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  • Alpha hydroxy acid (AHA) and beta hydroxy acid (BHA) are two of the most common ingredients in skincare products.
  • AHA and BHA are similar and are used for many of the same skin conditions, but BHA is oil-soluble, making it better for oily and combination skin.
  • Both AHA and BHA are found in over-the-counter and medical-grade skincare products, especially in chemical peels.

What is alpha and beta hydroxy acid?

Both AHA and BHA are used for their skin-perfecting power. But what do they do, and how do they differ from each other?

“Alpha hydroxy acids include glycolic acid, lactic acid, and other acids that originate from milk and fruit sugars,” says Dr. Robin Evans of Southern Connecticut Dermatology in Connecticut. “Beta hydroxy acids include salicylic acid.”

Both AHA and BHA are anti-inflammatory and are used for exfoliation and peeling, says Dr. Evans, and they can benefit people with stubborn skin issues.

“Both chemicals are often used as chemical peels in varying strengths, including over-the-counter strengths and spa- or physician-grade medical peels,” she says, adding that they can be used alone or in combination with other skincare ingredients.

Understanding the difference between these two acids is essential because it can help you determine which is best for your skin tone, skin type, and specific skin issues. To pick the right product for your skincare goals, you must know your ingredients.

What are the benefits of alpha hydroxy acid?

AHAs are naturally-occurring compounds derived from sugarcane, sour milk, and fruit. This category includes glycolic acid, lactic acid, malic acid, citric acid, mandelic acid, and tartaric acid. These acids promote cell turnover and collagen production and might also help to unclog pores and treat skin issues related to sun damage.

In general, alpha hydroxy acids are used for their anti-aging properties, as well as for exfoliation, pigmentary conditions like melasma, and as a treatment for comedonal acne, says Dr. Evans.

AHAs are good for treating dry skin, clogged pores, fine lines, wrinkles, sun spots, and melasma. They also act as chemical exfoliants, helping to break up dead skin cells and slough away dirt and debris in clogged pores, and encourage a natural shedding process for smoother skin.

Dr. Cynthia Bailey, of Dr. Bailey Skin Care, points out that AHA can actually promote the body’s ability to produce its own skin-boosting chemicals. “They stimulate your skin’s ability to make hyaluronic acid in the living skin layers,” she explains. “Hyaluronic acid is a natural skin component that creates a dewy youthful appearance to skin

What are the best alpha hydroxy acids?

“The best AHAs include glycolic and lactic acid,” says Dr. Bailey. “They are excellent keratolytics, meaning they break up dead skin cells to keep skin smooth and pores clear.” This helps to lighten skin hyperpigmentation that can come from sunspots and melasma.

Lactic acid is better than glycolic acid when it comes to hydrating, she adds.

If you want to try AHA for your skin, look for skincare products with between 5% and 15% AHA, and reserve higher concentrations for your next chemical peel.

RELATED: Types of Chemical Peels — Before & After, Side Effects, Cost, and Aftercare

What are the benefits of beta hydroxy acid?

BHA is a naturally occurring chemical derived from foods and plants, including willow bark. Generally, BHA is recommended for people with acne-prone skin. BHA is similar to AHA but BHA is oil-soluble, and AHA is water-soluble. This means that a BHA product might be better for oily skin. Salicylic acid, the most common BHA, is the main component in aspirin.

BHA is also “a keratolytic, but is less effective than AHAs at breaking dead skin cells apart,” says Dr. Bailey. “It is better, however, at seeping into oil. This means it is really great for clearing out oily, clogged pores.”

Not only is BHA more effective for treating acne and clogged pores in people with oily skin, it also might help clear up excess oil. Most natural exfoliators can be irritating for people with sensitive skin, but BHA has skin-soothing properties, so if you struggle with blemishes or have more sensitive skin, stick to BHA.

What are the best beta hydroxy acids?

There are BHAs other than salicylic acid that are used in skincare products. However, we recommend sticking to products that contain salicylic acid, as it’s one of the BHAs with the most research behind it. You will most likely have better results and fewer side effects.

What are the risks of AHA and BHA?

Both AHA and BHA are off-limits for people with certain skin types, say the dermatologists.

People with darker skin, sensitive skin, or rosacea should be very cautious when using either product, says Dr. Evans.

Those with sensitive skin might experience irritation, redness, or flaky skin after using either BHA or AHA, Dr. Baily adds.

Allergies are also a concern, so you should always test a small area of your skin or consult with a dermatologist before using a product with AHA or BHA.

“Some people are allergic to salicylic acid, but allergies to AHAs are almost non-existent,” says Dr. Bailey. “That said, both BHA and AHAs are irritating.”

In addition, Dr. Evans suggests giving an antiviral prophylaxis for “individuals with a history of herpes simplex cold sores,” as AHA and BHA “peels can trigger a herpes flare.”

Which one is best for you?

If you don’t suffer from sensitive skin, there’s a good chance that you would benefit from both of these acids in your skincare regimen. Use AHA for anti-aging and deep exfoliation, and BHA for acne and oily skin.

Remember to always talk with a board-certified dermatologist for one-on-one advice and tailored skincare recommendations.

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