Skip to content
PeptideAI
Animal data onlyinflammationimmuneskintanning

Alpha-MSH

The natural thirteen-amino-acid melanocortin that shuts down NF-kB-driven inflammation across nearly every tissue, and the parent molecule of both KPV and the melanotans.

Also known as α-MSH, alpha-melanocyte-stimulating hormone, melanotropin, alpha-melanotropin

Animal data only — Rodent or other animal studies. Dose translation to humans is genuinely uncertain.

The anti-inflammatory biology of alpha-MSH is genuinely well established at the mechanistic and animal level and has driven approved drugs derived from it. Native alpha-MSH itself has almost no human therapeutic trial data, mainly because its half-life makes it impractical as a drug.

How it works

Alpha-MSH is Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2, cleaved from pro-opiomelanocortin. It is a non-selective agonist across the melanocortin receptor family: MC1R on melanocytes and immune cells drives both pigmentation and anti-inflammatory signalling, MC3R and MC4R mediate central anti-inflammatory, appetite and sexual effects, and MC5R affects exocrine glands. The dominant anti-inflammatory mechanism is cAMP-driven inhibition of NF-kB nuclear translocation, which cuts TNF-alpha, IL-1, IL-6, nitric oxide synthase and adhesion molecule expression at source. The C-terminal KPV tripeptide retains most of the anti-inflammatory activity without the pigmentary and central effects, which is precisely why KPV exists as a separate compound. Alpha-MSH is also a mediator of interest in CIRS and mould-illness frameworks, where low alpha-MSH is treated as a marker - that association is real in some patient series but the treatment claims built on top of it are not established.

Targets: MC1R, MC3R, MC4R, MC5R, NF-kB pathway

Dosing

ProtocolDoseFrequencyRoute
Research anti-inflammatory protocolEvening, since the melanocortin side effects are easier to sleep through.100 mcg – 500 mcgonce dailysubcutaneous
  • · No human dose is established for native alpha-MSH. This range is research-supplier convention. Because the peptide is degraded within minutes, most people chasing anti-inflammatory effects are better served by KPV, and those chasing tanning by a stabilised MC1R analogue.

Titration

Start at the low end. Non-selective melanocortin agonism means nausea, flushing, spontaneous erections and darkening of moles are all on the table at higher doses.

Cycling

No established cycle. Short blocks of two to four weeks are the norm among users, largely by default.

Work out your exact syringe units →

Pharmacology

Half-life
Extremely short - degraded within minutes in plasma, which is the main reason stabilised analogues like afamelanotide and Melanotan II were developed.
Onset
Pigmentation changes over one to three weeks with repeated dosing; anti-inflammatory effects in animal models are acute.
Routes
subcutaneous, intranasal
Molecule
Endogenous tridecapeptide (POMC-derived melanocortin)
Sequence length
13 amino acids
Molecular weight
1664.9 Da

Handling

Diluent
Bacteriostatic water
Typical mix
2 or 3 mL
Vial sizes
1, 5, 10 mg
Lyophilised
Fridge or freezer; this peptide is not especially stable.
Reconstituted
Refrigerated, use within about 14-21 days.
Light sensitive
Yes — keep it out of the light

Oral — not a viable route

Cleared from plasma within minutes even by injection; oral dosing does not deliver an intact peptide at all. This instability is exactly why the stabilised analogues exist.

Intranasal — usable, with a caveat

Intranasal alpha-MSH has been studied in humans, mostly for central effects on appetite and inflammation rather than for tanning, and the route exists because the peptide is destroyed within minutes in plasma by any route. That same instability is the catch: nasal dosing does not fix a molecule that clears in minutes, it only changes where the clock starts. The stabilised analogues - afamelanotide, Melanotan II - were developed precisely because the native hormone is impractical.

Mixing

A 5 mg vial in 2 mL gives 2.5 mg/mL, so 250 mcg is 10 units on a U-100 syringe.

Side effects

  • commonFacial flushing— Usually within 30 minutes of injection.
  • commonNausea— Dose-dependent, MC4R-mediated.
  • commonSkin darkening and darkening of existing moles— MC1R-mediated; new or changing moles need dermatological assessment, not reassurance.
  • commonSpontaneous erections— Same MC4R mechanism that made PT-141 a drug.
  • commonAppetite suppression— Often unwanted at the doses required for other effects.
  • uncommonBlood pressure changes— Melanocortins can transiently raise blood pressure.

Do not use if

  • History of melanoma or dysplastic naevus syndrome - stimulating melanocytes in that setting is a genuinely bad idea.
  • Uncontrolled hypertension.
  • Pregnancy - no data and clear hormonal activity.

Combining it

  • redundantkpv — KPV is the anti-inflammatory C-terminal fragment of this molecule, with none of the pigmentation or MC4R effects.
  • redundantmelanotan-ii — Melanotan II is a stabilised, far longer-acting version of the same pharmacology.
  • cautionpt-141 — Additive MC4R activation - nausea and blood pressure effects stack.

What to monitor

  • · Annual full-skin dermatology check if used for more than short periods, and immediately for any changing mole.
  • · Blood pressure during the first weeks of use.

Legal status

Not approved as a drug in native form. Derived analogues (afamelanotide, bremelanotide) are approved; alpha-MSH itself is sold as a research chemical.

References

  • Catania and colleagues, targeting melanocortin receptors to control inflammation (Pharmacological Reviews) (review)
  • Alpha-MSH inhibition of NF-kB activation in inflammatory models (preclinical)

Mechanism in depth

The anti-inflammatory mechanism is the part worth understanding in detail because it is unusually clean. Manna and Aggarwal showed in 1998 that alpha-MSH blocks NF-kB activation induced by TNF, ceramide, okadaic acid and hydrogen peroxide - four completely unrelated stimuli - which places the block downstream of all of them, at the level of IkB-alpha degradation and NF-kB nuclear translocation itself. Because NF-kB is the master transcriptional switch for TNF-alpha, IL-1, IL-6, iNOS, COX-2 and the adhesion molecules, blocking translocation shuts off the entire programme at source rather than neutralising one cytokine downstream. That is a fundamentally different kind of anti-inflammatory action from anakinra, which blocks exactly one receptor. The route to it is cAMP: melanocortin receptors are Gs-coupled, cAMP rises, protein kinase A activity increases, and IkB-alpha degradation is inhibited. The complication is that alpha-MSH is non-selective across MC1R through MC5R, so the same cAMP rise that produces the anti-inflammatory effect in immune cells produces melanogenesis at MC1R in melanocytes, appetite suppression and erectile effects at MC4R in the hypothalamus, and exocrine gland effects at MC5R. You cannot get one without the others with the native peptide. The pharmacological solution the field found is exactly the C-terminal fragment: KPV retains NF-kB inhibition without meaningful melanocortin receptor agonism, and Haddad's 2001 work on the related Lys-D-Pro-Val showed the tripeptide also antagonises IL-1 beta signalling directly. Understanding that is the whole practical argument for taking KPV instead of alpha-MSH if inflammation is what you want.

What usually goes wrong

The single most consequential problem is diagnostic, not toxicological: MC1R agonism darkens existing naevi, which degrades your ability and your dermatologist's ability to spot the change that matters. Anyone with a history of melanoma or dysplastic naevus syndrome should not be taking this, and everyone else should have baseline photographs. The routine problems arrive within the first hour of the first dose - facial flushing, nausea, and spontaneous erections in men, all MC4R-mediated and all dose-dependent, which is why the ladder exists. Appetite suppression is common and frequently unwanted. Blood pressure can rise transiently. The structural failure mode is pharmacokinetic: at a plasma half-life measured in minutes, most people chasing sustained anti-inflammatory effect are dosing a molecule that is gone before it has done much, then escalating into the MC4R side effects in search of an effect the molecule cannot sustain. That is the specific error KPV and the stabilised analogues exist to solve.

Titration ladder

  1. 100 mcgDays 1-3 — Convention rather than evidence - there is no human dose-ranging study for native alpha-MSH. The reason to start here is that nausea, flushing and blood pressure effects are MC4R-mediated and dose-dependent, and they arrive within 30 minutes of the first dose.
  2. 200 mcgDays 4-7 — Hold here for a full three days before going further. If flushing or nausea appeared at 100 mcg they will be worse here, and that is the signal to stop rather than to push through.
  3. 500 mcgWeek 2 onward — The top of the range research suppliers describe. There is no evidence that going above this does anything except increase MC4R side effects, and given a plasma half-life measured in minutes, dose escalation is a poor substitute for a stabilised analogue.

Bloodwork worth running

MarkerWhenWhy it matters
Blood pressure (not bloodwork, but the measurement that matters most in the first fortnight)Before the first dose and 30-60 minutes after, then daily for the first week.Melanocortins transiently raise blood pressure through central MC4R signalling. This is a documented class effect, not theoretical.Act if: A sustained rise above 140/90 in someone previously normotensive, or any symptomatic rise, means stop.
hs-CRPBaseline and at four weeks.If you are taking this for inflammation rather than pigmentation, this is the endpoint. NF-kB blockade should lower IL-6 and therefore CRP.Act if: No fall by four weeks in someone with an elevated baseline means the compound is not reaching the target at your dose - and given the half-life, switching to KPV is the more sensible next step than raising the dose.
Full-body skin examination by a dermatologist, with photography of existing naeviBefore starting, and annually thereafter. Immediately for any lesion that changes shape, border or texture rather than just colour.MC1R agonism darkens existing moles as well as producing a tan. That makes the single most important melanoma screening cue - a mole that has changed - unreliable for as long as you are dosing. Baseline photographs are the only way to preserve the ability to interpret a change later.Act if: Any change in a naevus other than uniform darkening warrants dermatological assessment, not reassurance that it is just the peptide.
Basic metabolic panel and weightBaseline and at four weeks.MC4R-driven appetite suppression is real and dose-dependent, and unintended weight loss with reduced intake is worth catching.Act if: Unintended loss of more than about 5 percent of body weight means the dose is too high for your purpose.

Pharmacokinetics

Crosses blood-brain barrier
partial
Metabolism
Rapid proteolysis. The N-terminal acetyl group blocks aminopeptidase attack and the C-terminal amide blocks carboxypeptidase attack, which is why alpha-MSH survives minutes rather than seconds - but endopeptidase cleavage, particularly around the Met4 and the His-Phe-Arg-Trp core, still destroys it fast. The C-terminal KPV tripeptide is a degradation product that retains most of the anti-inflammatory activity, which is not a coincidence and is why KPV exists as a compound.
Elimination
Peptide catabolism.

Receptor targets

  • MC1R (melanocytes, monocytes, macrophages, neutrophils) — Sub-nanomolar to low-nanomolar for alpha-MSH in most published binding studies; specific values vary by preparation and were not re-verified in this session

    Gs-coupled cAMP rise. On melanocytes: eumelanin synthesis, i.e. tanning and darkening of existing naevi. On immune cells: the principal anti-inflammatory receptor, driving NF-kB blockade.

  • MC3R (CNS, macrophages) — Nanomolar range for alpha-MSH

    Central anti-inflammatory signalling and energy-homeostasis effects. MC3R is the receptor most associated with the systemic anti-inflammatory action of melanocortins acting through the brain.

  • MC4R (hypothalamus) — Nanomolar range

    Appetite suppression, nausea, transient blood pressure elevation and spontaneous erections. This is the receptor that made bremelanotide a drug and the reason the side-effect profile is what it is.

  • MC5R (exocrine glands) — Lowest affinity of the family for alpha-MSH

    Sebaceous and other exocrine gland regulation. Clinically minor at these doses.

  • NF-kB / IkB-alpha pathway (downstream, not a binding site) — Not applicable

    Inhibition of IkB-alpha degradation and NF-kB nuclear translocation, blocking TNF-alpha, IL-1, IL-6, iNOS, COX-2 and adhesion molecule transcription. Demonstrated against four mechanistically unrelated activating stimuli.

What to expect, and when

Minutes 0-30: flushing, and in some people nausea. This is MC4R and it is the fastest, most reliable thing the compound does. Minutes 30-90: spontaneous erections in men; appetite suppression begins. Hours 1-4: the peptide is essentially gone from plasma. Days 3-7: appetite suppression becomes a pattern rather than an event if dosing daily. Weeks 1-3: pigmentation changes become visible with repeated dosing - existing moles darken first, general tan follows. Weeks 2-4: any anti-inflammatory effect on CRP would be measurable here, though the evidence that it happens in humans at these doses is not strong. Months: nobody has studied this compound over months in people.

Stacking and comparisons

Do not stack alpha-MSH with PT-141 or Melanotan II. All three are melanocortin agonists, MC4R activation is additive, and nausea plus blood pressure effects stack in a way that is genuinely unpleasant rather than merely inconvenient. KPV is not a stack partner either - it is the fragment of this molecule, so running both is paying twice for overlapping activity with the added pigmentation and MC4R baggage. The rational pairing is with something acting on a different inflammatory node: lactoferrin on the luminal and TLR4 side in gut protocols, or a genuine IL-1 blocker if the disease warrants it. In the CIRS and mould-illness framework alpha-MSH is treated as a marker to be corrected, and that framework's treatment claims go well beyond what the melanocortin literature supports - low alpha-MSH in those patient series is a real observation, but replacing it has not been shown to do anything.

Alpha-MSH is the parent molecule of an entire drug class and is itself the least practical member of it. If you want the anti-inflammatory action, KPV is the C-terminal fragment that retains it without pigmentation or MC4R effects, and it is cheaper. If you want pigmentation, afamelanotide is an approved implant and Melanotan II is the stabilised analogue people actually use. If you want the sexual-function effect, bremelanotide is an approved drug. In every direction there is a better-engineered option, which is exactly why native alpha-MSH has essentially no human trial data - not because it does not work, but because it works for minutes. Within this class, its NF-kB mechanism makes it the most broadly anti-inflammatory compound here in principle, far broader than anakinra's single-receptor block, and the least deliverable in practice.

Rough cost

$40–$120/month. A 5 mg vial runs roughly a month at 100-500 mcg daily. Typical research-supplier pricing rather than a verified survey. KPV is generally cheaper per anti-inflammatory dose and Melanotan II cheaper per unit of pigmentation, which tells you something about where native alpha-MSH sits commercially.

Genuinely uncertain

  • No human pharmacokinetic profile exists for native alpha-MSH by any route. Tmax, bioavailability, volume of distribution and clearance are all genuinely unpublished.
  • The receptor affinity figures given are described in general terms because specific published Kd values were not re-verified against primary sources in this session. Treat the affinity fields as directional, not quotable.
  • Blood-brain barrier penetration is marked partial on the basis that peripheral melanocortin administration produces central effects such as appetite suppression, but the extent of direct transport versus indirect signalling is not resolved.
  • The intranasal route rests on assumed nose-to-brain transport that has not been quantified for this peptide.
  • The 100-500 mcg dose range is supplier convention. No human dose-ranging study for native alpha-MSH was found.
  • Whether alpha-MSH lowers CRP or any other inflammatory marker in humans at achievable doses has not been demonstrated. The NF-kB mechanism is solid; the human clinical translation of it, for the native peptide, is not.
  • The CIRS and mould-illness framework's use of low serum alpha-MSH as a diagnostic marker and treatment target sits outside the mainstream melanocortin literature and could not be assessed against controlled data.
  • The trials array is empty because no human therapeutic trial of native alpha-MSH was identified - the approved melanocortin trials all used stabilised analogues, not this molecule.

Papers