Tranexamic acid vs. vitamin C — which fades melasma better?

For melasma, rather than hunting for the "stronger" one, it helps to know that these two work by different routes — then you can pick the one your skin needs. Tranexamic acid quiets the signal (the plasmin pathway) that tells skin to make melanin (Maeda, 2022); vitamin C slows the enzyme that makes it (tyrosinase) and adds antioxidant support (Telang, 2013). For stubborn melasma the evidence leans toward tranexamic acid, while vitamin C is gentler and works across overall tone.

When melasma won't fade, it's tempting to reach for "stronger brightening." But tranexamic acid and vitamin C aim at different points. Knowing that difference is how you tell which one fits your melasma.

How does tranexamic acid fade melasma?

Melasma forms when pigment cells are stimulated again and again. Tranexamic acid blocks one route of that stimulation: it inhibits plasmin activity released by skin cells, dialling down the signals and the inflammatory and vascular mediators that spur melanocytes (Maeda, 2022). That's why the evidence is strongest for melasma, which flares with UV and inflammation. Oral tranexamic acid at low doses over time has lowered melasma scores in several trials, and topical forms are used as an adjunct (Kim & Lim, 2022). Tranexamic acid doesn't erase melanin already made; it quiets the "make more" signal itself.

How does vitamin C work?

Vitamin C (ascorbic acid) takes a different road. It slows tyrosinase, the enzyme that builds melanin, and its antioxidant action eases the oxidative stress UV leaves behind, softening the drift toward darker pigment (Telang, 2013). It's useful not only for one patch but for overall dullness and tone, and it's gentle enough to start with easily. In one trial, 5% vitamin C wasn't as fast as 4% hydroquinone but still worked on melasma — with far less irritation (6% vs. 69%) (Espinal-Perez et al., 2004). Vitamin C slows the pigment-making enzyme while also calming the oxidation UV leaves behind.

So which is better for melasma?

It's hard to call one the winner. For old, stubborn melasma the evidence leans toward tranexamic acid (oral especially, which is prescription territory), while vitamin C is gentler and helps more broadly with tone and photoaging prevention. They aim at different points, so it splits by situation: reach toward tranexamic acid for long-standing melasma, toward vitamin C to even tone on reactive skin. Why different marks behave differently is in types of dark spots and UV. The answer isn't the "stronger" ingredient; it's the one that fits your melasma.

Before reaching for a "stronger" ingredient

Any brightening ingredient is a leaking bucket in front of UV. Without daily sun protection, neither tranexamic acid nor vitamin C can do its part. And rather than stacking both hard at once, picking one and using it steadily for 8 to 12 weeks asks less of your skin and gives a clearer result. How to read brightening ingredients overall is in what actually fades pigment. The first ingredient in melasma care is really sun protection; the rest you add one at a time.

One small step

• Whatever you apply, start with morning sun protection. It's half of melasma care.
• Pick one of tranexamic acid or vitamin C and use it steadily for 8 to 12 weeks. You don't have to stack both hard at once.
• If vitamin C stings, start low and thin in the morning.
• For stubborn, long-standing melasma, ask a dermatologist about options like oral tranexamic acid (prescription).