Is either icariin or Melanotan II FDA-approved?

No. Icariin is sold as a supplement; not a proven treatment for erectile dysfunction or low testosterone. Melanotan II is not approved by the FDA or any major regulator; sold as gray-market injectable powder.

Which has stronger human evidence, icariin or Melanotan II?

Melanotan II. It has human clinical data (key source: Habbema, Int J Dermatol 2017), while icariin has only preclinical or minimal evidence (key source: PDE5 inhibition mechanism, J Nat Prod 2008).

What are the main safety concerns with icariin and Melanotan II?

For icariin, watch for rare reports of liver injury; actual icariin content varies widely between products. For Melanotan II, watch for new and darkening moles; also nausea, flushing, blood pressure effects and priapism.

Head-to-head

Icariin vs Melanotan II

Two libido-adjacent products with opposite risk profiles — a weak herbal PDE5 inhibitor with essentially no human trial data, against an unapproved gray-market injectable with a documented harm record.

By Julian RothResearch & dataUpdated October 2026

Short answer

The evidence gap decides this one. Melanotan II has human clinical data behind it, while icariin has only preclinical or minimal evidence, resting mostly on animal or lab work. Someone focused on tanning and libido has trial data to go on with Melanotan II; icariin, marketed for erectile function, libido and testosterone, is still an early-research option.

Icariin

Horny goat weed, Epimedium

Preclinical / minimal

A flavonoid from Epimedium with a real in-vitro PDE5-inhibition mechanism — the same drug class as sildenafil, just far weaker and poorly bioavailable — and essentially no human clinical-trial data at the doses and purity typically sold.

Full Icariin evidence review

Melanotan II

MT-2

Clinical data

Genuinely tans skin via MC1R, but it's an unapproved gray-market injectable with a documented harm record (priapism, changing moles) — and it is not the approved drug afamelanotide.

Full Melanotan II evidence review

Icariin vs Melanotan II: head to head

FDA status / approved use: Icariin
Sold as a supplement; not a proven treatment for erectile dysfunction or low testosterone
Melanotan II
Not approved by the FDA or any major regulator; sold as gray-market injectable powder
Marketed for: Icariin
Erectile function, libido, testosterone
Melanotan II
Tanning, libido
Outcome areas: Icariin
Sexual health / libido; Testosterone / male hormones
Melanotan II
Skin / hair; Sexual health / libido
Evidence grade: Icariin
Preclinical / minimal
Melanotan II
Clinical data
How it works: Icariin
Weakly inhibits PDE5, the same enzyme sildenafil blocks
Melanotan II
Activates the melanocortin-1 receptor on pigment cells, driving melanin production
Route and dosing: Icariin
Oral capsule of horny goat weed (Epimedium) extract
Melanotan II
Self-injected after reconstituting a powder; no standard dose
Headline human result: Icariin
Not established
Melanotan II
Not established
Strongest evidence: Icariin
PDE5 inhibition mechanism, J Nat Prod 2008. Little or no controlled human outcome data for the marketed useIcariin evidence reviewPubMed 18778098
Melanotan II
Habbema, Int J Dermatol 2017Melanotan II evidence reviewPubMed 28266027
Key safety signal: Icariin
Rare reports of liver injury; actual icariin content varies widely between products
Melanotan II
New and darkening moles; also nausea, flushing, blood pressure effects and priapism
How it is obtained: Icariin
Over the counter as a dietary supplement
Melanotan II
Sold gray-market as a research chemical; no approved or legitimately compounded human product

	Icariin	Melanotan II
FDA status / approved use	Sold as a supplement; not a proven treatment for erectile dysfunction or low testosterone	Not approved by the FDA or any major regulator; sold as gray-market injectable powder
Marketed for	Erectile function, libido, testosterone	Tanning, libido
Outcome areas	Sexual health / libido; Testosterone / male hormones	Skin / hair; Sexual health / libido
Evidence grade	Preclinical / minimal	Clinical data
How it works	Weakly inhibits PDE5, the same enzyme sildenafil blocks	Activates the melanocortin-1 receptor on pigment cells, driving melanin production
Route and dosing	Oral capsule of horny goat weed (Epimedium) extract	Self-injected after reconstituting a powder; no standard dose
Headline human result	Not established	Not established
Strongest evidence	PDE5 inhibition mechanism, J Nat Prod 2008. Little or no controlled human outcome data for the marketed useIcariin evidence reviewPubMed 18778098	Habbema, Int J Dermatol 2017Melanotan II evidence reviewPubMed 28266027
Key safety signal	Rare reports of liver injury; actual icariin content varies widely between products	New and darkening moles; also nausea, flushing, blood pressure effects and priapism
How it is obtained	Over the counter as a dietary supplement	Sold gray-market as a research chemical; no approved or legitimately compounded human product

marks a row where the two differ. “Not established” marks a cell the available evidence does not answer. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.

Clinical data:: Tested in humans — but investigational, discontinued, or proven only on a surrogate marker (not the marketed outcome).
Preclinical / minimal:: Evidence is largely animal, in-vitro, or anecdotal. Little or no controlled human outcome data for the marketed use.

Our verdict

Icariin has a real in-vitro PDE5-inhibition mechanism, the same class as sildenafil, just far weaker and poorly bioavailable, with essentially no human clinical-trial data at typical supplement doses. Melanotan II genuinely tans skin and has real central sexual-arousal effects via MC1R/melanocortin pathways, but it's an unapproved gray-market injectable with documented harms — priapism, changing moles — and it isn't the same as the approved drug afamelanotide.

Icariin fits if

You want the oral, non-injectable option and accept the mechanism is real but weak, with no human trial confirming an actual effect.

Melanotan II fits if

You understand this is an unregulated injectable with a documented harm profile, not a supplement — and that the approved cousin drug is a different, safer product.

Icariin vs Melanotan II: common questions

Is either icariin or Melanotan II FDA-approved?: No. Icariin is sold as a supplement; not a proven treatment for erectile dysfunction or low testosterone. Melanotan II is not approved by the FDA or any major regulator; sold as gray-market injectable powder.
Which has stronger human evidence, icariin or Melanotan II?: Melanotan II. It has human clinical data (key source: Habbema, Int J Dermatol 2017), while icariin has only preclinical or minimal evidence (key source: PDE5 inhibition mechanism, J Nat Prod 2008).
What are the main safety concerns with icariin and Melanotan II?: For icariin, watch for rare reports of liver injury; actual icariin content varies widely between products. For Melanotan II, watch for new and darkening moles; also nausea, flushing, blood pressure effects and priapism.

Key studies behind each

Icariin

Dell'Agli M, Galli GV, Dal Cero E, et al. (2008). Potent inhibition of human phosphodiesterase-5 by icariin derivatives. Journal of Natural Products. PubMed 18778098
Liu QW, Yang ZH, Jiang J, et al. (2021). Icariin modulates eNOS activity via effect on post-translational protein-protein interactions to improve erectile function of spontaneously hypertensive rats. Andrology. PubMed 33507631
Cheng T, Zhang Y, Zhang T, et al. (2015). Comparative Pharmacokinetics Study of Icariin and Icariside II in Rats. Molecules. PubMed 26633326
Xu Y, Xin H, Wu Y, et al. (2017). Effect of icariin in combination with daily sildenafil on penile atrophy and erectile dysfunction in a rat model of bilateral cavernous nerves injury. Andrology. PubMed 28296277

Melanotan II

Habbema L, Halk AB, Neumann M, Bergman W. (2017). Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol. PubMed 28266027
Langan EA, Ramlogan D, Jamieson LA, Rhodes LE. (2009). Change in moles linked to use of unlicensed "sun tan jab". BMJ. PubMed 19174439
Schulze F, Erdmann H, Hardkop LH, Schmidt-Naumann A. (2014). Eruptive naevi and darkening of pre-existing naevi 24 h after a single mono-dose injection of melanotan II. Eur J Dermatol. PubMed 24334249
Devlin J, Pomerleau A, Foote J, et al. (2013). Melanotan II overdose associated with priapism. Clin Toxicol (Phila). PubMed 23537392

The full evidence reviews

Icariin and Horny Goat Weed: What the Evidence Actually Shows
A real PDE5 inhibitor in the test tube with coherent animal data — but weak potency, poor oral absorption, and essentially no rigorous human trials behind the “natural Viagra” label.
Updated August 2026
Melanotan II (MT-2): a real skin-darkening drug with real, unapproved risks
MT-2 genuinely tans skin via the melanocortin-1 receptor — but it’s an unapproved gray-market injectable with a documented harm record, from priapism to changing moles. And it’s not the approved drug afamelanotide.
Updated August 2026

Where to get it

Where to get peptide therapy

Clinician-led telehealth services that prescribe compounded peptides. The specific peptides offered vary by provider — confirm Melanotan II availability before ordering.

Disclosure: Aminoscope is reader-supported. Some links below are affiliate links — if you start care through them we may earn a commission, at no extra cost to you. Partners are listed first; a commission never changes what we write about a provider. How we make money.

Compare all 217 peptide-therapy providers →

Provider reviews we publish: Lean MedsLongevixxMagnolia Regenerative MedicineMondaeNEUVÉ HealthNex Gen Health Rx

Related comparisons

Melanotan II vs PT-141