Ingredient Guide
PHA (Polyhydroxy Acids)
PHAs are the gentlest category of exfoliating acids, including gluconolactone and lactobionic acid, offering surface exfoliation with lower irritation than AHAs, making them well suited to sensitive skin.
Evidence profile
How confident is this recommendation?
Confidence is shown in plain categories, not a numerical trust score.
Reasonable evidence for gentle exfoliation as a category, with individual PHAs like gluconolactone and lactobionic acid each having their own supporting research.
A similar range to AHAs, but generally better tolerated at comparable concentrations.
This is where PHAs have their clearest practical advantage as a category.
Gentler action generally means more gradual results than stronger AHAs.
Individual PHAs aren’t always tested head-to-head under identical conditions.
What it is
The gentlest category of exfoliating acids.
PHA stands for polyhydroxy acid, a category that includes gluconolactone, lactobionic acid and others. Compared with AHAs, PHA molecules are larger, meaning they penetrate more slowly and superficially, generally resulting in gentler exfoliation.
Some PHAs also have humectant properties, offering a hydration benefit alongside their exfoliating role, distinguishing them further from most AHAs.
Evidence at a glance
Useful evidence, with important limits.
Gentle exfoliation with lower irritation
Reasonable evidence across the category supports PHAs as a lower-irritation alternative to AHAs for surface exfoliation.
Limit: Gentler action may mean more gradual results compared with stronger AHAs.
Humectant and antioxidant properties
Some PHAs, like lactobionic acid, have additional supportive properties beyond exfoliation.
Limit: This dual-action profile varies by specific PHA and is less studied than the core exfoliating effect.
Concentration guide
Similar range to AHAs, but generally gentler at comparable strengths.
| Concentration or form | How to interpret it | Practical use |
|---|---|---|
| 5% | A gentle starting point. | Suitable for very sensitive or PHA-naive skin. |
| 8–10% | A common, moderately active leave-on strength. | Still generally well tolerated compared with equivalent AHA concentrations. |
Skin Candid view: Because PHAs are gentler by nature, they can often be used more frequently than equivalent-strength AHAs, though building tolerance gradually remains a sensible approach.
How to use it
A flexible, gentle acid category suitable for regular use.
Gentle doesn’t mean instant: PHA exfoliation is gradual by design; consistency matters more than speed.
Using it with other ingredients
Reduce routine complexity before testing combinations.
Retinol
The gentle profile of PHAs makes them a reasonable pairing option, though introducing one active at a time is still wise.
Hyaluronic Acid
Both support hydration alongside PHA’s exfoliating role.
Side effects and caution
Generally well tolerated, even for reactive skin.
- Irritation is less common than with AHAs at comparable concentrations.
- Still increases mild sun sensitivity; daily sunscreen remains sensible practice.
- Discontinue if unexpected irritation develops, though this is less common with PHAs than AHAs.
Frequently asked questions
PHA (Polyhydroxy Acids), without the pressure to tolerate everything.
What are the most common PHAs used in skincare?
Gluconolactone and lactobionic acid are the two most commonly used PHAs, each with individual supporting research.
Are PHAs suitable for very sensitive skin?
Yes, PHAs are often specifically recommended for sensitive skin that doesn’t tolerate AHAs or BHA well.
Can I use PHA every day?
Many people tolerate PHAs more frequently than AHAs, though starting gradually and monitoring your skin’s response is still reasonable.
Related decisions
Continue from the question you are actually trying to solve.
Sources reviewed
Primary evidence and medical guidance behind this page
- American Academy of Dermatology: How to safely exfoliate at home
- NIH NCBI Bookshelf (StatPearls): Moisturizers
Sources support the general editorial conclusions shown here. They do not prove that every product containing this ingredient will produce the same result.