Tranexamic acid in skincare — what it does and how to use it.

Tranexamic acid arrived in skincare from pharmaceutical use — it is a synthetic derivative of the amino acid lysine, developed as an antifibrinolytic agent used in surgical and emergency medicine contexts. Its repurposing in topical skincare grew from observations that patients using it for other reasons experienced reduced pigmentation, which prompted investigation into its mechanism in skin.

That mechanism turns out to be distinct from virtually every other brightening active in common use.

How it works

Most brightening ingredients target the melanogenesis pathway at one of a small number of well-understood steps. Vitamin C and kojic acid inhibit tyrosinase, the enzyme that catalyses the first committed step of melanin synthesis. Niacinamide blocks the transfer of melanosomes from melanocytes to surrounding keratinocytes. Azelaic acid combines tyrosinase inhibition with selective cytotoxicity on hyperactive melanocytes.

Tranexamic acid works through a different mechanism: it blocks plasmin-driven signalling between keratinocytes and melanocytes. UV exposure causes keratinocytes to produce plasminogen activator, which activates plasmin, which stimulates melanocytes via prostaglandin and cytokine signalling to increase melanin production. Tranexamic acid interrupts this upstream communication pathway before melanogenesis is stimulated.

This is not a minor distinction. Because it targets a different step in a different pathway, tranexamic acid is genuinely additive when used alongside vitamin C, niacinamide, or azelaic acid — not redundant or duplicative. Combining them addresses melanogenesis at multiple distinct points.

The evidence

The clinical evidence for tranexamic acid in pigmentation is strongest for melasma — a hormonally driven, UV-exacerbated condition that is among the most difficult pigmentation types to treat. Several randomised controlled trials have shown topical tranexamic acid at 2–5% to be comparable in efficacy to kojic acid and, in some studies, to low-dose topical hydroquinone, with better tolerability in both cases.

Evidence for post-inflammatory hyperpigmentation and general skin tone irregularity is less extensive but consistent with its mechanism — it should reduce any melanogenesis driven by the UV and inflammatory signalling pathway it targets.

Concentration and formulation

Effective topical concentrations in the clinical literature sit at 2–5%. Unlike vitamin C, tranexamic acid is stable in aqueous formulations without requiring a low pH for activity. This gives it formulation flexibility — it can be combined in serums alongside niacinamide or other water-based actives without the pH conflicts that arise when layering vitamin C with certain ingredients.

It is not a photosensitiser. It can be used morning or evening. There is no established reason to limit it to PM use.

Where it fits in a routine

Tranexamic acid fits naturally in the treatment step: water-based, after cleansing, before moisturiser. It can be formulated alongside niacinamide for combined downstream and upstream blockade of melanogenesis, or used as a standalone in a simple three-step routine without other actives competing for efficacy or causing interaction.

The most common context for adding it is when a general brightening or anti-PIH routine — already using niacinamide and vitamin C — needs further support, particularly for melasma or stubborn hyperpigmentation that has not fully responded after an appropriate trial period.

What it does not do

Tranexamic acid addresses melanogenesis. It does not affect structural dark circles (which have no topical treatment), dullness from dead-cell accumulation (which requires exfoliation), or the vascular component of dark circles. It does not function as an exfoliant or a barrier ingredient.

It is also not a substitute for sun protection. UV is the primary driver of the plasmin signalling it interrupts — and UV exposure continues regardless of what is applied topically. Daily broad-spectrum SPF is the prerequisite for any brightening intervention to hold its results over time.

The L&G context

The niacinamide in the Lux & Glo serum addresses the downstream transfer of melanosomes to surrounding skin cells — the step that determines whether pigment actually reaches the skin surface. Tranexamic acid addresses the upstream stimulation of melanocytes before they produce melanin. Used together, they act at different control points in the same process. This is the logic behind additive active selection: not more of the same, but different mechanisms covering different ground.