What does the name mean?
The "poly" part refers to multiple hydroxyl groups, parts of the molecule containing oxygen and hydrogen. PHAs have two or more of these groups. They belong to the broader hydroxy acid family used in skincare, alongside AHAs. PHA names a category rather than one specific formula, so three letters have not finished your shopping for you.2
What do PHAs do for skin?
- PHAs provide mild exfoliation, helping remove dead skin cells for a smoother surface and a more radiant appearance.
- PHAs act as humectants, meaning they draw moisture into skin. Their role is not limited to removing surface cells.
- PHAs offer antioxidant benefits, helping counter free radicals and oxidative stress.
Gluconolactone is one PHA name you can look for on an ingredient list. Eucerin uses gluconolactone for its exfoliating, hydrating and antioxidant properties. Lactobionic acid is another name associated with the PHA and related bionic acid family.12
How is PHA different from AHA?
| Feature | PHA | AHA |
|---|---|---|
| Full name | Polyhydroxy acid | Alpha hydroxy acid |
| Examples | Gluconolactone | Glycolic acid and lactic acid |
| Exfoliation | Mild exfoliation with generally less irritation | Encourages shedding by loosening the substances holding surface cells together |
| Hydration | Draws moisture into skin | Hydroxy acid preparations can also act as moisturizers |
PHAs are worth considering if you want exfoliation but find other acids irritating. They offer similar benefits to AHAs with less irritation and can suit sensitive or reactive skin, including skin prone to rosacea. Less irritating does not mean irritation is impossible. Choose by the job you want the product to do, because an acronym is a poor substitute for a shopping list.12
Does PHA tell you how to use the product?
No. The ingredient category alone does not give you an application schedule, strength or waiting time for results. Follow the directions for the particular product rather than borrowing a glycolic acid peel routine. Hydroxy acid products differ in concentration and formulation, and stronger peels are a different use from everyday skincare. Sun protection remains part of an exfoliating skincare routine.23
Where this answer comes from
- 1PHAint.eucerin.com
- 2Applications of hydroxy acids: classification, mechanisms, and photoactivitypmc.ncbi.nlm.nih.gov
- 3Alpha hydroxy acid facial treatmentsdermnetnz.org
