Overview
Overview
Melanotan II is a synthetic analog of α-melanocyte-stimulating hormone studied for its ability to increase skin pigmentation and noted for inducing erectile activity as a side effect[1]. Early human trials identified effective daily doses in the range of 1–2 mg for tanning, with conservative protocols starting lower to minimize side effects such as nausea and flushing[2][3]. This educational protocol presents a once-daily subcutaneous titration approach using practical dilution for clear insulin
- Category
- Sexual Health
- Routes
- subcutaneous
Mechanism
Melanotan II
Mechanism of action
Mechanism of action
Melanotan 2 works by turning on a family of receptors in your body called melanocortin receptors. These receptors sit on different cells and control different things: skin pigment, hunger, sexual signaling, and more. Most modern drugs are designed to hit only one receptor. MT-2 hits several at once. That is why it produces several effects at the same time - and also more observed effects than newer, targeted versions. MC1R sits on the pigment-making cells in your skin. When MT-2 turns it on, those cells make more melanin, which is the natural brown pigment that darkens skin. MC3R and MC4R sit in the brain and control sexual arousal. This is a brain-level effect, not a blood-flow effect like Viagra. The same brain receptors involved in arousal also help control hunger. Many users report less appetite while loading. MC5R sits mostly in glands. It is less linked to obvious effects but may add to the overall observed effect picture. Because MT-2 turns on all of these receptors at once, researchers later built more focused versions. Afamelanotide mostly hits MC1R and is FDA-approved for a rare skin condition called erythropoietic protoporphyria. Bremelanotide (PT-141) mostly hits MC3R/MC4R and is FDA-approved for low sexual desire in women.
Key research findings
- 01
Melanotan II is a synthetic cyclic analog of alpha-melanocyte-stimulating hormone (alpha-MSH) and a non-selective melanocortin receptor agonist; an early Phase I human study reported increased skin pigmentation after subcutaneous administration (human study; Dorr et al., Life Sciences, 1996).
- 02
The same University of Arizona research program observed spontaneous penile erections and increased reported sexual desire in male participants, attributed to central melanocortin (notably MC4R) activity (human studies; Dorr et al., 1996; Wessells et al., Int J Impot Res, 2000).
- 03
A double-blind, placebo-controlled crossover study in men with erectile dysfunction reported that Melanotan II initiated erections in the absence of sexual stimulation, with nausea and yawning among the observed effects in research (human study; Wessells et al., 2000).
- 04
Melanotan II served as the structural starting point for the more receptor-selective analog bremelanotide (PT-141) (medicinal chemistry / preclinical development).
- 05
Preclinical in vitro and animal studies characterize its broad melanocortin activity across pigmentary (MC1R) and central (MC3R/MC4R) pathways (in vitro and animal models).
Primary source: Dorr et al. 1996 - Phase I, healthy volunteers: Showed clear pigmentation gains with frequent nausea and spontaneous erections at studied doses. Wessells et al. 1998 - Phase II, psychogenic ED: Placebo-controlled study reporting strong erection-response signals in most treated participants. Wessells et al. 2000 (Urology) - Phase II, organic ED: Reported better erection response and rigidity time vs. placebo in men with organic ED. Wessells et al. 2000 (combined) - mixed ED: Combined analysis showing higher sexual desire and robust erection frequency, with notable nausea rates. Dorr et al. 2004 - Phase I, MT-2 plus UV: MT-2 combined with brief UV exposure produced stronger tanning than UV alone in healthy volunteers. Minakova et al. 2019 - preclinical mouse model: Animal study suggesting MT-2 may affect social behavior through MC4R-oxytocin signaling. Not human evidence.
Pharmacokinetic profile
Single-dose plasma curve over 24h. Shaded band = commonly-cited therapeutic window. Illustrative only.
Protocol Reference
Protocol reference
Commonly cited research range: 500–1000 mcg, twice_weekly.
Reference figures reported in the research literature — not a dosing recommendation. For interactive vial math and scheduling, see the Calculator and Schedule tabs.
Cited protocol & reconstitution guide
Source-backed reference fields by phase, including any volume fields authored in the cited guide.
Days 1–3 (Assessment)
100–250 mcg daily
Days 4–14 (Low loading)
250–500 mcg daily
Weeks 3–6 (Standard loading)
500–1000 mcg daily
Maintenance (Standard)
500–1000 mcg, 1–2× per week
Maintenance (Light)
250–500 mcg, 1× per week or less
| Phase | Reference amount | Units / volume |
|---|---|---|
| Days 1–3 (Assessment) | 100–250 mcg daily | 2–5 units (0.02–0.05 mL) |
| Days 4–14 (Low loading) | 250–500 mcg daily | 5–10 units (0.05–0.10 mL) |
| Weeks 3–6 (Standard loading) | 500–1000 mcg daily | 10–20 units (0.10–0.20 mL) |
| Maintenance (Standard) | 500–1000 mcg, 1–2× per week | 10–20 units (0.10–0.20 mL) |
| Maintenance (Light) | 250–500 mcg, 1× per week or less | 5–10 units (0.05–0.10 mL) |
Titration protocol
- Days 1–3 (Assessment)Start100–250 mcg daily
Bedtime dosing commonly used so peak nausea happens during sleep.
- Days 4–14 (Low loading)Build250–500 mcg daily
Step up only if side effects stay manageable.
- Weeks 3–6 (Standard loading)Build500–1000 mcg daily
Continued until target pigment is reached; brief UV exposure is often coordinated. Loading is commonly capped at 8 weeks.
- Maintenance (Standard)Build500–1000 mcg
1–2× per week. Missed dose: skip it and return to the regular schedule.
- Maintenance (Light)Maintenance250–500 mcg
1× per week or less; common when pigment is already strong and UV exposure is regular.
Storage & Handling
Storage requirements(typical for most peptides)
Can be stored for extended periods. Protect from moisture.
Store in refrigerator door. Never freeze after reconstitution.
Label vials with reconstitution date. Discard if cloudy.
Reconstitution steps
- 01🌡️Wipe the stoppers: fresh alcohol swab on the MT-2 vial stopper and the BAC water vial stopper.
- 02🧴Draw 2 mL bacteriostatic water into a sterile syringe — this 10 mg vial yields 5 mg/mL.
- 03💉Inject against the side wall of the vial, not directly onto the powder.
- 04💧Let it dissolve on its own; gently swirl if needed, do not shake hard.
- 05🔄Check the solution: should be clear and colorless; do not use if cloudy or particulate.
- 06🏷️Refrigerate at 35.6–46.4 °F (2–8 °C); keep out of direct light.
- 07❄️Important: This guide is for educational purposes only and is not medical advice. Melanotan II is not an approved medication. For research use only.
Additional storage notes
Store at −20 °C (−4 °F) or below in dry, dark conditions; keep desiccated to minimize moisture exposure [7] .
Refrigerate at 2–8 °C (35.6–46.4 °F); use within 1–2 weeks with bacteriostatic water preservative [7] .
Do not refreeze reconstituted solution; prepare aliquots if longer storage needed.
Allow vials to reach room temperature before opening to reduce condensation.
Clinical Evidence
Clinical evidence
Research describes increased melanogenesis and melanocortin-mediated activity, with data from early human and animal studies.
Dorr et al. 1996 - Phase I, healthy volunteers: Showed clear pigmentation gains with frequent nausea and spontaneous erections at studied doses. Wessells et al. 1998 - Phase II, psychogenic ED: Placebo-controlled study reporting strong erection-response signals in most treated participants. Wessells et al. 2000 (Urology) - Phase II, organic ED: Reported better erection response and rigidity time vs. placebo in men with organic ED. Wessells et al. 2000 (combined) - mixed ED: Combined analysis showing higher sexual desire and robust erection frequency, with notable nausea rates. Dorr et al. 2004 - Phase I, MT-2 plus UV: MT-2 combined with brief UV exposure produced stronger tanning than UV alone in healthy volunteers. Minakova et al. 2019 - preclinical mouse model: Animal study suggesting MT-2 may affect social behavior through MC4R-oxytocin signaling. Not human evidence.
- 01Melanotan II is a synthetic cyclic analog of alpha-melanocyte-stimulating hormone (alpha-MSH) and a non-selective melanocortin receptor agonist; an early Phase I human study reported increased skin pigmentation after subcutaneous administration (human study; Dorr et al., Life Sciences, 1996).
- 02The same University of Arizona research program observed spontaneous penile erections and increased reported sexual desire in male participants, attributed to central melanocortin (notably MC4R) activity (human studies; Dorr et al., 1996; Wessells et al., Int J Impot Res, 2000).
- 03A double-blind, placebo-controlled crossover study in men with erectile dysfunction reported that Melanotan II initiated erections in the absence of sexual stimulation, with nausea and yawning among the observed effects in research (human study; Wessells et al., 2000).
- 04Melanotan II served as the structural starting point for the more receptor-selective analog bremelanotide (PT-141) (medicinal chemistry / preclinical development).
- 05Preclinical in vitro and animal studies characterize its broad melanocortin activity across pigmentary (MC1R) and central (MC3R/MC4R) pathways (in vitro and animal models).
Evidence maturity varies by compound; much peptide research is preclinical (in vitro or animal-model). Where human data are limited, findings should be read as research observations, not clinical conclusions.
References
Literature references
Published research articles and sources related to Melanotan II.
- 01Dorr RT, Lines R, Levine N, et al. Evaluation of Melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences (1996)et al. (1996)
- 02Wessells H, Fuciarelli K, Hansen J, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction. Journal of Urology (1998)et al. (1998)
- 03Wessells H, Gralnek D, Dorr R, et al. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology (2000)et al. (2000)
- 04Wessells H, Levine N, Hadley ME, et al. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. International Journal of Impotence Research (2000)et al. (2000)
- 05Dorr RT, Ertl GA, Levine N, et al. Effects of a superpotent melanotropic peptide in combination with solar UV radiation on tanning of the skin in human volunteers. Archives of Dermatology (2004)et al. (2004)
- 06Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clinical Toxicology (2012)et al. (2012)
- 07Hjuler KF, Lorentzen HF. Melanoma associated with the use of melanotan-II. Dermatology (2014)et al. (2014)
- 08Schulze F, Erdmann H, Hardkop LH, et al. Eruptive naevi and darkening of pre-existing naevi 24 h after a single mono-dose injection of melanotan II. European Journal of Dermatology (2014)et al. (2014)
- 09Mallory CW, Lopategui DM, Cordon BH. Melanotan tanning injection: a rare cause of priapism. Sexual Medicine (2021)et al. (2021)
- 10Habbema L, Halk AB, Neumann M, Bergman W. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues. International Journal of Dermatology (2017)et al. (2017)
- 11Minakova E, Lang J, Medel-Matus JS, et al. Melanotan-II reverses autistic features in a maternal immune activation mouse model of autism. Translational Psychiatry (2019)et al. (2019)
- 12Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides (2006)et al. (2006)
- 13Wikipedia contributors. Melanotan II. Wikipedia, The Free Encyclopedia (2026)et al. (2026)
Observed Effects
Observed effects in cited research
Common: nausea and flushing
- Nausea is the most common reason people slow down or stop. Flushing (a warm, red feeling in the face and chest) is also frequent. Both tend to ease over the first 1-2 weeks of dosing.
Common: appetite changes, fatigue, yawning
- Many users report eating less, feeling sleepy, or yawning soon after a dose. These are linked to the same melanocortin pathways that affect the brain.
Sexual: spontaneous erections and increased desire
- Trial data show MT-2 can cause unplanned erections and higher sexual desire. This is a brain-signaling effect, not a blood-flow drug like Viagra.
Dermatologic: darkening moles and new moles
- MT-2 can darken existing moles, freckles, and other spots. Case reports describe new moles appearing and rapid changes in old ones after only one or two doses. Because mole changes can sometimes signal melanoma (a serious skin cancer), close monitoring is important.
Serious: priapism
- A few case reports describe priapism, which is a painful, lasting erection. It is a medical emergency and needs urgent care.
Serious: rhabdomyolysis at overdose levels
- Overdose case reports describe rhabdomyolysis, which is when muscle tissue breaks down and can harm the kidneys. These cases involved doses far above typical research-planning ranges.
Watch your moles closely
- Photograph your moles before starting and every few weeks during use. If any mole changes shape, color, size, or starts to bleed, stop dosing and see a dermatologist.
Research Considerations
Research considerations
Research Use Only - not for human or veterinary therapeutic use. Human evidence is limited to early or small studies. Consult a licensed healthcare professional for any clinical decisions.
- MT-2 is a research compound. It is not approved for any medical use. People typically researching it are interested in tanning response, melanocortin signaling, or appetite/sexual function research. Personal use carries real risk and should involve a clinician.
- The groups below have higher risk and are usually flagged in case reports and clinical commentary.
- Case reports have linked MT-2 use to mole changes and melanoma diagnoses. People with prior skin cancer or strong family history should avoid it.
- MT-2 darkens existing moles and can trigger new ones. Anyone with lots of moles or atypical (dysplastic) moles is at higher risk of missing a real warning sign.
- Flushing, blood pressure changes, and rare reports of more serious events suggest people with uncontrolled cardiovascular disease should avoid use.
- Case reports include priapism, which is a prolonged, painful erection that needs medical care. Anyone with a higher baseline risk should avoid MT-2.
- No human safety data exists for these groups. MT-2 should not be used during pregnancy or while breastfeeding.
- There is little drug-interaction data. People on blood pressure, ED, or psychiatric medications should review options with a clinician first.
Factors noted in the research literature; not patient-specific medical advice.
Regulatory Status
Regulatory status
RUO
Comparisons
Comparisons
| Compound | Mechanism | Route | Status |
|---|---|---|---|
| Melanotan IIthis | A synthetic non-selective melanocortin receptor agonist (including MC1R and MC4R) studied for stimulation of melanogenesis (skin pigmentation) and central melanocortin-mediated activity. | subcutaneous | Investigational / RUO |
| PT-141 | A cyclic heptapeptide melanocortin receptor agonist (MC3R/MC4R), an active metabolite of melanotan II, acting on central melanocortin pathways studied for modulation of sexual-response signaling. | subcutaneous | Investigational / RUO |
| Kisspeptin | A neuroendocrine peptide that activates KISS1R (GPR54) on GnRH neurons to stimulate gonadotropin-releasing hormone secretion, a key upstream regulator of the reproductive axis. | subcutaneous | Investigational / RUO |
| MGF | A splice variant of IGF-1 (IGF-1Ec) produced in response to mechanical stress; its unique C-terminal E-peptide is studied for activation of muscle satellite cells and tissue repair. | subcutaneous | Investigational / RUO |
| MOTS-C | A 16-amino-acid mitochondrial-derived peptide encoded in the 12S rRNA region of mtDNA that activates AMPK and influences nuclear stress-response gene expression, studied for metabolic homeostasis. | subcutaneous | Investigational / RUO |
| NAD+ | An essential coenzyme central to cellular energy metabolism (redox reactions) and mitochondrial function, and a substrate for sirtuins and PARPs in DNA-repair and signaling pathways. | subcutaneous | Investigational / RUO |
| Oxytocin | A nonapeptide hormone acting on oxytocin receptors; studied for roles in uterine contraction, lactation, and central modulation of social and affiliative behavior. | subcutaneous | Investigational / RUO |
Attributes shown for research comparison only; not a statement of efficacy or therapeutic equivalence.
FAQ
Frequently asked questions
Many research frameworks start between 100 and 250 mcg daily for the first 3 days. This is used to check how well nausea and flushing are tolerated. Common loading then steps up to 500 mcg daily.
The plasma half-life is about 1-2 hours, meaning MT-2 clears the bloodstream that quickly. The effects (tanning, appetite, sexual signaling) can last 24-48+ hours because they depend on slower biological changes. Online claims of a '33-hour half-life' confuse those two things.
Most users see some pigment change in 1-2 weeks during loading. Stronger tanning often develops over 4-8 weeks. Lighter skin types usually see changes faster than darker skin types.
A common setup is a 10 mg vial mixed with 2 mL of bacteriostatic water. That gives 5 mg/mL. At that concentration, a 500 mcg dose equals 0.10 mL or 10 units on a U-100 insulin syringe. For other vial or water volumes, use the PepPal calculator .
No. As of June 2026, MT-2 is not approved by the FDA, EMA, MHRA, or TGA for any use. It is sold only as a research compound and is illegal to sell for human use in the US, UK, and Australia.
Nausea and flushing are the most common, especially in the first 1-2 weeks. Appetite drop, fatigue, and yawning are also frequent. Mole darkening and new moles can occur and need to be monitored.
Case reports have documented mole darkening, new moles, and rare melanoma diagnoses after MT-2 use. A direct cause has not been proven in a large trial, but most dermatologists recommend a baseline skin exam, regular mole photography, and stopping use if any mole changes shape, color, or size.
MT-2 is non-selective and produces tanning, sexual, and appetite effects. PT-141 (bremelanotide) is more selective for MC3R/MC4R and is FDA-approved for low sexual desire in women under the brand name Vyleesi. PT-141 has minimal tanning effect.
Afamelanotide (sometimes called Melanotan I) is MC1R-preferring and is FDA-approved as Scenesse for a rare skin condition called erythropoietic protoporphyria. It is delivered as a subcutaneous implant. MT-2 hits more receptors and has a broader observed effect profile.
Subcutaneous injection is the most studied route and has predictable dose delivery. Intranasal spray has been tested in limited research and varies more from dose to dose because absorption through the nasal lining is less consistent. Most published dosing data is from injection.
10 mg lyophilized vials are the standard format for research-grade Melanotan 2.
2 mL is the most common choice because the unit math at 500 mcg comes out to a clean 10 units. 1 mL, 3 mL, and 5 mL are also used. The reconstitution table above shows the syringe units for each option.
Early clinical studies reached around 0.025-0.03 mg/kg, which is roughly 1.75 mg at 70 kg (154 lb). Overdose case reports describe severe toxicity (including rhabdomyolysis) at much higher self-administered doses.
Store reconstituted vials at 35.6-46.4F (2-8C) and protect from light. For longer storage, split the vial into single-use aliquots and freeze them. Avoid repeat freeze-thaw cycles.
MT-2's observed effect profile and broad receptor activity made it difficult to develop for any one approved use. Researchers pivoted to more selective compounds: afamelanotide for tanning indications and PT-141 for sexual function. Both reached FDA approval. MT-2 never did.
No. This page is an educational research reference. Personal medical decisions should involve a licensed clinician. Peptide Dosing Protocols does not sell Melanotan 2 and is not responsible for off-label use.
Research-use notice
Research Use Only. This educational content and calculation support is intended for private research documentation. It does not provide medical advice, human-use directions, or claims of safety or effectiveness.