AHA or BHA: what the names do and do not tell you

Chemical exfoliation uses active compounds, such as alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs), to dissolve dead skin cells from the surface layer of the skin 1. A common misconception in skincare routines is that having dry skin automatically mandates an AHA, while oily skin automatically requires a BHA. In practice, choosing an acid based solely on a binary oily-versus-dry classification oversimplifies chemical exfoliation and overlooks critical factors such as product concentration, formula pH, underlying skin conditions, concurrent active treatments, and pigmentary risks 123.

Names and examples: understanding AHA and BHA ingredient families

The names "alpha hydroxy acid" and "beta hydroxy acid" refer to the chemical structure of two distinct ingredient families, but product packaging can obscure what these names actually represent 45.

Alpha hydroxy acids are ingredients included in cosmetic formulations to smooth surface wrinkles, refine skin texture, unblock pores, and improve general skin appearance 6. The most common AHAs found in retail cosmetic products are glycolic acid and lactic acid, alongside citric acid, hydroxycaprylic acid, and hydroxycapric acid 4.

By contrast, FDA identifies salicylic acid as the BHA most commonly used in cosmetics, alongside less common ingredients such as beta hydroxybutanoic acid, tropic acid, and trethocanic acid 5. From a strict chemist's perspective, salicylic acid is not a true beta hydroxy acid; however, cosmetic nomenclature widely categorises and markets it as a BHA 7. Cosmetic manufacturers frequently market BHAs with claims that they improve skin texture and fine lines with less occasional irritation than AHAs 8. Nevertheless, both families function fundamentally as chemical exfoliants that loosen surface skin cells 18.

Formula and pH: how concentration and acidity shape performance

The extent of chemical exfoliation is not dictated by the name on the bottle alone; it depends on the acid concentration, the product's pH, and the overall formulation 3.

For alpha hydroxy acids, the Cosmetic Ingredient Review (CIR) Expert Panel concluded that its industry review considered glycolic/lactic cosmetic products safe under the following conditions; these are not a personal suitability certificate or Zambian legal limits 9:

• The AHA concentration is 10 per cent or less 9.
• The final product maintains a pH of 3.5 or greater 9.
• The packaging directs daily sun protection or the formula is designed to mitigate increased sun sensitivity 9.

FDA says the extent of exfoliation depends on the AHA type/concentration, pH and other ingredients 3. A front-label family name therefore does not determine the effect of every finished product. Similarly, FDA reports CIR’s tentative conclusion about salicylic-acid cosmetics formulated to avoid irritation and sun sensitivity 5. Regardless of whether a formula contains an AHA or a BHA, applying higher concentrations or highly acidic formulations to dry, compromised, or sensitive skin can cause severe irritation 125.

Evidence by concern: does skin type dictate your acid selection?

While skin type provides a general baseline—where dry skin is flaky, rough, or itchy and oily skin appears shiny or greasy—it does not automatically dictate your acid choice 1.

For example, individuals with dry or sensitive skin are often advised to avoid aggressive mechanical scrubs and may prefer a mild chemical exfoliator or just a soft washcloth 2. However, if that mild chemical exfoliant is formulated at an inappropriate pH or combined with irritating active ingredients, it can worsen dryness regardless of whether it is labelled as an AHA or a BHA 23.

Furthermore, skin concerns often overlap. Someone with dry skin may experience clogged pores, while someone with oily skin may suffer from severe surface dehydration or sensitivity 1. In both cases, selecting an exfoliant requires evaluating the specific skin concern rather than relying on a rigid rule:

• Hyperpigmentation and uneven tone: Both AHAs (such as glycolic acid) and other topical actives (such as azelaic acid, kojic acid, retinoids, or vitamin C) are recognised for fading dark spots 11.
• Acne-prone or oily skin: While mild chemical exfoliants can assist with pore clearance, using strong chemical treatments on acne-prone or dry skin that is already inflamed can exacerbate dryness or trigger further breakouts 2.
• Sun sensitivity and photo-ageing: Research demonstrates that topical AHA use increases skin sensitivity to ultraviolet (UV) radiation 12. The FDA’s described study results are specific research findings, not an 18-per-cent prediction for every person or AHA bottle. To guard against sun damage, the FDA recommends a Sunburn Alert on AHA cosmetics advising consumers to use sunscreen, wear protective clothing, and limit sun exposure during use and for one week afterwards 13. Daily sun protection is likewise advised when using BHA products 514.

Irritation, pigment, and barrier risks: avoiding over-exfoliation

Over-exfoliation and inappropriate product pairing pose significant risks to the skin barrier. Dermatologists highlight several critical precautions before introducing chemical acids:

1. Pre-existing skincare actives: If your routine already includes prescription retinoid creams, over-the-counter retinol, or benzoyl peroxide, introducing chemical exfoliants can worsen dry skin, trigger peeling, or cause acne flare-ups 215. Retinoids themselves increase skin sensitivity and require slow introduction and consistent daytime sun protection 1516.
2. Darker skin tones and hyperpigmentation: Caution is essential for individuals with darker skin tones 2. Aggressive mechanical scrubbing or strong chemical exfoliation can trigger post-inflammatory hyperpigmentation, leaving behind stubborn dark spots or patches 217. In skin of colour, any severe product irritation can trigger melanin overproduction 1618.
3. Rosacea and reactive conditions: If you have rosacea or skin prone to severe redness and stinging, dermatologists specifically advise avoiding glycolic acid and lactic acid 19. In fact, if active rosacea is present, dermatologists recommend stopping exfoliation entirely as part of gentle care 20.
4. Sunscreen compatibility: Daily broad-spectrum sunscreen offering SPF 30 or higher is recommended by AAD when using chemical exfoliants 131421. For individuals addressing hyperpigmentation or dark spots, using a tinted sunscreen containing iron oxide provides essential protection against visible light 222324.

When professional advice helps: navigating complex skin needs

Because chemical acids interact dynamically with your skin type, existing routine, and environmental exposure, a trial-and-error approach can lead to irritation or discolouration 225. FDA advises trying a BHA cosmetic on a small area before a large one, following its label without exceeding the recommended applications, avoiding use on infants/children and using sun protection. For irritation or prolonged stinging, stop and consult a physician 14. A small-area product check is not specialist medical patch testing, and it does not override the actual label.

If you are uncertain about your exact skin type, experience persistent stinging or redness, or wish to safely treat stubborn hyperpigmentation or acne, see a board-certified dermatologist 1427. A dermatologist can thoroughly evaluate your skin barrier and recommend an individualised, evidence-based routine 27.

For residents seeking cosmetic applications, beauty grooming, or studio treatments in Lilayi, Lusaka, Luté Beauty Studio provides client care and appointment bookings 28. However, for clinical diagnosis, prescription management, or specialised dermatological assessment of acid exfoliants, professional guidance from a qualified medical dermatologist remains essential 2728.

Practical asset: Acid-label comparison and user guide

This practical asset provides a structured comparison of AHA and BHA ingredient labels, intended cosmetic uses, concentration guidelines, and actual label questions and source-scoped precautions.