
Licorice Root Extract: Some licorice-derived compounds are studied for uneven pigmentation. Mandelic Acid: Exfoliates skin; clinical evidence is mainly from professional acne peels.


Consider as an optional pigment ingredient; independent clinical evidence is limited.
Consider for exfoliation; evidence for acne comes mainly from supervised peels.
Can you use both?
A gentle pairing for dark marks, suited to darker skin.
Compare uses by strength of evidence. Evidence level describes confidence in a benefit, not its size.











Contains several active compounds: Glabridin and liquiritin have different actions. May help uneven pigmentation: Extracts and clinical evidence vary.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.

Loosens outer cells: An acidic formula helps reduce cell adhesion. Promotes shedding: Strength, pH and contact time affect the response.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.
Built from where each one usually sits in a routine. Introduce one at a time.
Licorice root extract contains multiple compounds, including liquiritin and glabridin. Whole-extract percentages do not reveal the dose of these individual compounds.
Choosing a strength: Look for the named extract or purified compound and evidence for the finished product.
Higher strengths: There is no established universal percentage range or proof that higher whole-extract concentrations improve pigmentation.
Formula matters: A small study of liquiritin cannot establish a recommended strength for every licorice extract, species, or formulation.
Mandelic acid skincare and office peels are different products. Controlled acne studies have used professional peels around 40–45%; those strengths are not a target for facial home use.
40–45%
Studied professional peels
Clinician-applied peels studied for mild-to-moderate acne. This describes specific procedures, not a recommended home concentration.
Choosing a strength: For home skincare, use the finished product’s label and your tolerance. Do not assume that a marketed serum reproduces an office peel study.
Higher strengths: Mandelic acid can still burn or irritate skin. Being described as a gentler acid does not make concentrated peels suitable for unsupervised use.
Formula matters: Acidity, vehicle and exposure time influence the effect; percentage alone cannot rank safety or compare mandelic acid with other acids.
Approximate windows, not promises.
First few weeksAssess tolerance first; pigment change is usually slower.
First few weeksAssess tolerance and texture; immediate softness can come from the base formula.
4–8 weeksSome studied regimens begin showing pigment improvement.
4–8 weeksSubtle changes may appear in some tested products; evidence varies.
8–12 weeksA useful review point for benefit and irritation.
8–12 weeksCompare photographs in the same lighting and reassess benefit.
3–6 monthsMany melasma trials assess results over three to four months; recurrence is common.
3–6 monthsPhotoaging trials often need several months; expect modest rather than dramatic change.
6–12 monthsLong-term use depends on the active; follow a monitored plan rather than extending treatment automatically.
6–12 monthsLong-term evidence is limited for many cosmetic actives; continue only if useful.
Botanical extracts can cause allergy or stinging; check the complete formula.
Can cause stinging, peeling or irritation; avoid active eczema and rosacea flares.
Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.
Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.
Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.
Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.
Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.
Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.
Data are limited; ask the clinician managing your pregnancy.
Low-strength leave-on acids are generally considered acceptable; avoid peels and ask the clinician managing your pregnancy.
On the skin. The finished product delivers licorice root extract in a particular vehicle.
Entering skin. No single molecular mass. The 500 Da guideline cannot be applied to this whole ingredient family or mixture.
Conversion. No activation step is established as necessary for its intended topical role.
Skin response. Compounds such as liquiritin and glabridin have different pigment-related actions; they are not interchangeable extracts.
Additional effects. Proposed pathways do not establish a measured depth of delivery or clinical benefit beyond the studies cited.
On the skin. The finished product delivers mandelic acid in a particular vehicle.
Entering skin. Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.
Conversion. No activation step is established as necessary for its intended topical role.
Skin response. Promotes shedding of surface cells; formula acidity and contact time influence irritation and effect.
Additional effects. Proposed pathways do not establish a measured depth of delivery or clinical benefit beyond the studies cited.
Consider as an optional pigment ingredient; independent clinical evidence is limited.
A 20-woman split-face study tested a specific liquiritin cream for four weeks with sun protection. It does not establish that all licorice extracts treat melasma or rosacea.
Consider for exfoliation; evidence for acne comes mainly from supervised peels.
A 50-person, 12-week trial compared 45% mandelic with 30% salicylic peels. It had no vehicle arm and does not establish the benefit of 5–10% home serums.
Sources