Your Ultimate Guide to AHAs

The anti-aging, dark spot fading, and acne healing benefits of AHAs have been known for centuries. Cleopatra used to bathe in sour milk to get the youthful benefits of lactic acid, which is a popular AHA.

Science tells us they work by a process of chemical exfoliation and new cell growth which leaves your skin looking younger, brighter, and with fewer signs of aging. AHAs fade hyperpigmentation, heal acne and rosacea, and get your skin glowing.

We’ll help you find the right pH and concentration so you can get to that sweet spot of results without irritation. This is your Ultimate Guide for understanding the what, why, and how of AHAs so you can get the best formula for your skin type, without irritation.  

For more, check out Anti Aging Facial Cream Ultimate Buying Guide and Best Natural Eye Creams for Anti-Aging

What are AHAs?

AHAs, or alpha-Hydroxy acids, have been around for centuries in one way or another. Cleopatra was known to literally bathe in sour milk because she knew it helped her skin look young and vibrant. Now, thankfully, we know it was the lactic acid in sour milk that kept her youthful beauty and we can just buy it, not subject ourselves to what must have been a very stinky bath.  

In scientific terms, AHAs are organic acids with one hydroxyl group attached to the alpha position of the acid. Glycolic acid, lactic acid, malic acid, tartaric acid, mandelic acid, hydroxybutyric acids, and citric acid are all types of AHAs. 

The most well researched of these are, by far, Glycolic and Lactic Acids. The other AHAs may also work wonders for your skin, but the data are pretty limited, so we’re focusing on the 2 most researched here. 

What Skin Problems Can AHAs Improve?


AHAs have been proven to improve: 

  • Signs of aging, especially from photodamage (UV damage)
  • Actinic damage, or actinic keratosis which is a precancerous skin damage from chronic UV exposure
  • Melasma, or “pregnancy mask” usually caused by hormone changes during pregnancy 
  • Hyperpigmentation (dark spots, sun spots) usually caused by UV damage or acne scars
  • Acne of all types
  • Rosacea, which causes redness and possibly pus-filled bumps on skin

How Do AHAs Work?

AHAs actually remove calcium ions from epidermal cell adhesions (in the stratum corneum) through a process called chelation, which is fancy for exfoliation. ‘Cell adhesions’ are  basically the glue that holds cells together, so weakening them has some amazing anti-aging benefits:

  • Cell adhesions become weaker which causes thinning and shedding of those old, dry, flaky cells bring out brighter, younger looking skin
  • New cells are produced faster and, it turns out, cell differentiation is slowed down making these new cells fresher and younger,  fading wrinkles and hyperpigmentation
  • Collagen (which gives skin its firm, smooth texture) and hyaluronic acid (which holds water and plumps up skin cells) increases in the dermis (where wrinkles live) and epidermis. This makes skin smoother and more radiant.
  • Melanin is dispersed which fades hyperpigmentations, like scars and melasma

Can AHAs Heal Acne?

The science says ‘yes.’

Acne is categorized into 2 main types, non-inflammatory and inflammatory. They have different causes, and are very different, but AHAs have been proven in numerous studies to improve all types of acne. Some just need a few more treatments than others.  

Non-Inflammatory Acne

Non-inflammatory acne crops up when pores (comedones) are clogged with sebum and dead skin cells. This is what we all know and love as whiteheads (closed comedones) and blackheads (open comedones).

Inflammatory Acne

Inflammatory acne erupts as acne papules (mild pimples), acne pustules (moderate to severe pimples), acne nodules (large, painful, inflamed lesions), and acne cysts (soft, large, fluid-filled bumps under skin). Many people get a sweet combo of these. 

Glycolic Peel for Acne

Using a Glycolic Acid peel, non-inflammatory acne was healed the fastest with an average of less than 6 applications. Inflammatory acne was gone after just a few more applications. 

Papulo-pustular acne needed an average of 6 applications and nodular-cystic needed  8-10 applications. But, in all cases, acne scars and cystic lesions were improved, skin texture was rejuvenated, pores shrunk, and volunteers had brighter healthier looking skin. Only a small percentage (5.6%) had any adverse effects. 

It’s important to mention BHAs when we talk about acne. They are another type of Hydroxy Acid and make a great partner to AHAs for people with oily or acne-prone skin.

BHAs, or beta-Hydroxy Acids, penetrate through the follicle to get deep into pores so they’re great at healing acne. The most popular BHA is salicylic acid, but a more natural alternative usually found in all natural acne products is called Willow Bark.


How Do I Buy the Best AHA?

Finding just the right AHA for your skin type and needs depends on a few factors. You should think about which active ingredients (usually lactic acid or glycolic acid) is better for your skin,, the pH of the solution, and the concentration, or strength, of it. 

Lactic Acid and Glycolic Acid

Lactic Acid and Glycolic Acid are, by far, the most popular and widely sold AHA “actives.” But the good news is, you may not have to choose between them. 

It turns out the most popular products are actually combinations of Lactic and Glycolic Acids. Some even thrown in a BHA (usually salicylic acid) and some skin soothing ingredients.

Lactic Acid and Glycolic Acid proved to be the most effective for improving wrinkles and acne than other AHAs like Citric Acid, Malic Acid, or Hydroxybutyric Acid. 

Glycolic Acid is made from sugarcane and has the smallest molecules of all the AHAs. This makes it penetrate pores more effectively than other AHAs. It’s great for acne, hyperpigmentation, anti-aging, and rosacea. It’s perfect for skin that is oily, combination, and normal. 

Lactic Acid is made from milk and is more gentle than Glycolic Acid. The risk of irritation is much less than Glycolic Acid so it’s better for dry, mature, or sensitive skin. 

Why Does pH Matter for AHAs?

The stratum corneum is part of the epidermis (the outermost layer of skin) and is what makes our skin impermeable to water but allows fats to absorb into the deeper layer of skin, the dermis. The dermis is where wrinkles live and for a skin care product to really get down there and work it’s magic, it needs to be able to penetrate the epidermis. They do this through finding the right pH. 

The stratum corneum is naturally oily (even if you don’t think you have oily skin) and AHAs need to be able to penetrate through the oil to soak into skin and work their magic. 

The lower the pH (closer to pH 0) the more skin is at risk for burning and irritation because the lower the pH of something, the more acidic it is. But if the pH of the AHA is higher than the stratum corneum, which is 4.5 to 5.0, it’s not going to be able to penetrate and get through to deeper layers of skin. 

The ideal pH of an AHA is 3.0 – 4.0. Not so acidic it will irritate most skin types but acidic enough to penetrate the stratum corneum.

What Concentration or Strength of AHA is Best?

Starting AHAs is kind of like starting retinol; you want all the benefits with the least amount of irritation. For most people, a concentration of 5-12% is a good starting point for over-the-counter strengths. Dermatologists can use a stronger AHAs in the office.  

A 5% Lactic Acid topical created positive changes in the epidermis but when volunteers used a 12% concentration, it actually influenced both the epidermis and dermis. This improves signs of aging, fades hyperpigmentation, heals acne, and improves rosacea.  

A combination of 8% Glycolic Acid and 8% Lactic Acid improved signs of aging like fine lines, wrinkles, blotchy red areas, sallow skin, and improved elasticity. 

Can I Pair AHAs with Anti Aging Skin Care Products?

anti aging

The effects of AHAs can actually be boosted by adding Nicotinamide (Vitamin B3), Vitamin C, and Vitamin E to your anti-aging skin care routine. 

After 21 days of using AHAs, Nicotinamide, Vitamin C and Vitamin E, 9 out of 10 volunteers in a group of 52 females age 30-55 years old reported improving fine lines and wrinkles, fading hyperpigmentation, healing red blotchy skin, improved sallow skin (yellowing), and overall smoother more youthful skin.

Another study concluded that an anti aging skin care routine with AHAs plus vitamins improved the biomechanical parameters of skin including fine lines and wrinkles, texture, and elasticity without causing additional irritation. This basically means the skin functions better and was healthier. 

Tips to Starting AHAs

  • Start small and work your way up to higher strengths
  • Start with pH 3-4 and strength of 5-12%
  • For dry, sensitive, or mature skin, try Lactic Acid first
  • BHAs work great for acne or oily skin but should be avoided with other types of skin to avoid irritation
  • Don’t be afraid to experiment with different products until you find the right one

To Sum It Up

AHAs can work wonders for your skin through exfoliation and cell renewal. Lactic and Glycolic Acids have been proven to heal acne and repair UV damage and signs of aging. The trick to getting started is finding a low enough strength and pH to avoid irritation but strong enough to get results.  With a little trial and error your skin will be noticeably brighter, more radiant, and younger looking.