Glycolic Acid

Glycolic acid is the smallest and most-used alpha hydroxy acid, an exfoliant that loosens and removes dead surface cells to smooth texture and even tone. Its one well-established safety effect follows from how it works: by thinning the skin's outer layer, it leaves skin more sensitive to the sun. Regulators treat this as settled, which is why AHA products carry a sunburn alert and why daily sunscreen is part of using them. The effect is modest and reversible, with sensitivity rising about 18% after several weeks and fading within a week of stopping. Worth stating plainly, because the wording gets confused: more sun sensitivity is not the same as causing skin cancer, and when the FDA and National Toxicology Program tested glycolic acid under UV for exactly that, they did not find it to be a cancer-causer. The rest is dose. Safety bodies judge it safe up to 10% with an acidity floor, with stronger salon peels reserved for brief, professional, rinsed-off use. The hazard labels sometimes attached to glycolic acid, including a reproductive-harm warning, describe the concentrated raw chemical that factory workers handle, not the diluted few percent in a serum, where absorption is minimal and no such effect has been found. Pregnancy follows the same logic: low strengths are considered low-risk, strong peels are the ones to skip.