How Do Tranexamic Acid Tablets Work to Treat Melasma?

This is a great question! If you have ever suffered from heavy periods, you may have taken tranexamic acid (TXA) to lighten your period because it works to stop the breakdown of a protein called fibrin and fibrin is one of the main components of a blood clot. Hence, TXA reduces blood flow.

It was first used in the treatment of melasma in 1979 (Nijor). Here is a step-by-step explanation of how we think TXA works to lighten melasma (Maeda + Tomita, 2007):
Plasmin found in keratinocytes (skin cells) induces the production of both arachidonic acid and alpha-melanocyte-stimulating hormone
Arachidonic acid and alpha-melanocyte-stimulating hormone stimulate the production of melanin (skin pigment) by melanocytes, which can lead to melasma
Plasminogen activator is required to make plasmin do what it does in the keratinocytes

Plasminogen activator has lysine-binding sites on it – these sites need to be stimulated to activate the activator to then go on to get plasmin to do its thing
TXA is a synthetic derivative of the amino acid lysine – it looks like lysine – so it can bind to the plasminogen activator site instead of lysine and therefore block it from activating it in the first place.

There have been 2 good quality, well-designed randomised controlled trials comparing the use of TXA 500 mg daily vs placebo (and both groups using topical hydroquinone) over 8 and 12 weeks (300 patients total). Both studies showed a statistically significant improvement in melasma in the TXA group vs the placebo group. Importantly, no patients reported any adverse events from the TXA requiring the treatment to be stopped (Padhi et al 2015, Karn et al 2012).

Bottom line: TXA can be an effective addition to your topical melasma treatment and the clinical trial evidence supports this. Talk to your doctor about whether or not it is right for you.