
Licorice Root Extract: Some licorice-derived compounds are studied for uneven pigmentation. Vitamin C: Some topical formulas modestly improve photodamaged skin and uneven tone.


Consider as an optional pigment ingredient; independent clinical evidence is limited.
Choose for an optional antioxidant and modest photoaging benefits; formula stability matters.
Can you use both?
Both brighten and are often found together.
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.

Helps limit oxidation: Ascorbic acid neutralizes reactive molecules. Supports collagen enzymes: It is a cofactor in collagen production.
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.
Vitamin C percentages only make sense when the form is named. Human studies include 5% L-ascorbic acid cream and a 15% L-ascorbic acid antioxidant combination; derivatives are different ingredients.
5%
15%
20%
Studied L-ascorbic acid cream
A lower-strength finished cream studied for photoaged skin. A modest percentage can still have clinical evidence.
Studied antioxidant combination
Studied with vitamin E and ferulic acid. The result supports that combination, not vitamin C in every formula.
Absorption-study benchmark
A pig-skin study found maximal delivery at this concentration under its test conditions. It is not proof of the best clinical dose.
Choosing a strength: Check whether the product contains L-ascorbic acid or a derivative. Percentages of different forms are not interchangeable.
Higher strengths: A higher number is not automatically better and may be less comfortable. A laboratory delivery result is not a recommendation to maximize strength.
Formula matters: Acidity, stability, packaging and the other ingredients affect performance. A derivative serum cannot be ranked against L-ascorbic acid by percentage alone.
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.
Acidic formulas may sting; stop for persistent redness or a rash.
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. Individual tolerance matters more than an ingredient’s reputation for being gentle.
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.
Topical vitamin C is generally considered acceptable in pregnancy; check the complete formula with your clinician.
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 vitamin c 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. Ascorbic acid participates in antioxidant and collagen pathways; stability and delivery limit topical performance.
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.
Choose for an optional antioxidant and modest photoaging benefits; formula stability matters.
Small controlled trials support specific formulas over three to six months. Derivatives have different masses and evidence; they cannot be assumed interchangeable with L-ascorbic acid.
Sources