Peptide Academy · Libido

Melanotan II (MT-II)

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Educational research summary, not medical advice. Many compounds here are not approved for human use. Talk to a licensed clinician before making any health decision.

The Peptide Academy is free to read. Members also get the research protocols for Melanotan II (MT-II), dose and vial tracking, and an AI Advisor with cited sources. Try it all free for 7 days, no card needed.

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What is Melanotan II (MT-II)?

Melanotan II is a synthetic analog of alpha-MSH that non-selectively activates melanocortin receptors (MC1R through MC5R). Its sexual effects stem primarily from MC3R and MC4R activation in the hypothalamus and limbic system, producing powerful and spontaneous arousal, erections, and sexual motivation — often more potent than its successor PT-141. It also activates MC1R in melanocytes, producing a tanning effect without UV exposure. Originally developed as a potential tanning agent, its strong pro-erectile and libido-enhancing effects led to significant research interest. While PT-141 (Bremelanotide) was developed as a more selective and better-tolerated derivative, MT-II remains in use for its particularly strong sexual effects, though it carries a higher side effect burden.

What it has been studied for

  • Potent stimulation of sexual arousal and spontaneous erections
  • Acts centrally via melanocortin receptors — independent of vascular function
  • Can be effective where PDE5 inhibitors fail or are contraindicated
  • Produces skin tanning via MC1R activation
  • Strong pro-erectile effects in men
  • May increase sexual motivation in women
  • Faster onset than many sexual health peptides

These are effects reported or investigated in research, much of it preclinical. They are not proven outcomes or health claims.

Half-life

~1–2 hours

Cautions

Educational content only. Not medical advice. Consult a licensed physician before use.

Side effects & fixes

Common side effects

  • —Nausea — the most common effect, usually in the first doses
  • —Facial flushing
  • —Spontaneous erections (Melanotan II)
  • —Darker freckles and moles, and skin tanning
  • —Reduced appetite and frequent yawning
  • —Temporary rise in blood pressure (PT-141)

Histamine reactions

Common flushing and warmth across the face and neck shortly after dosing.

Common fixes

  • Start with a very small dose and increase gradually; nausea fades as you adapt.
  • Dose a few hours after a light meal, and keep ginger or bland snacks on hand.
  • Avoid if you have uncontrolled high blood pressure or heart disease.
  • Check your moles regularly and have any that change looked at by a dermatologist.
  • For mild itching, redness or flushing, a non-drowsy over-the-counter antihistamine (such as cetirizine or loratadine) is commonly used — check with a pharmacist first, especially if you take other medicines.

Stop and get help

  • A painful erection lasting more than 4 hours.
  • Any mole that changes shape, colour or size.
  • Stop and get emergency help for swelling of the face, lips, tongue or throat, trouble breathing, widespread hives, chest pain or fainting.

Basis: Prescribing information (bremelanotide) and clinical reports for melanocortins. Educational only, not medical advice.

Medication concerns

Theoretical: no human interaction studies

  • Blood pressure medicines, heart disease

    Melanocortin agonists can raise blood pressure and change heart rate after a dose.

  • Erectile dysfunction pills (sildenafil, tadalafil)

    Combining with melanotan II or similar may raise the risk of prolonged, painful erections. An erection over 4 hours is an emergency.

  • Medicines taken by mouth

    Some melanocortin drugs slow stomach emptying, which can delay absorption.

  • Photosensitizing medicines (doxycycline, isotretinoin) and skin cancer risk

    Tanning agents darken skin and moles; have new or changing moles checked.

  • Everything else you take, including supplements

    Bring a full list of medicines and supplements to your pharmacist or clinician before starting.

Basis: Extrapolated from bremelanotide and setmelanotide labels; no interaction studies for research melanocortin peptides. Educational only, not medical advice. Never stop or change a prescribed medicine without your prescriber.

Protocols & tracking are members-only

Members see the research protocols for Melanotan II (MT-II), plan schedules, track every dose and vial, and ask the AI Advisor questions with cited sources. Try every Researcher feature free for 7 days, no card needed.

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