A bleeding drug repurposed for melasma and dark spots. Topical 2-5% shows promise in small trials; the oral prescription form is better studied.
Tranexamic acid blocks plasmin, an enzyme that in skin helps UV light and hormones switch on pigment cells and new blood vessels. Low-dose oral tranexamic acid is a recognized off-label prescription treatment for melasma.
Topical versions at 2-5% avoid the systemic clotting concerns. In small trials they reduced melasma, including a split-face trial where 3% tranexamic acid matched hydroquinone plus a steroid, with fewer side effects. Results take 8-12 weeks, and melasma returns without ongoing sun protection.
A handful of small trials (about 20-50 people, 12 weeks) show topical 2-3% tranexamic acid reduces melasma severity; one double-blind split-face trial found it comparable to 3% hydroquinone with dexamethasone. A 2017 review concluded efficacy is not yet adequately established. Evidence for other dark spots, such as sun spots and post-acne marks, is thinner.
50 Iranian women with melasma applied 3% tranexamic acid to one side of the face and 3% hydroquinone + 0.01% dexamethasone to the other for 12 weeks; both improved similarly, with significantly fewer side effects on the tranexamic acid side.
23 people with mostly mild melasma applied 2% tranexamic acid for 12 weeks; melasma scores improved in 22, and biopsies showed less epidermal melanin and lower endothelin-1. No control group; one author was from a cosmetics company.
Reviews oral, topical and injected tranexamic acid for melasma and concludes that its efficacy is not yet adequately established; more studies are needed.