Do AHAs or BHAs really help against wrinkles and blemishes?
Both AHA (glycolic acid) and BHA (salicylic acid) demonstrably help against acne, blemishes and, to a lesser extent, wrinkles, although the effect varies from person to person. For acne, salicylic acid has the strongest evidence base, particularly for darker skin tones.
Glycolic acid (an AHA) and salicylic acid (a BHA) do genuinely help against wrinkles and blemishes, but the effect varies by application. For wrinkles and fine lines, a controlled trial in 44 women found that glycolic acid peels produced visible improvement in 30% of participants after 12 weeks of biweekly treatments. A BHA-related acid (capryloyl salicylic acid) performed slightly better (41%), but that difference was not statistically significant.
For acne and blemishes, the evidence is stronger. A comparative study in 44 acne patients showed that a combination peel of salicylic acid and mandelic acid (BHA) worked significantly better than a glycolic acid peel for both active breakouts and post-acne dark spots, and also produced fewer side effects. Salicylic acid peels are also particularly suitable for people with darker skin: they saw earlier and greater benefit than with glycolic acid, with a lower risk of complications. If you prefer a daily serum over a professional peel, more than 90% of 66 acne patients reported improvement after two weeks of using a combination serum containing both acids, but that study had no control group and relied on self-reporting.
A small study in 30 women tested a blend of AHA, BHA and PHA (a milder related acid) three times per week for 4 weeks. Wrinkles, pores, skin tone and texture all improved in a statistically significant way, including in participants with sensitive skin and without causing irritation. Because of the limited size and short duration, those results should be considered preliminary. PHAs, such as gluconolactone, deliver skin-improving effects comparable to AHAs but are milder, strengthen the skin barrier and are suitable for sensitive skin.
Side effects of AHA and BHA peels are generally mild: a burning sensation, temporary redness and irritation. Serious side effects are rare. At higher concentrations (professional peels), professional supervision is advisable, especially if you have sensitive skin or a darker skin tone. There is currently no scientific consensus on which acid and which concentration works best for which skin type or skin concern.
Evidence is based on multiple controlled studies and reviews, including one RCT. No meta-analyses are available. Study populations are relatively small (30-66 participants). Some studies lack a control group or rely on self-reporting.