Melasma and peptides: what lightens, what darkens and what is proven

A common problem in Latin American skin

Melasma is a chronic, relapsing hyperpigmentation of sun-exposed areas, most frequent in adult women with darker phototypes. Its main drivers are sun exposure, sex hormones (pregnancy, for example) and genetic predisposition². A consensus of nine Latin American experts describes it as highly prevalent in the region, where many countries lie in the intertropical zone and the population reflects centuries of mixing among Native Americans, Europeans and Sub-Saharan Africans². The Latin American Pigmentary Disorders Academy estimated a prevalence of up to 10% of the Latin American population¹.

For the dermatologist, plastic surgeon and aesthetic physician in Panama, this means a daily consultation and a recurring question: whether peptides, so present today in the conversation about skin, have a place in treatment.

What lies behind the patch

The classic view of melasma centers on the overactive melanocyte and on tyrosinase, the enzyme responsible for melanin overproduction⁷. Recent reviews widen the focus to the dermis: basement-membrane changes, solar elastosis, mast cells, vascular changes, senescent fibroblasts and the effect of visible light and hormonal fluctuations³. A 2026 review proposes viewing melasma as persistent melanocyte activation sustained by a photoaged dermis, in which senescent fibroblasts, UV-activated sebocytes and vascular components send continuous melanogenic signals; according to the authors, this would explain its midlife onset, its relapsing course and its attenuation later in life⁴.

In that cascade the melanocortin 1 receptor (MC1R) is central: its activation increases eumelanin production⁵. That fact explains why an entire family of peptides does the opposite of what a melasma patient wants.

Melanocortins: the peptides that darken

Afamelanotide is an MC1R agonist approved by the FDA in 2019, as a 16 mg subcutaneous implant, to increase pain-free light exposure in adults with a history of phototoxic reactions from erythropoietic protoporphyria⁵. In the two randomized placebo-controlled trials behind it (74 patients in Europe and 94 in the United States), pain-free direct sun exposure was longer with afamelanotide: median 69.4 versus 40.8 hours in the U.S. study (P = 0.04) and 6.0 versus 0.8 hours in the European one (P = 0.005), with fewer phototoxic reactions (77 versus 146)⁶.

Its label explains the mechanism: afamelanotide increases eumelanin production in the skin independently of sun exposure, and it warns that it «May induce darkening of pre-existing nevi and ephelides», recommending a full-body skin examination twice a year⁵. It is an example of an approved, effective peptide whose effect is pigmenting. The same holds, without approval or quality control, for melanotan, whose history and risks are reviewed in Melanotan II and PT-141. In a melasma patient, an α-MSH analogue goes in the opposite direction.

Tyrosinase-inhibiting peptides: what the trials show

At the other end are topical oligopeptides designed to slow melanogenesis. The best studied is a proprietary oligopeptide, sold as Lumixyl and described as decapeptide-12 in later studies, which competitively inhibited mushroom and human tyrosinase without the toxicity associated with hydroquinone⁷⁸. In a randomized, double-blind, placebo-controlled split-face pilot, five women of phototype IV with moderate recalcitrant melasma applied it at 0.01% for 16 weeks; all five showed statistically significant improvement, with no visible irritation or allergy⁷.

The most useful data point for Panama is a prospective, open-label, multicenter study in 33 Hispanic women with mild to moderate melasma. With a regimen of 0.01% decapeptide-12, an antioxidant cleanser, 20% buffered glycolic acid and SPF 30 sunscreen, mean MASI fell 36%, 46%, 54% and 60% at weeks 4, 8, 12 and 16, with no adverse events reported⁸.

With oligopeptide-68, a TGF-β1 biomimetic that inhibits tyrosinase, a 12-week randomized double-blind trial in 40 women (38 completed) combined the peptide with diacetyl boldine and sunscreen; melasma improved from baseline at weeks 6 and 12 (P < 0.05) and 76.3% of participants rated their improvement as moderate⁹. Finally, epidermal growth factor, a polypeptide, was tested in a placebo-controlled split-face trial in 15 women: after 8 weeks, GAIS scores showed improvement on 73.4% of treated sides versus 13% of placebo sides¹⁰.

The benchmark: tranexamic acid

Any new melasma active is now compared with tranexamic acid, which is not a peptide but a synthetic lysine analogue, mainly used as an antifibrinolytic¹¹. In a randomized, double-blind, placebo-controlled trial in patients with moderate to severe melasma, mostly Hispanic women, 44 patients received 250 mg twice daily or placebo for 3 months (39 completed); mMASI fell 49% with tranexamic acid versus 18% with placebo, and three months after stopping, the reduction from baseline was 26% versus 19%¹².

A meta-analysis of 22 randomized studies with 1,280 patients confirmed a significant reduction in severity by the oral, topical or injected route, with the largest MASI reduction orally; reported adverse effects were gastrointestinal discomfort, skin irritation and menstrual irregularities, and heterogeneity between studies was high¹³. No anti-pigment peptide currently has a comparable evidence base.

Microneedling and delivery

Microneedling is used to enhance transcutaneous penetration of actives. In a meta-analysis, microneedling plus tranexamic acid was significantly more effective than microneedling alone, although overall it did not outperform other treatments¹⁴. With a tripeptide, glutathione, a split-face study in 29 women with epidermal melasma compared six microneedling sessions with or without glutathione solution: improvement was 55.17% versus 46.92%, a significant difference¹⁵. The oral and intravenous glutathione evidence is reviewed separately in Glutathione for skin lightening. We found no PubMed trials of decapeptide-12 or oligopeptide-68 delivered with microneedling.

Limits of the evidence

• Trials of anti-pigment peptides are small: 5, 15, 33 and 40 participants⁷⁸⁹¹⁰.
• The peptide is almost always part of a combination (glycolic acid, diacetyl boldine, sunscreen), so its own contribution cannot be isolated⁸⁹.
• The study in 33 Hispanic women was open-label with no control group⁸.
• In the oligopeptide-68 trial, the comparison with 2% and 4% hydroquinone was made on normal arm skin, not on melasma⁹.
• Melasma relapses: the Latin American consensus recommends continuing topical depigmenting agents and strict photoprotection after remission²; no peptide study followed patients beyond 16 weeks of treatment⁷⁸⁹¹⁰.