AHA, BHA and PHA Are Three Exfoliating Acids That Work at Different Depths
Chemical exfoliation sounds like one idea, but it splits into three families that behave very differently on skin. AHAs like glycolic acid are the water soluble group. Glycolic is the smallest molecule in the AHA family, which lets it travel a little deeper and act quickly on the surface. It loosens the bonds holding dead cells together, so tone looks more even, texture feels smoother, and the serums layered on top absorb better. BHA is a different animal. Salicylic acid is the one acid here that dissolves in oil, and that single trait sends it somewhere AHAs cannot reach: inside the pore lining, where trapped oil and buildup collect. That oil solubility is why it became a staple for blemish-prone skin and why it pairs so naturally with oil and sebum control routines.
PHA is the newest and gentlest branch. Gluconolactone, made by fermenting glucose, has a noticeably larger molecule than either AHA or BHA. That size is the whole point: it sits and works on the surface slowly instead of rushing into deeper layers, so it exfoliates while keeping irritation low. It also carries multiple hydroxyl groups, which means it draws in and holds water at the same time it lifts dead cells. Instead of the tight, dry feeling some acids leave behind, PHA usually leaves skin feeling plumper and more comfortable. It is the acid people reach for when stronger exfoliants have felt like too much, which makes it a friendly starting point for sensitive, reactive skin.
How Do You Choose and Combine AHA, BHA and PHA?
Start from what your skin actually wants to change. Reach for glycolic and other AHAs when the goal is smoother texture and a more even look, and lean on salicylic when clogged pores and congestion are the main story. If acids have stung in the past, gluconolactone is the softer on ramp. Concentration matters as much as the acid itself. Korean formulas often keep salicylic low, around 0.5 to 2 percent, in pads and toners that suit daily use, while stronger glycolic serums are better a couple of nights a week until skin adapts. Begin once or twice weekly, use acids at night, and apply daily sunscreen the next morning without exception, since fresh exfoliation leaves skin more sensitive to light.
Combining is where routines go right or wrong. Salicylic and niacinamide are one of the most reliable pairs, since niacinamide supports sebum balance while the acid clears the pore. Follow an acid step with centella and cica when you want skin to look calm and settled afterward. What you should not do is stack strong exfoliants on the same night: layering AHA or BHA with retinol in one sitting raises the risk of irritation, so split them across alternate evenings. PHA is the exception to most of these rules. Its gentle profile sits comfortably alongside retinol during an adjustment phase and works with niacinamide for tone and texture at once, which is why it doubles as a bridge for skin that could not tolerate the other two.
Explore related edits: Acne & Blemish, Niacinamide, and Pore Care.
Frequently Asked Questions About AHA, BHA & PHA
What is the difference between AHA, BHA and PHA?
AHAs such as glycolic acid are water soluble and work on the skin surface to smooth texture and even out the look of tone. BHA, meaning salicylic acid, is oil soluble, so it travels into the pore for a deeper clean that suits congestion and blemish-prone skin. PHA, such as gluconolactone, has a larger molecule that works slowly on the surface with far less irritation, plus water-binding and antioxidant properties the others usually lack.
Which acid should I use for clogged pores and blackheads?
Salicylic acid is the most targeted choice. Because it dissolves in oil, it reaches into the pore channel and breaks up the oil and buildup that collect there, both helping keep new congestion from building and softening the look of existing blackheads. With regular use over about 4 to 8 weeks, most people notice a clearer look to pore texture.
Can I use these acids every day?
It depends on the acid and the strength. Low concentration salicylic pads and toners, around 0.5 to 1 percent, are generally fine for daily use, while stronger glycolic serums are better two or three nights a week to start. Gluconolactone has the highest daily tolerance of the three and suits sensitive skin, though daily sunscreen still applies the morning after any acid.
Can I use an AHA or BHA on the same night as retinol?
It is best to keep them apart. Layering glycolic or salicylic with retinol in one routine raises the risk of irritation, so split these strong actives across alternate evenings, for example acid one night and retinol the next. Gluconolactone is the gentle exception and pairs more comfortably with retinol.
Which acid is best for sensitive skin?
Gluconolactone, a PHA, is the usual pick. Its larger molecule works more slowly on the surface, so it exfoliates with much less of the sting or redness that stronger acids can cause, and its water-binding groups leave skin feeling comfortable rather than tight. It is a safe transition point for skin that has not gotten along with salicylic or glycolic.
Do I really need sunscreen after using acids?
Yes. Freshly exfoliated skin is more sensitive to light, so daily sunscreen the next morning is essential to protect the look of your tone and keep the results of your routine on track. PHAs are less sensitizing than AHAs, but sun protection after any acid is still the standard step.
Which acids does niacinamide combine well with?
Niacinamide pairs especially well with salicylic acid, since it supports sebum balance while the acid keeps pores clear. It also works alongside gluconolactone to target uneven-looking tone and texture at the same time. These are gentle, complementary combinations rather than competing strong actives.
Are the AHA, BHA and PHA products at Vionine authentic?
Yes, every acid and exfoliant at Vionine is 100% authentic Korean skincare, sourced from the brands and shipped with fast US shipping.