Melasma and Skin Hyperpigmentation: Evidence-Based Causes and Treatment

Melasma (formerly also called chloasma) is an acquired, chronic pigmentation disorder that shows up as symmetrical, brown or grayish-brown patches, most often on the cheeks, forehead, nose, upper lip, and chin — the areas most exposed to the sun. It affects women far more often than men, and it tends to be more severe and persistent in people with darker skin phototypes than in those with fair skin.

A key feature of melasma, one that sets it apart from many other forms of hyperpigmentation, is its layered, chronic nature: excess melanin production doesn't just affect the superficial layer of the epidermis — in many cases it reaches into the dermis as well, which makes treatment harder and explains why the patches so easily come back even after apparently successful therapy.

The mechanism linking these factors centers on excessive activation of melanocytes — the cells that produce melanin — under the influence of UV radiation and sex hormones, leading to increased pigment deposition in the epidermis and, in many cases, in the dermis as well. Affected skin also shows increased vascularization (growth of small blood vessels), which partly explains why some therapies targeting only the pigment itself don't always give a complete result.

In melasma, protection against visible light matters just as much as UV protection — in people with darker skin phototypes, mineral sunscreens containing iron oxide (beyond plain zinc oxide and titanium dioxide) have shown additional effectiveness in studies at reducing recurrence, because they also block part of the visible light spectrum that classic UV filters don't always fully address.

Topical hydroquinone works by inhibiting tyrosinase — a key enzyme in the melanin production pathway. It's effective, but needs to be used under supervision, since improper, overly prolonged use (particularly at the high concentrations available over the counter in some countries) carries a risk of exogenous ochronosis — a paradoxical, hard-to-treat dark discoloration. In clinical practice it's typically used cyclically, for limited periods, often combined with tretinoin and a mild corticosteroid in a triple formula.

Tranexamic acid, long known as a drug that inhibits bleeding, has over the last decade earned a place in melasma treatment thanks to its effect of reducing vascularization and melanocyte activity in affected skin. It can be used topically, orally, or as intradermal injections — with a growing number of studies comparing these forms with classic hydroquinone, suggesting comparable or, in some protocols, even slightly higher effectiveness for topical and intradermal tranexamic acid, with a lower risk of irritation.

Melasma is one of those skin conditions where enthusiasm for new, aggressive treatments easily leads to worse outcomes than consistently sticking to the basics. The best-documented therapies — hydroquinone, tranexamic acid, azelaic acid — work for real, but only combined with rigorous, year-round sun protection, without which the effect of any of them is temporary.