LHA or BHA: same family, and only one of them tells you the dose

BHA and LHA are the same chemical family. LHA is salicylic acid with a fatty chain attached, which makes it more oil loving and slower to move.

The interesting question is not which molecule is better. It is that one of these is a heavily disclosed ingredient and the other is almost never disclosed, and that a third factor decides whether either one works at all.

Across the Korean labels we read: salicylic acid appears on 75 and five print a level. Capryloyl salicylic acid, the LHA, appears on 42 and one prints a level. Betaine salicylate, the other common Korean BHA form, appears on eight and none of them prints a level.

And the third factor is pH, which almost nobody publishes at all.

Why does pH decide this?

Salicylic acid works as a keratolytic in its un-ionised form. Raise the pH and the molecule converts to its salt, and the fraction that can do the job collapses.

This is not a subtlety you can ignore, because it is the difference between an exfoliating product and a product with an exfoliant listed on it. An acid in an alkaline base is present and inactive. The last product on this page demonstrates it precisely, and its brand was honest enough to publish the number that shows it.

So there are three things to look for, in descending order of how often you will find them.

1. Which salicylate is on the list.
2. How much of it there is.
3. What pH the formula sits at.

Most labels answer only the first.

sidmool Dr.Troub Skin Returning BHA essence

The clearest BHA label in our set, because it answers two of the three questions on one short list.

Salicylic acid is eighth of just 16 entries, printed at 0.5 percent. Sixteen entries is very short for a leave-on essence, and it makes the whole formula readable in one pass.

The brand also states a pH in the 4 range. That is the one property a buyer of a salicylic acid product most needs, and it puts the formula in the region where the acid is meaningfully un-ionised. The grading qualification is fair though: 4 range is a band, not a value. It commits to nothing between 4.0 and 4.9, and the activity difference across that span is not trivial.

The rest of the list is unusually clean: bamboo water first, arnica second, hibiscus third, with no fragrance, no alcohol and no oil anywhere.

One claim on the page does not survive. The copy advertises a meeting of a flower acid and a BHA. The BHA is there and quantified. There is no glycolic, lactic, mandelic, citric or malic acid on the list, and no AHA of any description. The three flower entries are extracts, and an extract is not an acid.

If you are pregnant, salicylic acid is on the caution lists and this is a leave-on product at a real level.

Disclosed: salicylic acid at 0.5 percent. pH stated as 4 range Fragrance-free: yes

beplain Mung Bean Pore Clearing LHA Toner

The only Korean label we found that prints an LHA level, and the figure is the story.

Capryloyl salicylic acid is nineteenth of 43 entries, at 10 parts per million. That is 0.001 percent.

Set that against 0.5 percent in the essence above. The one product that tells you its LHA dose tells you the dose is five hundred times smaller than the disclosed BHA in this article. Gluconolactone follows at twentieth with no figure, so there is a second acid here you also cannot bound.

We want to be clear that this is a good label rather than a bad one. beplain prints what it puts in, and it does so consistently: mung bean extract at 200 parts per million in position 14, mung bean seed extract at 5 parts per million at 21, and mung bean sprout extract at 0.1 parts per million at 30. Three forms of the headline botanical, three figures, spanning a factor of two thousand.

The statutory block also states plainly that no functional cosmetic notification applies, and the list agrees: no niacinamide, no adenosine, no arbutin, no UV filter. A brand that declines to imply a registration it does not hold is doing something most of this category does not.

There are twelve peptides at the end of the list, all undisclosed, which is the roster pattern rather than a dose. We wrote that up in peptides on a Korean label.

Buy this as a gentle daily wipe with a trace of acid. Do not buy it as your exfoliating step.

Disclosed: capryloyl salicylic acid at 10 parts per million Fragrance-free: yes

Isntree Chestnut BHA 0.9% Clear Toner

A percentage in the product name, and no percentage on the ingredient list.

The acid here is betaine salicylate, a salicylic acid derivative, and it sits sixth on the list, which is a genuine front of formula position. Betaine salicylate is oil soluble and partitions into sebum, so the mechanism matches what the product is sold for.

What is missing is everything that would bound it. No concentration is disclosed for the acid, no product pH is published, and no test is cited. The 0.9 percent in the name is not attached to any entry on the statement, so a reader cannot tell whether it describes the betaine salicylate, the salicylic acid fraction of it, or something else entirely.

This is worth dwelling on because it is the most common shape of a Korean acid product. The mechanism is right, the ingredient is real and well placed, and the number that would let you compare it against the essence at the top of this page is simply not there.

Betaine salicylate is on this product's pregnancy caution list.

Disclosed: nothing. Acid is sixth on the list Fragrance-free: yes

innisfree Volcanic BHA Pore Cleansing Foam

A disclosed BHA in a format that changes what the number means.

Salicylic acid is fifteenth of 26 entries at 5,000 parts per million, which is 0.5 percent, the same figure as the essence at the top. Volcanic ash follows at nineteenth at a disclosed 1,073 parts per million.

Two things then complicate it. This is a rinse-off, so contact time is tens of seconds and most of the acid leaves with the water. And potassium hydroxide is fifth with the fatty acids in front of it, which makes this a true soap base sitting in the alkaline range, where the active form of salicylic acid is a small fraction.

So a printed 0.5 percent in this product and a printed 0.5 percent in the essence above are not the same purchase, for two independent reasons.

What this product does hold is the strongest regulatory fact in the article: an acne functional cosmetic registration with a printed registration number, corroborated on a second surface. That is a real administrative status you can check, and it is rarer than it should be.

There is fragrance at position 14, high in a 26 item list. And the dust cleansing figure on the page, while attributed to a named testing house with a stated date and 33 adults, describes no protocol.

Disclosed: salicylic acid at 0.5 percent, in a rinse-off soap base Fragrance-free: no

Blanc Nature Acne Cleansing Foam

The product that proves the pH point, and the brand deserves credit for making it provable.

Salicylic acid is fourteenth of 40 entries. The brand publishes the pH at 8.5, plus or minus 0.5, and describes the product as mildly alkaline.

At pH 8.5 salicylic acid is essentially fully ionised. The pore clearing BHA action the product name implies does not happen at that pH, no matter how much acid is on the list. The acid is present and switched off.

The reason we like this example is how the number reached us. A customer asked the brand whether the product was weakly acidic, which is what buyers have been taught to want, and the brand answered with a number that is unflattering to it. That is a brand telling the truth against its own interest, and it is worth more than a page of claims.

Everything else follows from the same base: fatty acids at positions 2, 3, 4 and 6 neutralised by potassium hydroxide at 7. This is an efficient, high pH wash. It suits oily skin that tolerates soap and does not suit a compromised barrier.

Tea tree leaf oil is at position 40 of 40 and terpinen-4-ol at 39, so the antimicrobial framing rests on entries at the very end of a product you rinse straight off.

Salicylic acid is on this label's pregnancy caution list.

Disclosed: nothing for the acid. pH published at 8.5 Fragrance-free: yes

So which should you buy?

Buy the one that shows its work. In this category that means, in order: a printed concentration, a printed pH, and a leave-on format. One product on this page has the first two. Most products have neither.

If you want a real exfoliating step, a leave-on at a stated level in the low pH range is the thing to look for, and 0.5 percent is a useful anchor. Both of the highest salicylic acid figures we found land on exactly that number.

If you want gentleness, do not assume LHA gives it to you. The theory is sound, and the one Korean label that discloses an LHA level puts it at 0.001 percent, which is gentle for a reason that has nothing to do with the molecule. Undisclosed LHA products may be stronger or weaker and you cannot tell.

Watch the format and the base. A cleanser at 0.5 percent in an alkaline soap is not an acid treatment, and two products on this page are exactly that.

And do not stack. None of these should follow another acid or a retinoid in the same session, and an alkaline wash raises permeability for several minutes afterwards, so what you put on next goes further than its instructions assume. We covered frequency in how often to exfoliate, and the gentler acid class in what PHA actually is.

Common questions

Is LHA gentler than BHA?

The molecule is larger and more lipophilic, which is the basis for the claim, and it is plausible. In practice the Korean products carrying LHA do not disclose how much they hold, with one exception at 0.001 percent, so for a specific product on a shelf you usually cannot compare gentleness at all.

What pH does a BHA need?

Low enough for the acid to stay un-ionised, which is why products aiming at real exfoliation sit in the 3 to 4 range. The practical problem is that almost no Korean label publishes a pH, so this is a question you usually cannot answer.

Is betaine salicylate the same as salicylic acid?

It is a salicylic acid derivative and behaves as an oil soluble exfoliant, so the mechanism is the same family. It is a different entry on the label and a different molecular weight, so a percentage of one is not a percentage of the other.

Can I use a BHA cleanser instead of a BHA serum?

Not as a substitute. A wash has seconds of contact and most of it rinses away, and in a soap base the acid is largely inactive as well. A BHA cleanser is a cleanser that also has an acid on the list.

Is salicylic acid safe in pregnancy?

It appears on the standard pregnancy caution lists, which is why it shows up in the caution field on four of the five products here. Rinse-off exposure is lower than leave-on. This is a question for your own doctor rather than for a label.

If you have an acid product and cannot find either a level or a pH on it, send us the listing and we will look for both.