Alpha hydroxy acid (AHA): benefits, uses and side effects
AHAs may help smooth out and brighten complexions. Let's take a closer look at what they do and what to know.
En este artículo:
What are alpha hydroxy acids?
AHAs are types of organic acids naturally present in sugarcane, fruit and sour milk. Yes, that means, glycolic acid, citric acid and lactic acid - and they're in many cosmetics that help some people support their complexion. These potentially helpful acids come in many different forms, including chemical peels, gels, lotions and serums.
Studies suggest that these acids stimulate cell renewal and can contribute to a reduction in the appearance of wrinkles and fine lines.
Types of alpha hydroxy acids
Citric acid
Naturally found in citric fruits and juices, citric acid is used in personal care products to adjust the acidity of the skin, as well as to promote skin turnover and stimulate cell growth.
Glycolic acid
Glycolic acid, the smallest of the AHAs, has the ability to penetrate the skin. It may reduce the appearance of wrinkles, acne scarring and hyperpigmentation. Glycolic acid often comes in the form of a chemical peel in skin care.
Lactic acid
Lactic acid is used to help smooth and firm up the skin. Studies show that it can also improve the appearance of wrinkles and fine lines, while also potentially firming the skin.
Malic acid
Malic acid adjusts pH levels in the skin, and it’s also used in exfoliants.
Mandelic acid
A natural derivative of bitter almonds, mandelic acid gently exfoliates the skin when applied. It has antibacterial effects and can be used to reduce inflammation caused by acne and rosacea.
What do alpha hydroxy acids do?
AHAs exfoliate dead skin cells from the skin's surface. They are frequently found in skin peels that may help reduce the appearance of acne, scars and possibly hyperpigmentation. These acids may also help improve the appearance of wrinkles as they help thicken the skin.
AHAs can also increase the skin’s photosensitivity, which means that precautions need to be taken. Avoid direct sunlight and regularly apply a protector solar with a sun protection factor (SPF) of 30 or higher.
How to use alpha hydroxy acids
The best way to introduce AHAs into a skin care routine is to speak with a dermatologist or other health care provider before starting. They can advise on the optimal ways to use them.
Always follow the instructions on the product label. But there are some general ways to approach using AHAs.
When exfoliating, products containing AHAs should generally be applied to clean skin using small circular motions. Wash off with lukewarm - but not hot - water and moisturize immediately after to keep exfoliated skin hydrated.
How often to exfoliate with an AHA depends on skin type and sensitivity. Consult with a health care provider first. Consider experimenting with a small amount of an AHA and see how the skin reacts.
For itchy or overly dry skin, immediately stop using the AHA product and contact a health care provider.
Use of AHAs can increase sensitivity of the skin to ultraviolet (UV) light. When using products containing AHA, avoid spending time in direct sunlight and regularly apply sunscreen.
Alpha hydroxy acids side effects
Always refer to the product label for directions and safety information. Common side effects after using AHA products include burning, itchiness, redness, skin sensitivity and swelling. If experiencing adverse effects from using a product with AHA, stop using the product and contact a health care provider.
Este contenido es solo para fines informativos y no constituye un asesoramiento médico. Consult your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.
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FOR AHAS ARE TYPES OF ORGANIC ACIDS PRESENT IN SUGARCANE, FRUIT AND SOUR MILK SOURCE: Tang SC, Yang JH. Dual effects of alpha-hydroxy acids on the skin. Molecules. 2018;23(4):863.
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FOR THESE ACIDS STIMULATE CELL RENEWAL AND CAN CONTRIBUTE TO A REDUCTION IN THE APPEARANCE OF WRINKLES AND FINE LINES SOURCE: Tran D, Townley JP, Barnes TM, Greive KA. An antiaging skin care system containing alpha hydroxy acids and vitamins improves the biomechanical parameters of facial skin. Clinical, Cosmetic and Investigational Dermatology. 2014;8:9-17.
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FOR CITRIC ACID SOURCE: Skin Deep. Citric acid. Environmental Working Group. Accessed September 16, 2025.
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FOR GLYCOLIC ACID SOURCE: Narda M, Trullas C, Brown A, et al. Glycolic acid adjusted to pH 4 stimulates collagen production and epidermal renewal without affecting levels of proinflammatory TNF-alpha in human skin explants. Journal of Cosmetic Dermatology. 2021;20(4):1272-1278.
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FOR GLYCOLIC OFTEN COMES IN THE FORM OF A CHEMICAL PEEL SOURCE: Sharad J. Glycolic acid peel therapy — a current review. Clinical, Cosmetic and Investigational Dermatology. 2013;6:281-288.
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FOR LACTIC ACID IS USED TO HELP SMOOTH AND FIRM UP THE SKIN SOURCE: Smith WP. Epidermal and dermal effects of topical lactic acid. Journal of the American Academy of Dermatology. 1996;35(3):388-391.
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FOR MALIC ACID ADJUSTS PH LEVELS IN THE SKIN SOURCE: Lee B, Heo J, Hong S, et al. Malic acid as a component of α-hydroxy acids: effect on 2,4-dinitrochlorobenzene-induced inflammation in atopic dermatitis-like skin lesions in vitro and in vivo. Immunopharmacology and Immunotoxicology. 2019;41(6):614-621.
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FOR MANDELIC ACID SOURCE: Gentili G, Perugini P, Bugliaro S, et al. Efficacy and safety of a new peeling formulated with a pool of PHAs for the treatment of all skin types, even sensitive. Journal of Cosmetic Dermatology. 2022;22(2):517-528.
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FOR AHAS EXFOLIATE DEAD SKIN CELLS FROM THE SKIN'S SURFACE SOURCE: U.S. Food and Drug Administration. Alpha hydroxy acids. Updated November 22, 2022.
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FOR HELP REDUCE THE APPEARANCE OF ACNE, SCARS AND POSSIBLY HYPERPIGMENTATION SOURCE: Tang SC, Yang JH. Dual effects of alpha-hydroxy acids on the skin. Molecules. 2018;23(4):863.
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FOR SUNSCREEN WITH A SUN PROTECTION FACTOR (SPF) OF 30 OR HIGHER SOURCE: American Academy of Dermatology. Sunscreen FAQs. Updated February 11, 2025.
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FOR WHEN EXFOLIATING SOURCE: American Academy of Dermatology Association. How to safely exfoliate at home. Consultado el 16 de septiembre de 2025.
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FOR HOW OFTEN TO EXFOLIATE SOURCE: American Academy of Dermatology Association. How to safely exfoliate at home. Consultado el 13 de agosto de 2025.
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FOR ITCHY OR OVERLY DRY SKIN SOURCE. Ludmann P. Dermatologists' top tips for relieving dry skin. American Academy of Dermatology Association. Actualización: 16 de mayo de 2024.
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FOR CAN INCREASE SENSITIVITY OF THE SKIN TO ULTRAVIOLET (UV) LIGHT SOURCE: U.S. Food and Drug Administration. Alpha hydroxy acids. Updated November 22, 2022.
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FOR COMMON SIDE EFFECTS AFTER USING AHA PRODUCTS SOURCE: Tang SC, Yang JH. Dual effects of alpha-hydroxy acids on the skin. Molecules. 2018;23(4):863.