Comparison

Melanotan 2 vs PT-141

Reviewed 22 October 2026 · How we research

PT-141 was developed from Melanotan 2 after researchers noticed MT-2's effect on sexual arousal. The two are close chemical relatives but have very different regulatory stories.

Melanotan 2 vs PT-141 at a glance

How they work

Melanotan 2

MT-2 is a cyclic, shortened α-MSH analogue that is far more potent and longer-lasting than the natural hormone. It activates several melanocortin receptors: MC1R in skin pigment cells (tanning), MC4R and MC3R in the brain (appetite suppression and sexual arousal). Because it is non-selective, these effects come together — which is why nausea and spontaneous erections were common in the original studies.

PT-141

PT-141 activates melanocortin-4 receptors (and MC3R) in the hypothalamus, pathways involved in sexual motivation. This central action is why it was studied for desire rather than erectile mechanics. It retains some activity at MC1R, which explains the focal skin darkening seen with repeated use.

Side effects compared

Melanotan 2

• Nausea and vomiting, facial flushing, yawning and stretching.
• Spontaneous erections and increased libido.
• Reduced appetite.
• Darkening of existing moles and freckles; new moles. Dermatologists report cases of melanoma in users.
• Rare reports of kidney problems and rhabdomyolysis.

Products bought online have no quality control, adding the risk of contamination and wrong dosing.

PT-141

• Nausea — about 40% in phase 3, usually after the first dose and easing with later doses.
• Flushing, headache, injection-site reactions.
• A transient rise in blood pressure and fall in heart rate after each dose — not recommended with uncontrolled hypertension or heart disease.
• Focal hyperpigmentation (darkening of face, gums, breasts) in about 1% with repeated use.

Bottom line

PT-141 is the more selective, clinically tested molecule with an approved indication in the US. MT-2 remains unlicensed everywhere and is the subject of MHRA warnings.