks tyrosinase, the enzyme step that makes melanin. In cell studies glycolic and lactic acid block it too, whatever their acidity, so the acid clearing a path for the brightener is not what anyone measured. No study Drop has read applied the two to the same skin, so nothing measured says the pair helps or hurts.Maeda 1996 · Journal of Pharmacology and Experimental Therapeutics ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
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