Lactic Acid: Comedogenic Rating & Safety Profile
Also known as: Milk Acid · AHA
A gentle AHA derived from fermented sugars or milk. Larger molecule than glycolic acid, making it less irritating but still effective.
Quick facts about Lactic Acid
Safe
0 = won't clog pores · 5 = highly pore-clogging
Low Risk
0 = inert · 5 = often irritating
Acids
Generally considered safe
Typically yes
Milk Acid, AHA
Quick verdict
Lactic Acid is a acid with a safe comedogenic profile (0/5) and low risk irritancy (2/5). A gentle AHA derived from fermented sugars or milk. Larger molecule than glycolic acid, making it less irritating but still effective.
What is Lactic Acid?
Lactic acid is an alpha hydroxy acid (AHA) originally derived from milk fermentation but now produced cosmetically through the fermentation of plant sugars (so most modern cosmetic lactic acid is vegan). It is a larger molecule than glycolic acid, which means it penetrates more slowly and gently — making it the ideal AHA for sensitive skin or anyone new to chemical exfoliation. Unlike glycolic acid, lactic acid is also a humectant, drawing water into the skin while it exfoliates.
Comedogenic Rating: What 0/5 Means for Your Skin
Lactic acid is rated 0/5 comedogenic. Like other AHAs, it accelerates surface cell turnover and prevents the build-up of dead cells that contribute to dullness and surface congestion.
Benefits for skin
- Gentlest AHA — best entry point for chemical exfoliation
- Hydrating as well as exfoliating
- Brightens tone and softens texture
- Builds skin barrier when used at low percentages
Potential side effects & who should avoid it
Irritancy rating is 1–2/5 — gentler than glycolic acid. Mild stinging and dryness in the first 1–2 weeks are normal. Sun sensitivity increases, so daily SPF 30+ is essential. Very high concentrations (10%+) can over-exfoliate sensitive skin.
Best for
- Sensitive
- Dry
- Mature
- Normal
Avoid if
- Active eczema
- Sunburn
How to use Lactic Acid safely
Start with 5% leave-on, 2–3 nights per week. Build to 4–5 nights per week over 6 weeks. SPF the next morning. Don't combine with retinol on the same evening for the first month.
Commonly found in
Lactic acid is in toners, serums, masks, body lotions for keratosis pilaris and gentle chemical peels.
Found Lactic Acid in your skincare?
Paste the full ingredient list into our INCI Analyser to see how this ingredient interacts with everything else in the formula.
Frequently asked questions
Is lactic acid comedogenic?
Is lactic acid safe for sensitive or acne-prone skin?
Can I use lactic acid every day?
Is lactic acid better than glycolic acid?
Other acids to know
Retinol
A Vitamin A derivative that accelerates cell turnover, boosts collagen and is the gold-standard ingredient for reducing wrinkles and acne.
Salicylic Acid
An oil-soluble exfoliant that penetrates into pores to dissolve sebum, dead skin and the plugs that cause blackheads and acne.
Glycolic Acid
The smallest AHA molecule, derived from sugarcane. It exfoliates the surface of the skin to reveal smoother, brighter, more even-toned skin.
Benzoyl Peroxide
An over-the-counter antibacterial that kills C. acnes bacteria and reduces inflammation. Often the first-line treatment for inflammatory acne.
Want the full picture on pore-clogging ingredients? Read our complete guide to comedogenic ingredients for the dermatology research behind the 0–5 scale and the full list of high-risk ingredients to avoid.
Written by ScanSkinAI Cosmetic Science Team · Last updated June 2026
This information is for educational purposes only. Always patch-test new products and consult a dermatologist if you have specific skin concerns.