AHA vs BHA vs PHA vs LHA in Korean Skincare
AHA is usually the clearest choice for rough, flaky surface texture; BHA is the more targeted option for oily-looking pores and blackheads; PHA can suit a routine that needs surface exfoliation with a more hydrating formula; and LHA is a salicylic-acid derivative whose finished-formula evidence is more limited. The acronym is only the first filter. Concentration, pH, vehicle, contact time, frequency, and the rest of your routine decide how strong a product actually behaves.
This distinction matters in Korean skincare because the same acid family can appear in a cleanser, watery toner, toner pad, serum, peeling gel, or wash-off treatment. A rinse-off BHA cleanser and a leave-on BHA liquid do not create the same exposure. A low-pH AHA peel and a buffered toner are not interchangeable. Choose the complete product and its directions, not the ingredient family in isolation.
Updated July 24, 2026. Evidence and live product status were rechecked for this revision.
The four acid families at a glance
Use the family name to identify the likely job, then use the finished formula to judge exposure and tolerability.
| Family | Common names | Most useful starting question | Important limitation |
|---|---|---|---|
| AHA | Glycolic, lactic, mandelic acid | Is roughness, flaking, or uneven surface texture the main concern? | Strength varies with acid type, concentration, pH, and formula. AHA use can increase sun sensitivity. |
| BHA | In cosmetics, usually salicylic acid | Are blackheads, excess oil, or congested-looking pores the main concern? | A cleanser has shorter contact than a leave-on treatment. Irritation can still occur. |
| PHA | Gluconolactone, lactobionic acid | Do you want surface exfoliation in a formula that may also support hydration? | Gentler positioning does not make every PHA formula non-irritating or suitable for daily use. |
| LHA | Capryloyl salicylic acid | Does the exact formula use LHA for gradual surface renewal? | Evidence is smaller than for glycolic or salicylic acid, and the 2024 safety review found available data insufficient for a general conclusion. |
What changes from AHA to BHA, PHA, and LHA
AHA
Choose it when rough surface texture leads
Alpha hydroxy acids loosen the bonds that hold surface cells together. Glycolic and lactic acid are common cosmetic AHAs; mandelic acid also appears frequently in Korean exfoliating products. The FDA notes that exfoliation depends on acid type, concentration, pH, and other ingredients, so percentage alone cannot rank a product.
AHA is the most direct family to consider when skin feels rough, looks flaky, or catches makeup unevenly. The main safety distinction is sun sensitivity. FDA research found increased UV sensitivity during use of an AHA cream, and current FDA guidance advises sun protection while using AHA products.
BHA
Choose it when blackheads and oily-looking pores lead
In cosmetic language, BHA usually means salicylic acid. Its oil-compatible character makes it relevant when blackheads, shine, and congested-looking pores are the main concern. This is the practical reason BHA is separated from AHA in comparison guides.
Format is the decision that often gets skipped. A gel cleanser is rinsed away after brief contact. A toner pad adds formula exposure and wiping friction. A leave-on liquid stays on the skin and can be easy to over-apply. Choose one BHA lane before adding another acid product.
PHA
Choose it for surface exfoliation with hydration context
Polyhydroxy acids such as gluconolactone and lactobionic acid are used in formulas that combine surface renewal with humectant properties. A small split-face study of gluconolactone found increased measured hydration, but it included only 16 healthy women and tested specific solutions. It does not prove that every PHA toner hydrates every user.
PHA can be easier for some routines to fit, but it is not an irritation exemption. Concentration, pH, supporting ingredients, application method, and frequency still determine tolerability. The official Biodance page identifies its Skin Refining Mild PHA Toner as an 8% PHA formula and advises patch testing for highly reactive skin.
LHA
Choose only from the complete formula
LHA usually refers to capryloyl salicylic acid, a lipophilic derivative of salicylic acid. Earlier reviews describe slower penetration and gradual exfoliation, while small studies evaluated professional-strength peels. Those findings do not establish that every LHA cosmetic is more effective or less irritating than every BHA or PHA product.
In 2024, the Expert Panel for Cosmetic Ingredient Safety concluded that available data were insufficient to determine the safety of capryloyl salicylic acid under intended cosmetic conditions of use. That is not a declaration that LHA is unsafe. It means the evidence base does not support a universal safety shortcut.
Do not describe a cosmetic acid as treating acne, scars, or pigmentation unless the exact product is labeled and regulated for that purpose.
Choose by concern, then check strength and format
- Name one primary concern. Choose rough surface texture, blackheads and oil, or a lower-friction maintenance step.
- Check the format. Cleanser, liquid toner, pad, serum, and peel create different contact times and friction.
- Read the acid name and concentration when disclosed. A family name without formula context is not a strength rating.
- Follow the label frequency. Gentle and daily are positioning terms, not permission to ignore irritation.
- Keep one main exfoliating product in the test period. A second acid, scrub, retinoid, benzoyl peroxide, or spicule product can make the result harder to interpret.
If your concern is mostly blackheads and visible pore congestion, continue with How to Minimize the Look of Pores with K-Beauty. For broader breakout-prone routine planning, use the Korean Skincare Routine for Acne-Prone Skin. You can also browse the existing pore-focused collection or roughness-focused collection.
How to introduce an exfoliating acid
Start with a stable base: cleanser, moisturizer, and daytime sunscreen. Add one exfoliating product according to its label. Keep the amount, application method, and other active products unchanged for the first several uses so you can identify what caused improvement or irritation.
Do not use burning as a performance signal. Persistent stinging, redness, swelling, peeling, unusual tightness, or tenderness means the schedule or formula is not currently tolerable. Stop the exfoliant, return to familiar basics, and seek medical advice for severe or persistent reactions.
A practical evening order for a leave-on acid is cleanser, acid step, hydrating serum if useful, and moisturizer. A rinse-off acid cleanser replaces the cleansing step rather than becoming an extra layer. Sunscreen remains important during daytime, particularly with AHA use.
Five live product formats that illustrate the decision
These products were active, linked to valid product pages, and had positive sellable inventory when checked. They are examples of different format decisions, not a ranking. Current labels and product pages remain the source of truth.
Dr.Belmeur AHA PHA Exfoliating Toner 100ml
A watery leave-on toner with 5% AHA and 5% PHA according to the official THEFACESHOP page. It fits a surface-texture goal, but it already combines two exfoliating families, so avoid treating it as a neutral hydrating toner beside another peel.
View current details
MEDITHERAPY A Clearing Active BHA Facial Gel Cleanser 150ml
A short-contact BHA gel cleanser for readers who prefer a rinse-off format. Its exposure is not equivalent to a leave-on liquid, so compare it by role and directions rather than by the BHA label alone.
View current details
BIODANCE: Skin Refining Mild pHA Toner (150ml)
An 8% PHA toner according to the official Biodance page. It illustrates a PHA-led leave-on route for surface texture and hydration support, while still requiring patch testing, label-led frequency, and care around duplicate exfoliants.
View current details
WELLAGE Real Hyaluronic Peeling Solution 30ml
A treatment-style AHA, PHA, and succinic-acid peeling solution with a thick, adhesive texture in the live Shopify record. Its role and exposure matter more than the number of acids named on the front.
View current details
HANYUL Ginkgo Leaf Pore Resurfacing Serum 40ml
A watery post-toner serum with 10% niacinamide and an 8.4% AHA, BHA, and PHA blend according to the official HANYUL formula. It illustrates a multi-acid serum format, so avoid stacking it casually with another exfoliating step.
View current detailsA five-step decision sequence
FAQ
Can I use AHA and BHA together?
Some finished formulas combine them, but separate AHA and BHA products do not need to be layered. Start with one primary concern and one acid product. If you later combine products, keep within both labels and reduce frequency at the first sign of persistent irritation.
Is PHA always better for sensitive skin?
No. PHA formulas may be easier for some people to tolerate, and gluconolactone can have humectant properties, but sensitive skin includes many different conditions. The exact concentration, pH, vehicle, frequency, and current skin condition still matter.
Is LHA the same as BHA?
LHA usually means capryloyl salicylic acid, a lipophilic derivative of salicylic acid. It is related to the BHA conversation but is not interchangeable with salicylic acid. Evidence and use levels differ, so follow the exact product rather than substituting one acronym for another.
Which acid is best for blackheads?
In cosmetic skincare, salicylic acid is the most directly relevant starting ingredient for blackheads because it is used for pore-focused exfoliation. A leave-on formula and a rinse-off cleanser create different exposure, and persistent acne may require medical treatment rather than a stronger cosmetic routine.
Do exfoliating acids require sunscreen?
Use daytime sun protection as part of an exfoliating routine. FDA guidance specifically warns that AHA products may increase sun sensitivity and also recommends sun protection with BHA cosmetics.
References and evidence limits
- U.S. Food and Drug Administration: Alpha Hydroxy Acids
- U.S. Food and Drug Administration: Beta Hydroxy Acids
- Gluconolactone and measured skin hydration, 2021
- Review of lipohydroxy acid use, 2016
- Safety reassessment of capryloyl salicylic acid, 2024
- Official Biodance Skin Refining Mild PHA Toner page
- Official THEFACESHOP Dr.Belmeur AHA/PHA Toner page: au.thefaceshop.com/products/dr-belmeur-aha-pha-exfoliating-toner
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