Also known as: Gluconolactone, lactobionic acid
What Is PHA (Polyhydroxy Acids)?
PHAs, or polyhydroxy acids, are a newer generation of hydroxy acids. The most common in skincare are gluconolactone and lactobionic acid, which is gluconic acid bonded to a sugar. Like AHAs, they loosen the connections between dead cells on the skin's surface. Unlike AHAs, their molecules are large and carry several water-attracting hydroxyl groups.
That structure changes how they behave. Because they penetrate slowly, PHAs exfoliate more gently than glycolic acid or even lactic acid, with less stinging. The extra hydroxyl groups also make them humectants, so they help skin hold water while they smooth it. Both gluconolactone and lactobionic acid have also been described as having antioxidant properties.
PHAs have become popular in Korean toners, pads and essences aimed at sensitive skin and beginners. The trade-off is that results build more slowly, and they are not designed to clear deep pore congestion the way salicylic acid does. Think of them as a maintenance exfoliant for gradual smoothness and glow.
PHA (Polyhydroxy Acids) Benefits for Skin
- Exfoliates gently with a low risk of stinging.
- Adds hydration while smoothing the surface.
- Helps brighten dull skin with regular use.
- Suitable for many sensitive and dry skin types.
- Offers mild antioxidant support.
How to Use PHA (Polyhydroxy Acids)
Many PHA products are gentle enough for daily use, often in the form of a toner or pad applied after cleansing. If you are unsure where it belongs in your lineup, toner vs essence explains the difference between the two steps. Follow with a soothing layer, such as a serum with panthenol or centella, and a moisturizer.
Even though PHAs are generally considered less likely to increase sun sensitivity than AHAs, any exfoliation leaves skin more exposed, so keep wearing a broad-spectrum sunscreen every morning. If your skin handles a PHA well for several weeks and you want more visible smoothing, that is a reasonable time to consider stepping up to a low-strength lactic acid.
Side Effects & Precautions
PHAs are well tolerated by most people, but mild tingling can still happen, especially on freshly shaved or chapped skin. If your barrier is already damaged, pause all exfoliants until it recovers.
Some PHA products are combined with AHAs or BHAs for a stronger effect. Check the ingredient list if you chose a PHA product specifically because your skin is reactive.
Use caution when combining
- Layering with other acid toners in the same routine.
- Retinoids on the same night if your skin is easily irritated.
Frequently Asked Questions
Are PHAs better than AHAs?
They are gentler rather than better. PHAs are a good fit for sensitive or dry skin and for beginners, while AHAs usually deliver faster, more noticeable smoothing for skin that can tolerate them.
Can I use a PHA every day?
Many PHA toners are formulated for daily use. Start with every other day if you are cautious, and increase if your skin stays calm and comfortable.
Do PHAs help with acne?
They can help with mild surface roughness and dullness, but they are not the strongest choice for clogged pores. Salicylic acid usually works better for blackheads and breakouts.