Tranexamic acid (also known in cosmetics as 传明酸, and listed in China by its INCI name 氨甲环酸) is a water-soluble brightening active that helps reduce the look of uneven tone and post-inflammatory dark spots by calming the skin’s pigment-signaling pathway rather than bleaching it. If you are planning an even-tone or post-acne serum, the practical questions are use level, stability in your base, what to pair it with, and how to keep the claims compliant.
What is tranexamic acid and how does it work?
Tranexamic acid is a synthetic derivative of the amino acid lysine. In medicine it is used as an antifibrinolytic, but in skincare its interest comes from a different route: it inhibits plasmin, an enzyme that also helps drive melanin-stimulating signals and low-grade inflammation in the skin. By keeping plasmin activity in check, tranexamic acid reduces the cascade that leads to excess pigment after sun exposure or breakouts. What consumers notice is a more even-looking complexion and faded dark marks, not a change to normal skin tone.
What use level should you formulate at?
In finished cosmetics, tranexamic acid is typically used around 2–3%. Japan permits it as a quasi-drug whitening ingredient at up to 3%, which is the reference point many brands benchmark against. The exact maximum allowed in your market can differ, so confirm the current positive-list limit before you lock the formula — China, the EU, and other regions each maintain their own inventory, and the number moves over time. A common starting point for a serum is 2–3%; using more is not automatically better, and claims still have to stay within cosmetic scope.
How stable is it, and how do you add it?
Tranexamic acid is water-soluble and stable across the pH range of most cosmetic emulsions, which makes it straightforward to work with. It tolerates normal production heating, so it can be added during the water-phase or cool-down stage depending on your process. Because it is a small, stable molecule, you do not need special encapsulation to keep it active in a standard serum or lotion. The bigger formulation risk is not stability but claim wording, covered below.
What pairs well with tranexamic acid?
Tranexamic acid is often combined with other gentle brightening actives so the formula approaches uneven tone from more than one angle. Common, well-tolerated pairings:
| Paired with | Why it works | Formulator note |
|---|---|---|
| Niacinamide | Supports barrier and tone via a different mechanism | Stable together; a frequent first choice |
| Vitamin C derivatives (MAP, AA2G) | Antioxidant plus tone support | Use a derivative, not pure L-ascorbic, for stability |
| Arbutin | Another melanin-pathway modulator | Watch combined use levels against local limits |
| Licorice or soothing extracts | Calms the post-inflammatory side | Helps when the base targets acne marks |
The aim is synergy through different mechanisms, not stacking more of the same active. Keep each component within its own allowed range.
Which claims are allowed, and which cross the line?
This is where brands get into trouble. Tranexamic acid is sometimes discussed in medical contexts for melasma, but a cosmetic product cannot claim to treat a condition. Keep your claims anchored to appearance:
- Allowed framing: "helps improve the look of dark spots," "supports a more even-looking tone," "helps fade the appearance of post-acne marks."
- Crosses the line: implying the product treats melasma or any skin condition as a disease, implying it carries drug-like efficacy, or promising to remove normal pigmentation.
Documentation matters: keep the substantiation behind your tone claims, and make sure the wording matches what a cosmetic is allowed to say in each market you sell in.
Which product forms suit it?
Because it is water-soluble and low-irritation, tranexamic acid fits serums, essences, lotions, toners, and sheet masks. Serums and essences are the most common home for an even-tone claim because the consumer expects a concentrated step there. If you build it into a post-acne routine, a light lotion or toner can carry a lower use level while the serum carries more.
Formulation checklist
- Set the use level at 2–3% and confirm the local maximum before locking.
- Add during water-phase or cool-down; no special stabilization needed.
- Pair with niacinamide or a vitamin C derivative for a multi-angle tone story.
- Keep claims to appearance; document the substantiation per market.
If you are scoping an even-tone or post-acne line and want a second opinion on use level, pairing, and claim wording before you commit to a formula, our team can review the plan with you.