With so many chemical exfoliants to choose from, it can be hard to figure out which one is best for you or even what each one does. What’s the difference between lactic acid and glycolic acid? Is lactic acid or glycolic acid better?
Chemical exfoliants make your skin shed quicker than it would on its own. They do this by breaking up the bonds that hold your dead skin cells together, which makes it easier for them to come off the surface of your skin. Chemical exfoliants come in three main types: alpha-hydroxy acids (AHAs), beta-hydroxy acids (BHAs), and polyhydroxy acids (PHAs).
Chemical Exfoliation
| Lactic Acid | Glycolic Acid |
|---|---|
| It’s an AHA acid. Comes from milk. | It’s an AHA acid. Comes from sugar cane. |
Lactic acid is an AHA that comes from milk’s sugars (lactose). It is usually less irritating than glycolic acid, and because it moisturizes, it may be better for people with dry skin. AHAs, like lactic acid, help get rid of dead skin cells, which is their main benefit.
The sugar cane plant makes glycolic acid, which is an AHA. Glycolic acid exfoliates skin by removing the calcium ions from the bonds that hold your dead skin cells together. This makes the bonds weaker and makes exfoliation possible.
Main Benefits
| Lactic Acid | Glycolic Acid |
|---|---|
| Improves fine lines and wrinkles. Improves skin texture. Brightens skin. Reduces enlarged pores. | Improves skin texture. Reduces hyperpigmentation. Brightens skin. Improves acne. Boosts collagen production. Improves fine lines and wrinkles. Reduces the appearance of enlarged pores. |
Lactic acid also helps to improve fine lines and wrinkles, skin texture, brighten it, and reduce enlarged pores.
While glycolic acid benefits include the ability to improve skin texture, reduce hyperpigmentation, brighten the skin, improve acne, boost collagen production, improve fine lines and wrinkles, and reduce the appearance of enlarged pores.
Molecular Weight
| Lactic Acid | Glycolic Acid |
|---|---|
| Molecular weight (90) | Molecular weight (72) |
One of the most important differences between lactic acid and glycolic acid is that their molecular weights are different. Glycolic acid has a lower molecular weight (72) than lactic acid (90), so it is easier for it to get into your skin, even the deeper layers (your dermis). This means that, in general, glycolic acid is more effective than lactic acid.
Clinical Study
| Lactic Acid | Glycolic Acid |
|---|---|
| 71% | 76% |
One clinical study compared 8% lactic acid creams to 8% glycolic acid creams and found that 71% of people who used the lactic acid cream and 76% of people who used the glycolic acid cream saw an overall improvement in their sun-damaged skin. This suggests that both creams were similarly effective. Both creams reduced sun damage and made the skin less yellow, but lactic acid also made the skin less mottled and less rough.
How To Use
| Lactic Acid | Glycolic Acid |
|---|---|
| Apply on dry skin. Apply for nighttime. Up to 3 times/week. | Apply on dry skin. Apply for nighttime. Up to 3 times/week. |
Both lactic acid and glycolic acid should be applied to dry skin no more than three times a week to avoid irritation. Also, it’s better to use acids at night, since your skin’s natural exfoliation process is stronger at night.
Acids work best on dry skin, but you can also put them on top of a moisturizer if you want. This is called “buffering” because it makes it take longer for the acids to get into your skin, which can help calm irritation.
Concentrations
| Lactic Acid | Glycolic Acid |
|---|---|
| It’s an AHA acid. Comes from milk. | It’s an AHA acid. Comes from sugar cane. |
Lactic acid and glycolic acid are safe to use in over-the-counter products with a concentration of up to 10% and a pH of 3.5, and in professional peels with a concentration of up to 30% and a pH of 3.0. But if you’ve never used acids before, start with lower concentrations (like 5%) and build up the strength as your skin adjusts. This can help stop irritation and make skin purging less severe.
In Summary
Lactic acid and glycolic acid are both AHAs that work the same way and give your skin similar benefits. When you compare lactic acid to glycolic acid side by side, lactic acid is usually more tolerated and has fewer side effects (redness, irritation, etc.).
So, lactic acid is probably a better choice for people with dry or sensitive skin. But if you want something that has been tried and tested, glycolic acid is the better choice. For recommended products and download this comparison PDF, click on the link in the description.