Ingredient Beauty BenefitsBrightening actives
With the retinoids, what came apart was the order of strength. Here what comes apart is the official list and the evidence.
Korea notifies nine whitening actives. And the two in this table that went head-to-head with hydroquinone and tied are not among them.
- thiamidol — tied with 4% hydroquinone (moderate). Not among the nine
- cysteamine — tied with hydroquinone (moderate). Not among the nine
- arbutin — it is a notified active. And its efficacy finding is one 30-person pilot, used in a combination (early)
Being notified is not a mark that something was shown to work. It is a mark that a product with that amount may carry that wording. Read the two together and being on the list reads as evidence while being off it reads as not working. Both readings are wrong.
And in this table, read the title column. Some of these are sold as brighteners while their moderate evidence is not about pigment at all.
- vitamin C — the moderate evidence is about a derivative and eye-area wrinkles. And its page records that pure ascorbic acid is not among the notified actives
- azelaic acid — filed under pigmentation, but its moderate finding is about rosacea
- kojic acid — the moderate finding is not about it alone. It is what happened when it was added to a gel that already worked
- niacinamide — notified, and pigmented spots did fall in its 50-person trial. But the control was a moisturiser, not a vehicle, and fine lines, yellowing and red blotchiness were measured all at once
One more thing splits here — applied versus swallowed. Glutathione lowered the melanin index in a split-face trial of the topical form (moderate), but the oral trial in 83 people found no significant difference from placebo. The same substance splits by route.
Hexylresorcinol had niacinamide alone as its control — the design this site keeps wishing for — and no participant count was published.
Finally, nothing in this set has strong evidence. The highest is moderate. And the thickest evidence in pigmentation is not in this table — it is sunscreen. Without blocking the sun, none of the above holds. To start from the cause, go to the pigmentation page.
| Item | Grade | Endpoint | Randomised trials in humans | Comparator · Funding |
|---|---|---|---|---|
| ThiamidolIngredient · 0.2%It tied with 4% hydroquinone | Moderate evidence | scores from blinded assessors | 1 · 50 participants · 13 weeks | another active ingredientnot declared |
| CysteamineIngredient · 5%It tied with hydroquinone — and with kojic acid | Moderate evidence | scores from blinded assessors | 2 · 20–72 participants · 16 weeks | another active ingredientnot declared |
| Tranexamic acidIngredient · 3%3% cream against 4% hydroquinone, half a face each | Early research | scores from blinded assessors | 1 · 20 participants · 8 weeks | another active ingredientnot declared |
| 4-ButylresorcinolIngredient · 0.1%Melanin index fell in a 20-person split-face trial | Moderate evidence | instrument measurement | 1 · 20 participants · 8 weeks | vehicle (same formula minus the active)not declared |
| Kojic acidIngredient · 2%The same gel on both sides, kojic acid added to one | Moderate evidence | scores from blinded assessors | 1 · 40 participants · 12 weeks | vehicle (same formula minus the active)not declared |
| ArbutinIngredient · 5%No difference from a triple-combination cream on objective measures — a 30-person pilot | Early research | scores from blinded assessors | 1 · 30 participants · 16 weeks | another active ingredientnot declared |
| NiacinamideIngredient · 5%Fine lines, yellowing, red blotchiness and spots decreased — 50 people, 12 weeks | Moderate evidence | scores from blinded assessors | 1 · 50 participants · 12 weeks | a plain moisturisermanufacturer-funded |
| Vitamin C (ascorbic acid)Ingredient · 1–3%One derivative improved periorbital wrinkles in an 8-week trial | Moderate evidence | scores from blinded assessors | 1 · 69 participants · 8 weeks | vehicle (same formula minus the active)not declared |
| GlutathioneIngredientTopical: melanin index fell in a 46-person split-face comparison | Moderate evidence | instrument measurement | 1 · 46 participants · 8 weeks | vehicle (same formula minus the active)not declared |
| HexylresorcinolIngredientIt beat niacinamide alone — but the abstract gives no participant count | Early research | instrument measurement | 1 · sample size not reported · 12 weeks | another active ingredientmanufacturer-funded |
| Azelaic acidMedicine · 15%Better than placebo, on evidence the reviewers rated as low quality | Moderate evidence | scores from blinded assessors | 2 · sample size not reported | vehicle (same formula minus the active)publicly funded, not declared |
This is not a ranking
This site does not rank or star-rate ingredients and procedures. The comparison tables are no different.
The row order is the layer and the seed order, and being higher up does not mean better. Where several items share a grade, adding any second sort key would make that key another ranking, so there is none.
And every row carries the title of the finding that grade hangs on. Without it, the row reads as 'this ingredient's score'. It is the same reason we do not average when a page has several findings — an average is a number nobody measured.
Which finding goes in the table is a rule too. If the comparison names a question, that finding (as with the three measured against hydroquinone in the brightening set); if it names none, the highest-graded finding. Entries marked as ingredient data — facts from an ingredient list or a regulatory document — are not efficacy claims, so they are never the representative.