Acid Trip: The Scoop on Chemical Exfoliants

Acids have been a huge trend in skincare in the last decade, but it feels like a new one is introduced every couple of years.

It can feel overwhelming with so many options. Some tackle oily skin, some address large pores, and some simply slough off the outermost layer of dead skin to give you that glow.

I tend to err on the side of caution versus going straight for an ingredient that is aggressive, which might be damaging to some skin types. I advise that you do the same. Take caution and always do a test patch to see how your skin reacts. The number of times you use any acid during the week depends on which acid you're using and your skin type. That's another post for another time!

There are so many types of acids. I'll do my best to break down the most popular ones and what skin types they are best for. As a dry, acne-prone, sensitive skin type myself, I've had my fair share of trial and error. Follow me down my acid trip of a rabbit hole.

Alpha Hydroxy Acids

Alpha Hydroxy Acids (AHA’s) are generally more gentle so most people are fine using these. They are especially best for those with dry skin or sensitive skin since these acids dissolve the binder between dead skin cells without breaking down the topmost oil barrier that keeps our skin protected and hydrated. AHA’s do not go as deep into the skin as Beta Hydroxy Acids (more on that later) and therefore are not as aggressive as an exfoliant.

AHA’s are also the best acid to use on melanated skin. People of color tend to scar more easily. When the cells rush to repair the damaged skin, it brings more melanin, usually resulting in more obvious scars. AHA’s are a gentle way to fade scars over time without the risk of causing more scarring.

Glycolic Acid

Glycolic acid comes from sugar cane and is stronger than lactic acid. Its molecules are smaller and will go deeper into the skin, but still do not damage the outermost oil barrier. Glycolic acid can be used for all skin types. It may still be too aggressive of acid for people with very sensitive skin.

Lactic Acid

Lactic acid comes from dairy and is a gentler acid than glycolic acid. The molecules aren’t as small so they don’t go as deep into the skin. It may not be a strong enough exfoliator for some, but if someone scars easily, this may be a better option to start with so there are fewer chances of discoloration.

Lactic acid is best for melanated, sensitive, dry skin, and those new to adding acids to their skincare routine. It is also the best acid for dry skin overall since it is a humectant–meaning it draws moisture into the skin and helps add hydration.

Malic Acid

Malic acid is milder than lactic acid and is usually not strong enough to be a stand-alone ingredient. It’s found in unripe fruit, mostly in apples. It is not well-known but a rising star. It is also a humectant helping boost skin's hydration.

Tartaric Acid

Tartaric acid is also a lesser-known acid, very mild, and again not usually used on its own. It usually is taken from grapes.

Citric Acid

Citric acid has been used in food products as a preservative for years and is slowly becoming more popular in skincare products as an exfoliant. Although most believe that all citric acid comes from citrus fruits, most commercially produced citric acid comes from fermented sugars from the mold that grows on corn. I know, what?

Beta Hydroxy Acids

I’m not sure why I made that plural because I only know of one BHA. Though scientifically it’s not even a BHA, it’s just considered that in the cosmetics and skincare world.

Salicylic Acid

Salicylic acid was originally taken from the bark of trees like white willow and has been used as far back as the 1st century AD. That's right, the 1st century. It has been used for centuries to treat skin ailments. We still use it to this day and it is one of the most popular chemical exfoliants.

It works by reducing redness, reducing inflammation, and also fights bacteria. Unlike AHA's that are more gentle, salicylic acid goes deeper to clear out clogged pores. This could be great for those with acne-prone oily skin but is not the best option for acne-prone dry and sensitive skin. For these skin types, it tends to be too drying and causes more damage than good. If you have dry skin and cystic acne, it probably will not go deep enough and could make the acne worse, drying out the surface of the skin and damaging the microbiome layer. (I speak from direct experience with this one, oops!)

Other Acids

Azelaic Acid

Azelaic acid is not an AHA or BHA, it is a dicarboxylic acid (try saying that ten times fast). It is mostly found in wheat and rye. It works by reducing inflammation and redness and is best used to treat rosacea and acne-prone oily skin. It also inhibits discoloration so can be a good option for people of color that want to reduce the appearance of scars. It can irritate sensitive and dry skin types.

Phytic Acid

Phytic Acid is not an AHA or BHA, it’s actually an antioxidant. It actively blocks the absorption of calcium, zinc, and iron. Calcium especially is known to cause sebum to clog pores. Phytics acid helps reduce breakouts, and blackheads, and shrinks pores, so it’s best for someone with oily skin.

Poly Hydroxy Acid

Poly hydroxy acids are cousins to AHA's. The molecules are larger so they do not penetrate the skin as deeply, leaving fewer chances for a bad reaction. This is great for sensitive skin and safe to use on melanated skin.

Acids for Skin-Types and Skin Tones

Maybe even after reading all of this, you're left thinking, "how the hell do I narrow that down?" Well, I hope the lists below can help with that.

Find where your skin has cross-over. Are you melanated and dry? Glycolic or lactic acid may be best for you. Are you oily, acne-prone, and sensitive? Maybe start with glycolic. Are you lighter-toned, oily, have large pores, and are not too sensitive to ingredients? Salicylic!