Alpha hydroxy acids (AHAs) are a group of acids that occur naturally in fruits, sugar cane, and milk. Benefits of AHA include exfoliation, improved skin texture, and acne reduction.

Popular uses for AHAs include smoothing the skin, reducing dark spots or hyperpigmentation, and reducing the appearance of scars. But they are not always suitable for darker skin tones.

In this article, we will look at how AHAs work, their potential benefits, and how to use them safely.

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AHAs are a group of acids that naturally occur in certain foods. Many cosmetic treatments and products contain AHAs as a means of exfoliating the skin.

AHAs work by loosening the top layer of old skin cells by breaking down the gluey substance that keeps skin cells joined together. This encourages the skin to grow more cells, increasing cell turnover.

There are several types of AHA. Common examples of the AHAs dermatologists use include:

  • lactic acid, which is present in dairy and fermented vegetables
  • glycolic acid, which comes from sugarcane
  • malic acid, which is present in apples
  • citric acid, which is present in citrus fruits
  • tartaric acid, which is present in grapes

Lactic and glycolic acid are some of the most well-known AHAs. But all AHAs work in a similar way.

AHAs have a number of potential uses for the skin, including:

Gentle exfoliation

AHAs can be a good alternative to other methods of exfoliation, such as using abrasive brushes, scrubs, or face cloths. These methods of mechanical exfoliation can be harsh and cause irritation.

Exfoliation with a low-strength AHA may be more suitable for those with dry or sensitive skin.

Improving skin texture

Acid exfoliants, such as AHAs, can remove rough or flaky skin without causing irritation. As a result, they can reduce the appearance of dry skin, blemishes, and keratosis pilaris.

Reducing the visible signs of aging

Over time, and with exposure to the sun, the turnover of new skin cells slows down. This can increase the appearance of fine lines and wrinkles.

AHAs help to remove the top layer of dead skin cells, revealing fresh new cells underneath. With long-term use, AHAs may also increase collagen and elastin in the skin.

These substances give the skin structure and elasticity, but they naturally decrease with age. By using AHAs regularly, people may notice their skin looks plumper.

Reducing hyperpigmentation, melasma, and sun damage

Regular use of AHA products or peels may help to treat hyperpigmentation or dark marks on the skin, such as:

Dermatologists often use AHA peels for these purposes, as they can work on deeper layers of the skin than over-the-counter (OTC) products.

It is important to note that in darker skin, AHAs can cause dark spots and changes in skin tone. If this is a concern, speak with a dermatologist before using an AHA.

Reducing acne

AHAs may help some people to prevent acne by removing the dead skin cells that could block pores and cause pimples.

AHAs are one type of acid that can be useful in skin care. Beta hydroxy acids (BHAs) are a similar group of acids that also exfoliate the skin.

Examples of BHAs include:

  • beta hydroxybutanoic acid
  • tropic acid
  • trethocanic acid
  • salicylic acid, which can also appear on ingredient lists as salicylate, sodium salicylate, or willow bark extract

BHAs and AHAs have similarities, but some find BHAs more effective for oily and acne-prone skin. This is because they can:

  • improve skin texture
  • reduce the shedding of skin cells inside pores, reducing the chances of blockage
  • break down blackheads and whiteheads

Salicylic acid is the most common BHA in skin care products. As with AHAs, people can use salicylic acid in a variety of ways. People can also purchase products that combine AHAs and BHAs together.

Other types of acid in skin care products are not exfoliants. For example, hyaluronic acid (HA) is a humectant, and not an exfoliant. HA works by binding to water, keeping moisture in the skin.

People can use AHAs in a variety of ways. They can be present in:

  • cleansers
  • toners or tonics
  • face pads
  • serums
  • moisturizers

Some types of AHA products are wash-off, while others require a person to leave them on the skin. This and the AHA concentration can affect their potency.

Before choosing an AHA product or exfoliation method, the American Academy of Dermatology (AAD) recommends that people consider their skin type and the other products they already use.

If AHAs are already present in other products, or a person uses manual exfoliation, adding another exfoliant may be too much.

If people are unsure of which type of product to choose, they can consult a dermatologist for advice.

Using wash-off AHAs

To use a wash-off AHA, such as a cleanser, follow the instructions on the label. Alternatively, the AAD recommends:

  • applying the product using small, circular motions
  • leaving for 30 seconds
  • rinsing with lukewarm water
  • following with moisturizer

Using leave-on AHAs

For leave-on products, follow the instructions on the label. Some people prefer to apply leave-on products before sleep so that the products can work overnight.

AHA peels

AHA peels are prescription-strength treatments that can treat more pronounced skin concerns, such as rough texture or hyperpigmentation. They can be a less-intensive alternative to deep skin peels or laser resurfacing.

A dermatologist can carry out AHA peels in their office. They take around 15–20 minutes. First, a dermatologist will cleanse the skin, then apply the solution, which can range from 20–70% in strength.

The solution sits on the skin for several minutes before a person washes it off. People can use glycolic acid peels once every 1–2 weeks.

As AHAs are a type of acid, there are some safety precautions people should follow while using them.

Before use

As with other skin care products, it is important to take the following precautions before using an AHA:

  • test on a small area of skin before applying to a larger area
  • if the product causes irritation, stinging, or burning, rinse thoroughly and do not use it
  • if it does not cause a reaction, follow the product instructions for use on the face

People should not use AHAs if they have broken skin or sunburn. Do not use AHAs on infants or children.

After use

According to the Food and Drug Administration (FDA), AHAs can increase sensitivity to UV light. This is also true of BHAs.

For this reason, it is important to protect the skin from sunlight while using chemical exfoliants. The FDA recommends using products with:

  • an AHA concentration of 10% or less
  • a pH of 3.5 or above
  • SPF protection within the product

People can also apply sunscreen after using AHAs or BHAs. The AAD recommends that people use a daily sunscreen that is:

  • broad-spectrum
  • water resistant
  • SPF 30 or higher


Overuse is a potential risk when using AHA products. While most OTC products containing AHAs are gentle, if a person uses them too frequently, it can cause damage to the skin barrier.

Potential signs of over-exfoliation include:

  • irritation or burning
  • dryness or flakiness
  • blotchiness and uneven skin tone
  • increased sensitivity to other products

If signs of AHA overuse appear, stop using the product and seek advice from a dermatologist.

AHAs are a type of organic acid that people can use to exfoliate the skin. Over time, AHAs may help to improve skin texture, fade dark spots, and reduce the visible signs of aging.

AHAs can increase sensitivity to UV damage, so people will need to wear sunscreen every day while they are using them.