Also known as: AHA, alpha hydroxy acid; sodium lactate is a related humectant salt
What Is Lactic Acid (AHA)?
Lactic acid is an alpha hydroxy acid historically associated with soured milk, though cosmetic lactic acid is now usually produced by fermenting plant sugars. Its molecule is larger than that of glycolic acid, so it penetrates more slowly. In practice, that usually means a gentler exfoliation with less stinging.
What makes lactic acid unusual is its second job. Lactate is part of the skin's natural moisturizing factor, the blend of compounds that help the outer layer hold water. At lower concentrations, lactic acid and its salt, sodium lactate, act mainly as humectants. At higher concentrations and lower pH, they shift toward exfoliation. That combination makes lactic acid a sensible choice for dry skin that is also rough and flaky.
Regular use helps loosen dead cells, smooth texture and brighten a dull complexion, and over time it can help with mild uneven tone. It works in a similar way to another humectant-exfoliant, urea, which is also found in products for rough, dry skin.
Lactic Acid (AHA) Benefits for Skin
- Exfoliates gently to smooth rough, flaky patches.
- Helps skin attract and hold moisture.
- Brightens a dull, uneven-looking complexion.
- Usually better tolerated than glycolic acid.
- Helps soften the look of mild discoloration over time.
How to Use Lactic Acid (AHA)
Use a lactic acid serum, toner or overnight treatment two or three evenings a week on clean skin, followed by a nourishing moisturizer. If your skin tolerates it well, you can increase frequency. In a routine for dry skin, lactic acid pairs naturally with hydrators like hyaluronic acid and barrier-supporting ceramides.
As with every AHA, wear broad-spectrum sunscreen daily, and keep lactic acid and retinoids on separate nights unless a dermatologist advises otherwise. Body lotions with lactic acid are also popular for rough elbows, knees and heels, where skin is thicker and usually tolerates it well.
Side Effects & Precautions
Lactic acid can still cause tingling, redness or peeling, particularly at higher strengths or on sensitive skin. Introduce it slowly and stop if irritation lasts beyond a few minutes after application.
AHAs increase sun sensitivity. Skipping sunscreen while using lactic acid can lead to sunburn and may worsen the very discoloration you are trying to fade.
Use caution when combining
- Retinoids on the same night.
- Other exfoliating acids or scrubs in the same routine.
Frequently Asked Questions
Is lactic acid better than glycolic acid?
Not better, but different. Lactic acid is gentler and adds hydration, while glycolic acid usually works faster but irritates more easily. Dry or mildly sensitive skin often does better with lactic acid.
Can lactic acid help with keratosis pilaris on the body?
Many body lotions for rough, bumpy skin use lactic acid or ammonium lactate to soften texture. If bumps are widespread or inflamed, a dermatologist can confirm what they are and suggest options.
Is lactic acid vegan?
In most modern cosmetics, yes, because it is usually made by fermenting plant sugars rather than derived from dairy. If this matters to you, check with the product's manufacturer.