A double-blind, randomized, split-face controlled trial of 34 female patients with melasma was conducted. All subject were randomized to receive either intradermal tranexamic acid or placebo injection on the right or the left side of their face.

All subject were randomized to receive either 10 mg of intradermal tranexamic acid or placebo injection on the right or the left side of their face.

The primary outcome was improvement of melasma lesions assessed by modified Melasma Area and Severity Index (mMASI) score and mexameter examination which includes Melanin Index (MI) and Erythema Index (EI).

Measurements were done at baseline and every two weeks for twelve weeks. Additionally, side effects of therapy and subjects' satisfactory assessment with patient global assessment (PtGA) were also documented.

Inclusion Criteria:

• aged 18 to 60 years old
• Fitzpatrick skin type IV - V
• diagnosed with melasma

Exclusion Criteria:

• pregnancy and breastfeeding
• use of oral contraceptives within six months
• use of topical or systemic melasma therapy within two weeks
• history of superficial peeling within four weeks
• history of dermabrasion within six months
• use of photosensitizer drugs
• history of thrombosis or currently using antithrombotic or anticoagulant drugs
• history of TA allergy
• experiencing any COVID-19 symptoms

The allocation sequence was generated with a computer by an analyst. The allocation sequence was concealed from the investigators, care provider, outcomes assessor, and subjects.