Glycolic acid or lactic acid for dry skin?

What is the difference for dry skin?

If your main concern is dry, rough skin, start by considering lactic acid rather than reaching straight for glycolic acid. The aim is smoother skin, not an exfoliation contest judged by the bottle. Glycolic acid is worth considering when uneven pigmentation or fine lines are also priorities, provided your skin tolerates it.1

If dryness and flaking are the whole problem, moisturizer comes first; an exfoliating acid is not compulsory. Moisturizers improve dry, flaky skin. Regular, long term use of alpha hydroxy acids can also reduce dryness in ageing skin, but adding an acid is a separate decision from meeting your skin's need for moisture.4

Can you compare glycolic and lactic acid percentages directly?

No. Equal percentages do not necessarily produce equal exfoliation. The acid type, concentration, pH and other ingredients all affect how much surface skin sheds. A bigger percentage is not a complete product description, however much space it gets on the bottle. For peels, the formula's buffering and how long the acid stays on the skin also affect depth.35

For consumer products, the Cosmetic Ingredient Review safety criteria include glycolic or lactic acid at 10 percent or less, a final pH of at least 3.5, and protection against increased sun sensitivity or directions for daily sun protection. These are safety criteria, not a reason to start dry skin at 10 percent. Check the complete directions rather than choosing by the percentage alone.3

How should you introduce an acid?

1. 1Read the product directions and warnings before applying either acid.
2. 2For glycolic acid, test a little on one area first and watch for irritation.
3. 3Start glycolic acid once or twice a week at night. Increase only if your skin tolerates it; nightly use is not a target you have to reach.
4. 4When introducing glycolic acid, avoid combining it with lactic acid, other exfoliants, retinol or vitamin C serums. Keeping fewer actives in the routine makes an irritation trigger easier to identify.

Both acids can increase sun sensitivity. Use broad spectrum SPF 30 or higher during the day, wear protective clothing and limit sun exposure. Continue sun protection for a week after stopping an AHA. Using glycolic acid at night does not remove the need for daytime protection.23

When is neither acid the right choice?

If you have rosacea, avoid both glycolic and lactic acid and stop exfoliating. A gentler acid is still an acid. Choose a fragrance free cream and gentle cleansing instead. If you struggle to find products that do not irritate your skin, ask a dermatologist for specific product suggestions.6

Stop using an acid if it causes burning, a rash, swelling or blistering. AHAs can cause these reactions, including chemical burns, particularly with products that produce greater exfoliation. Do not treat a stronger reaction as evidence that the product is working.3

Low concentration glycolic acid is generally considered safe in pregnancy, but check with your healthcare provider before using it while pregnant or breastfeeding. That advice is specific to glycolic acid, not a blanket clearance for every acid formula.2

Expect gradual changes rather than immediate correction of uneven tone. With glycolic acid products used at home, brighter skin or more even pigmentation can take several months of consistent use. Increasing exfoliation to hurry the result can instead cause dryness, irritation and increased sensitivity.2