Afamelanotide (Scenesse) is an FDA-approved prescription implant with published safety data. Unregulated "Melanotan I" sold for injection is neither approved nor characterised. This page summarises published safety information and is not medical advice.
Overview
Melanotan I is one of the few compounds in this catalogue whose side effects can be stated with percentages instead of adjectives, because the approved version went through a full drug application. The picture that emerges is a drug with a mild acute profile and one structural concern that outlasts any single dose: it stimulates the exact cell type — the melanocyte — from which melanoma arises, and the approved label handles that with a standing dermatological surveillance requirement rather than a reassurance.
What the label reports, with numbers
Adverse reactions occurring in more than 2% of patients receiving the 16 mg implant (Scenesse label, DailyMed):
- Implant site reaction — 21%, the most common event, and specific to the delivery format rather than the peptide.
- Nausea — 19%, the characteristic melanocortin effect, though far below the 40% seen with the non-selective relative bremelanotide.
- Oropharyngeal pain — 7%; cough — 6%; fatigue — 6%.
- Skin hyperpigmentation — 4%, listed as an adverse reaction, not an intended effect.
- Dizziness — 4% and melanocytic naevus — 4%.
In the pivotal NEJM trials, adverse events were mostly mild and serious adverse events were not judged to be related to the study drug (Langendonk, Balwani et al. 2015). That is a genuinely favourable acute profile, and it is worth stating plainly rather than hedging into vagueness.
The monitoring requirement is part of the safety profile
The label warns that afamelanotide may cause generalised increased skin pigmentation and darkening of pre-existing naevi and ephelides, and it directs that patients receive a full-body skin examination twice yearly to monitor existing and new pigmentary lesions.
That instruction is the most transferable piece of safety information on the page. It exists because a drug that darkens moles can obscure the visual cues clinicians use to detect melanoma early, and because a 4% incidence of new melanocytic naevi is not zero. The requirement is not a formality attached to a rare-disease drug; it is the mechanism by which the drug's known effect is kept from becoming a missed diagnosis.
The photoprotection illusion
Increased pigmentation raises tolerance to light. It does not license unlimited sun exposure, and no trial has tested whether afamelanotide changes skin cancer incidence in either direction. The EPP population studied has a specific reason to want daylight tolerance; a person seeking cosmetic colour is buying the same mechanism without the clinical rationale — and, if they then spend more time in the sun believing they are protected, may increase ultraviolet exposure rather than reduce it.
What changes with an unregulated vial
Every figure above describes a pharmaceutical implant made to a specification. Powder sold as "MT-1" for self-injection differs on four axes at once: identity and purity are unverified, the delivered quantity depends on reconstitution and syringe reading, sterility depends on the buyer's technique, and no clinician is performing the twice-yearly skin examination the approved product requires.
A 2017 review of unregulated α-MSH analogue use catalogued exactly this gap. It notes that afamelanotide has demonstrated safety through rigorous testing while illegal melanotans carry uncertainties about preparation, administration and dosing, documents cutaneous complications including changes to existing moles and emergence of dysplastic naevi, and records four case reports of melanomas arising from existing moles during or shortly after melanotan use — while being careful that causation is not established (Habbema et al., Int J Dermatol 2017). Any new, changing, or darkening pigmented lesion is a reason to see a dermatologist promptly, regardless of what produced it.