What to Know About Lactic Acid for Skin Care

Medically Reviewed by Debra Jaliman, MD on February 29, 2024
3 min read

Lactic acid is an over-the-counter chemical exfoliant that comes from the fermentation of lactose — a carbohydrate found in milk. It's a popular ingredient in numerous skin care products nowadays. But its use is nothing new. It dates back to ancient Egypt. It's common knowledge that Cleopatra used to bathe in sour milk to keep her skin looking more youthful. ‌

‌Like glycolic and mandelic acids, lactic acid belongs to the alpha hydroxy acid (AHA) family. AHAs are water-soluble organic compounds that, in cosmetic formulations, offer unparalleled benefits for the skin. Lactic acid presents an additional advantage that other AHAs don't have. Besides its ability to significantly improve the skin's appearance, it helps keep it naturally hydrated.

Much like its more aggressive counterparts, lactic acid has many known perks. It increases cell turnover and helps eliminate accumulated dead skin cells on the epidermis — the top layer of the skin.

When using lactic acid in 12% concentrations, the skin gets firmer and thicker. As a result, there is an overall smoother appearance and fewer fine lines and deep wrinkles. These outcomes show that, in such high concentrations, lactic acid can permeate into the deeper layers of the skin. Lower concentrations of about 5% have no impact on the middle layer of the skin. Still, they have similar effects on a more superficial level.

‌After using lactic acid, you'll notice a brighter and smoother complexion. This AHA exfoliant helps treat moderate to severe hyperpigmentation, which happens when certain spots on your skin have more than the normal amount of melanin. It can fade out age spots and reduce the appearance of wrinkles and highly visible pores. Lactic acid is one of the mildest forms of AHA, so it's safe to use it on sensitive skin in the right concentrations. 

‌‌Lactic acid as an effective antimicrobial. Some research suggests that lactic acid and probiotic supplements can help with sensitive skin. By teaming up to fix certain inflammatory reactions, they can both give a microbial balance to the skin. While probiotics promote more in-depth regulation by balancing the gut, lactic acid works alongside them as a treatment for moderate skin conditions like psoriasis, eczema, and acne.

Lactic acid for acne. Skin with a tendency to get acne can be more sensitive to exfoliating therapies. Still, many doctors prescribe lactic acid chemical peels in low concentrations alongside antibiotic treatments. Using low concentrations has significantly improved the skin texture and reduced up to 90% of inflammatory lesions in people with acne in controlled clinical studies.

Even though it's a milder AHA exfoliant, you shouldn't use lactic acid too frequently. You risk over-exfoliating your skin and messing with its natural barrier. Consider using this effective skin resurfacing ingredient every other night unless your doctor says otherwise.

‌Be careful if you're using retinoids and aggressive scrubs. Avoid doing these treatments all at once, or you might see some irritation. In severe cases, you might cause post-inflammatory hyperpigmentation, which happens when the skin produces extra melanin as a natural response to stress. This type of hyperpigmentation can take a long time to fade out.

‌Using any chemical peel puts your skin at a greater risk of sun damage. Always wear an SPF 30+ whether you're outdoors or not. Reapply it every two hours when you're exposed to direct sunlight. Failing to protect your extra-vulnerable skin from UVA and UVB damage might increase your chances of getting skin cancer.

‌Follow the product's directions carefully. Some preventive measures you could take before applying lactic acid — or any other AHA exfoliant — are:

  • Making sure the lactic acid concentration is below 10%.
  • Looking for products with a pH of over 3.5.
  • Looking for products that warn about the potential effects of sun exposure after lactic acid use. 

Any chemical peel can cause adverse reactions. When trying out lactic acid for the first time, keep an eye out for: 

  • Redness
  • Swelling
  • Burning sensation
  • Severe itching
  • Noticeable peeling

If you notice any of these skin reactions, talk to your doctor as soon as possible. Also, take a break from exfoliants altogether. You don't want to cause any more stress to your already damaged skin.