Melasma is a common acquired hyperpigmentation disorder that presents as pale to dark brown hyperpigmented patches without conscious symptoms, usually symmetrically distributed, without inflammatory manifestations or scaling. The etiology is complex and is associated with genetics, sun exposure, pregnancy, oral contraceptives, thyroid abnormalities, cosmetics, and medications. Current treatment methods, including oral vitamins, topical depigmentation agents, chemical peeling and laser and photon therapy, are effective in treatment, but all treatment methods have shortcomings. I. Mechanism of treating melasma Tranexamic acid is an antifibrinolytic drug, which is widely used in clinical practice to treat various bleeding disorders. It exerts antifibrinolytic effect by blocking the lysine binding site on the fibrinogen molecule, does not increase prothrombin activity, has no effect on coagulation parameters, and can be administered by oral and intravenous methods. Some studies have suggested that the mechanism of tranexamic acid in the treatment of melasma includes its changes on the dermal pathological changes of melasma; tranexamic acid is a fibrinolytic enzyme inhibitor, which can inhibit the formation of blood vessels and reduce the number of erythema and blood vessels; tranexamic acid can also reduce the number of mast cells and inhibit the activity of mast cells. Studies have shown that oral tranexamic acid has good efficacy when given to patients with melasma, but the required course of treatment is longer, the adverse effects are mild, the use is safer and the recurrence rate is lower. Some authors observed the efficacy of applying intravenous drip and oral tranexamic acid in treating patients with melasma, and the results showed that the intravenous group had a faster onset of action than the oral group. III. Systematic treatment of chloasma with tranexamic acid combined with laser There are several kinds of lasers that can treat chloasma, and some patients can achieve good efficacy through the combination of different lasers and photons. At the same time, people also try to combine laser and drugs to improve the efficacy, and tranexamic acid has become a new choice. It has been found that large spot low energy 1 064 nm laser is effective in treating melasma, and the combination with oral tranexamic acid is more effective. Tranexamic acid is effective in small oral doses and can be used alone or in combination with other oral and topical medications and lasers. There is a significant difference between the duration of medication and the efficacy, generally 1 to 2 months after medication, the longer the treatment time, the better the efficacy. The safety of tranexamic acid is good. The common adverse reactions are mainly gastrointestinal reactions, such as nausea, vomiting and diarrhea, and decreased menstrual flow. IV. Topical topical tranexamic acid for melasma One study showed that clinical improvement was obtained in both tranexamic acid and excipient groups, but the difference between the two groups was not statistically significant. As for adverse reactions, erythema occurred in some patients with topical tranexamic acid 5%. It is suggested that topical tranexamic acid may be similar to excipients in improving the lesions and did not play a therapeutic role. However, it has been reported that simultaneous administration of systemic and topical tranexamic acid would be superior to systemic administration alone. V. Microneedle and microinjection of tranexamic acid for melasma Some scholars included 100 female patients with melasma, and after local anesthesia, tranexamic acid was injected by microinjection, as a result, 85 patients completed the treatment, and 9.4% of them obtained significant improvement, 76.5% obtained general improvement, and 14.1% obtained slight improvement. The authors concluded that intra-local lesion injections of tranexamic acid are a promising approach for the treatment of melasma. The study showed that both microneedle and microinjection of tranexamic acid were effective, with the former being more effective and with minimal adverse effects.