Ingredient glossary
Mandelic Acid
On your shelf ✓What Mandelic Acid does for your skin, who it suits, and what to watch for.
INCI: Mandelic Acid
In short: Mandelic Acid delivers exfoliation and brightening, suits combination and oily skin best, and the evidence behind it is moderate. One thing to know: clear it with your doctor if pregnant; needs the right pH to work.
- What it does
- Exfoliation, brightening
- Best for
- Combination, Oily skin
- Watch out
- Clear it with your doctor if pregnant; needs the right pH to work
- Evidence
- Moderate
- How long
- Never measured
The molecule
The Glow take
One of the ingredients I trust most.
When your goal is calming breakouts and congestion, Mandelic Acid delivers, with a solid amount of evidence behind it. It only performs at the right pH, so it is worth buying from brands that get the formulation details right.
— Maya
What it does
- exfoliation
- brightening
- anti acne
moderate evidenceClinical and review data show mandelic acid improves acne, hyperpigmentation and texture with fewer irritation reports than glycolic acid at similar strengths.
On a label: works best above 5%.
The AHA family, at a glance
7 AHA entries in the base, Mandelic Acid among them. 5 of the 7 are a supporting active.
- Glycolic acid76 Da
- Lactic acid90 Da
- Ammonium lactate107 Da
- Malic Acid134 Da
- Tartaric Acid150 Da
- Mandelic Acid152 Da
- Citric Acid192 Da
The pH it needs
The un-ionised acid (pKa 3.41) exfoliates; in pig skin it worked at pH 4 but lost most of its effect at pH 4.5.
pH 5.0 is above 4.5, past the line the study drew (pig skin).
Mandelic acid also demonstrated excellent exfoliation effects at pH 4, but at pH 4.5, even at 3%, its exfoliation efficacy significantly decreased to less than 40% compared to PHA.
Drag the handle along the line. Only what was measured is drawn; between the marks nothing was. Your skin's surface: about 4.7 at rest, 5.1 on a normal day.PMID 18489300PMID 38881052
Who it's for, and who should skip it
Tends to suit
- oily
- acne prone
- combo
- sensitive
Approach with care
- very sensitive
- compromised barrier
- Clogs poresLow
- Irritation riskLow
- pH-dependentIts effect depends on the product's pH
How it fits each skin type
- DryNeutral
- CombinationSuits
- OilySuits
- SensitiveTake care
Often chosen for acne prone. Take extra care if any of these apply to you: compromised barrier.
Where it fits in your routine
Increases sun sensitivity while you are using it, so sunscreen matters more than usual.
Why we say this
- An alpha hydroxy acid working by the same stratum-corneum thinning as glycolic and lactic acid, so FDA's class-wide AHA labeling recommendation covers a leave-on mandelic acid product.
- The evidence base is glycolic and lactic acid only, and mandelic is a larger, slower-penetrating molecule, so the effect size is likely smaller than glycolic's.
US FDA guidance for industry, labeling for cosmetics containing alpha hydroxy acids (2005), which addresses alpha hydroxy acids as a class
Nobody has published how long this takes to work.
What is known, and what is missing
- Measured on: acne lesion count and pigment/tone improvement.
- The clinical work is in-office peel series - roughly 45% mandelic acid applied fortnightly, compared with 30% salicylic acid over a few months - which is a completely different exposure from the 5-10% leave-on products this base describes at effective_above_5%.
- No vehicle-controlled trial of a leave-on mandelic product reports when any endpoint first changed.
- Because its larger molecule penetrates more slowly, borrowing a glycolic acid timeline would overstate it.
Peel-series comparisons of 45% mandelic against 30% salicylic acid in acne (described, no PMID asserted); no leave-on time-course study located.
Plays well with
- niacinamide
- azelaic acid
- humectants
Mandelic Acid, answered
Is Mandelic Acid safe during pregnancy?
Clear it with your doctor first. Mandelic Acid is flagged as use-with-caution during pregnancy and breastfeeding, so check with your doctor or midwife before adding it.
Who should avoid Mandelic Acid?
Approach Mandelic Acid with care if any of these apply to you: very sensitive and compromised barrier.
What concentration of Mandelic Acid actually works?
Research tends to show Mandelic Acid starts pulling its weight above 5%. If a brand prints the percentage, that is the number to look for.
During pregnancy
Treat Mandelic Acid as a maybe rather than a yes for now. It is flagged as one to use with caution while pregnant or breastfeeding, so it is worth clearing before you carry on.
When in doubt, check with your doctor or midwife. They outrank any website, including this one.When it is worth booking →
On the map
- careful withAdapaleneBetaine SalicylateLactic acidTretinoinAmmonium lactateand 23 more
- fine withNiacinamide
Compare Mandelic Acid with
11 comparisons built, the 2 most looked-up above.
Can you mix Mandelic Acid with
27 pairings built, the 4 most looked-up above.
This, for every label you own
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Sources & how we reviewed this
What changed on this page
- : the pH it needs
- : the highest dose tested
- : what the EU regulates