Oral tranexamic acid has been used for years to help enhance blood clotting. Serendipitously, it was found to also improve hyperpigmentation. Today it can be applied in a topical form for hyperpigmentation, avoiding the oral route (and related side effects) altogether.
Tranexamic acid targets melanin production, and thereby visibly fades multiple types of discoloration, from acne-induced post-inflammatory hyperpigmentation (PIH), to melasma. It does not exfoliate or stimulate collagen, so it is typically combined with other medications.
Most people will notice results with consistent use in 8-12 weeks