Melanotan II
Also known as: MT-II, Melanotan 2
Melanotan II (also called MT-II or Melanotan 2) is an unapproved melanocortin agonist. Melanotan II is a cyclic lactam analog of alpha-melanocyte-stimulating hormone and a non-selective agonist across melanocortin receptors, engaging MC1R, MC3R, MC4R and MC5R. MC1R activation on melanocytes drives eumelanin synthesis independently of ultraviolet exposure.
For research use only.
Key Facts
- CAS
- 121062-08-6
- Molecular Weight (MW)
- 1024.2 g/mol
- Half-life
- Not established in humans (no published human pharmacokinetic study)
- FDA status
- Not Approved
- Evidence level
- Limited Human Evidence
- Human dose established
- Yes
- Administration Route
- Subcutaneous
- Frequency
- Single doses on alternating days in the pilot study
- Last updated
- Sep 26, 2026
- Reviewed
- Aug 30, 2026
- Targets
- MC1RMC4RMC3R
Vendor price snapshot
Each vendor counts once, at the median price per mg of its own listings; the typical range is the middle half of vendors. From public vendor listings collected between Dec 2025 and Sep 2026, so confirm the live price on the vendor site. Peptide Library does not sell peptides.
- Vendors listing this peptide
- 33
- Listed offers
- 40
- Median price per mg
- $4.00/mg
- Typical $3.50–$5.38/mg
Research summary
Cyclic α-MSH analog used illicitly for tanning and libido. Not FDA-approved. FDA and EMA have warned against its use. WADA S0 as a non-approved substance.
Peptide Library's Melanotan II profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Melanotan II dosage chart
Melanotan II has been dosed in humans, but only in small studies from the 1990s that investigated erectile function rather than tanning. The published dosing is weight-based: a pilot study started at 0.01 mg/kg subcutaneously and escalated in 0.005 mg/kg steps to a maximum of 0.03 mg/kg. There is no approved product and no modern trial establishing a dose for pigmentation.
| Human dosing established | Yes |
|---|---|
| Studied dose range | 0.01–0.03 mg/kg subcutaneously (weight-based) |
| Route | Subcutaneous |
| Frequency | Single doses on alternating days in the pilot study |
| Duration studied | Short pharmacology studies |
| Titration | Escalated in 0.005 mg/kg increments from a 0.01 mg/kg starting dose in the 1996 pilot study. |
| Evidence level | Limited Human Evidence |
| Last reviewed | 2026-09-05 |
Research-reported dosing
Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| Pilot study (Dorr et al., 1996)Clinical trial · Single-blind placebo-controlled pilot study | Normal male volunteers (n=3) | 0.01 mg/kg starting dose, escalated by 0.005 mg/kg to 0.03 mg/kg in two subjects and 0.025 mg/kg in one | Subcutaneous | Alternating days, saline or MT-II | Single-blind alternating-day protocol | Safety and erectile response | Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996. |
| Psychogenic erectile dysfunction study (1998)Clinical trial · Clinical study | Men with psychogenic erectile dysfunction | 0.025 mg/kg | Subcutaneous | — | — | Erectile response | Wessells H et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998. |
| NCT07437560 — phase 2, recruiting, no resultsClinical trial · Registered phase 2 trial, recruiting | Patients with vitiligo (planned n=60) | Not disclosed | Not disclosed | — | — | Repigmentation as an adjunct to NB-UVB phototherapy | NCT07437560 — Melanotan II (MT-II) as an Adjunct to NB-UVB Phototherapy for Repigmentation |
Where sources disagree
- Published human dosing is weight-based and small: 0.01–0.03 mg/kg, which is roughly 0.7–2.1 mg for a 70 kg adult. Fixed protocols of 0.25–1 mg daily published elsewhere are not derived from these studies and have no primary source.
- Every published human study of melanotan II examined erectile function, not tanning. The pigmentation use it is overwhelmingly sold for has no completed trial behind it; the only registered pigmentation trial is in vitiligo and is still recruiting.
- Melanotan II is unlicensed and its sale for human use is prohibited in several jurisdictions, including by the UK MHRA. This profile reports what was studied, not what is lawful or advisable.
Reconstitution
Common research vial sizes: 10 mg.
| Vial | Bacteriostatic water | Concentration | Per 0.01 mL |
|---|---|---|---|
| 10 mg | 2 mL | 5 mg/mL | 50 mcg per 0.01 mL |
These figures are arithmetic only — they convert a vial and a volume into a concentration. They are not a recommendation to take any dose.
Calculate reconstitution & dose →Handling & administration
- Reconstitution Guide
- Add 2 mL bacteriostatic water per 10 mg vial.
- Injection Sites
- AbdomenThigh
- Concentration Example
- 10 mg + 2 mL → 5 mg/mL
- Timing Notes
- Evening injections to minimize side effects
- Expected Onset
- 3–7 days
How to reconstitute Melanotan II
- Check the vial size and diluent volume. The profile example for Melanotan II is: Add 2 mL bacteriostatic water per 10 mg vial.
- Swab both vial stoppers and draw the bacteriostatic water into a sterile syringe.
- Add the water slowly down the inside wall of the peptide vial so it does not jet onto the powder, then swirl gently until the solution is clear. Do not shake.
- Record the resulting concentration: 10 mg + 2 mL → 5 mg/mL.
- Label the vial with the date and concentration, refrigerate it (see Storage & stability below), and use the calculator preset to convert a dose in mcg into syringe units.
Sequence & molecular data
| Molecular formula | C50H69N15O9 |
|---|---|
| Molecular weight | 1024.2 g/mol |
| CAS number | 121062-08-6 |
| Half-life | Not established in humans (no published human pharmacokinetic study) |
| Appearance | White to off-white lyophilized powder |
| Formulation | Lyophilized Powder |
| PubChem CID | 92432 |
| FDA UNII | UPF5CJ93X7 |
| ChEMBL | CHEMBL430239 |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
Melanotan II is a cyclic lactam analog of alpha-melanocyte-stimulating hormone and a non-selective agonist across melanocortin receptors, engaging MC1R, MC3R, MC4R and MC5R. MC1R activation on melanocytes drives eumelanin synthesis independently of ultraviolet exposure. MC4R activation in the hypothalamus accounts for the appetite suppression and, through spinal and central pathways, the sexual arousal effects reported with it — the observation that led to the development of bremelanotide, which was derived from it. That lack of receptor selectivity is the source of its side-effect profile, including nausea, flushing and darkening of existing naevi. It is not approved anywhere and is sold only as a research chemical.
Origin
Synthetic cyclic lactam α-MSH analog.
Targets
Studies
- 5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II
- Melanotan-II reverses memory impairment induced by a short-term HF diet
- CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists
- Melanotan II, a melanocortin agonist, partially rescues the impaired thermogenic capacity of pituitary adenylate cyclase-activating polypeptide deficient mice
- Melanotan II User Experience: A Qualitative Study of Online Discussion Forums
Regulatory & research status
Melanotan II is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Availability | Research-Only |
| WADA (sport) | Banned in Sport |
| Library classification | Research-Only |
Benefits
Melanotan II side effects
Melanotan II has only limited human data, so the list below is incomplete and its side-effect profile is not well established.
Side Effects
- Nausea
- Flushing
- Spontaneous erections
- New moles
- Hypertension
Contraindications
- Avoid if prone to moles
- Not recommended with heart conditions
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Cosmetic peptides in this library are formulated into topical products; follow the product label rather than the reconstitution guidance above.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
Melanotan II: frequently asked questions
What is Melanotan II?
Cyclic α-MSH analog used illicitly for tanning and libido. Not FDA-approved. FDA and EMA have warned against its use. WADA S0 as a non-approved substance.
How does Melanotan II work?
Melanotan II is a cyclic lactam analog of alpha-melanocyte-stimulating hormone and a non-selective agonist across melanocortin receptors, engaging MC1R, MC3R, MC4R and MC5R. MC1R activation on melanocytes drives eumelanin synthesis independently of ultraviolet exposure.
Is Melanotan II FDA approved?
No. Melanotan II is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use.
What is the half-life of Melanotan II?
No human half-life has been published for Melanotan II. The pharmacokinetic studies indexed in PubMed were in rats and mice, where it cleared rapidly from plasma. Figures quoted by vendors and forums have no published human study behind them.
Is Melanotan II banned in sport?
Melanotan II is recorded here as prohibited in sport. Athletes subject to anti-doping rules should check the current WADA Prohibited List directly, since it is revised annually and classifications change.
What peptides are similar to Melanotan II?
Compounds most often compared with Melanotan II include Afamelanotide, Bremelanotide, Setmelanotide and KPV. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- WADA Prohibited List 2026External reference
- 5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II — Chemistry, 2024External reference
- Melanotan-II reverses memory impairment induced by a short-term HF diet — Biomed Pharmacother, 2023External reference
- CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists — J Med Chem, 2022External reference
- Melanotan II, a melanocortin agonist, partially rescues the impaired thermogenic capacity of pituitary adenylate cyclase-activating polypeptide deficient mice — Exp Physiol, 2021External reference
- Melanotan II User Experience: A Qualitative Study of Online Discussion Forums — Dermatology, 2021External reference
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Sep 26, 2026 · Version 3
This Melanotan II profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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