Peptides
PT-141 (Bremelanotide): Uses, Dosing, and Evidence
PT-141 (bremelanotide) is a melanocortin peptide for sexual desire and arousal. How it works, FDA-approved Vyleesi, common dosing, side effects, and the skin-darkening risk.
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PT-141 is unusual among the peptides people inject: it has a clear, FDA-approved use, a well-defined mechanism, and a side-effect profile that's genuinely distinctive. It also gets marketed well beyond its evidence, like most of the category. Here's what it actually is and how it's used.
PT-141 (bremelanotide) is a melanocortin receptor agonist that acts on the brain to influence sexual desire and arousal. It's approved as Vyleesi for low sexual desire in premenopausal women, and used off-label by men for libido and erectile dysfunction. What sets it apart from Viagra and similar drugs is the pathway: PT-141 works centrally on desire, not on blood flow.
Quick Reference
| Drug class | Melanocortin receptor agonist (primarily MC4R) |
| Approved form | Vyleesi (bremelanotide), 1.75 mg SubQ auto-injector |
| Approved use | Acquired, generalized HSDD in premenopausal women |
| Off-label use | Male libido and erectile dysfunction |
| Route | Subcutaneous injection (originally trialed as a nasal spray) |
| Onset | Taken ≥45 minutes before activity; half-life ~2.7 hours |
| Evidence level | Strong for HSDD in women; thinner for men |
| Signature side effects | Nausea (dose-limiter), skin hyperpigmentation |
How PT-141 Works
Most sexual-function drugs people know — sildenafil (Viagra), tadalafil (Cialis) — are PDE5 inhibitors. They're vascular: they improve blood flow to the genitals so that an erection can occur in response to arousal. They do nothing for desire itself.
PT-141 works on a different system entirely. It activates melanocortin receptors in the central nervous system — chiefly MC4R in the hypothalamus — which are part of the brain's circuitry for sexual desire and arousal. In other words, it acts upstream, on the wanting rather than the plumbing. That's the whole reason it exists as a separate class: it targets low desire, which the PDE5 drugs can't touch.
The trade-off is that hitting the melanocortin system also reaches the receptors that control pigment and cardiovascular tone, which is where its characteristic side effects come from (more below).
The Evidence
In women (strong): Bremelanotide was approved as Vyleesi in 2019 on the strength of the RECONNECT Phase 3 program — two large, randomized, placebo-controlled trials in premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). It produced statistically significant improvements in desire and reductions in distress versus placebo. The effect sizes were modest but real, and the approval is specific: acquired, generalized HSDD in premenopausal women.
In men (thinner): PT-141 was originally developed for sexual dysfunction broadly, including men, and early-phase studies showed effects on erectile response. But the men's development path didn't reach the same FDA-approved finish line, and the nasal-spray formulation was halted partly over blood-pressure increases. So male use today is off-label, on a less robust evidence base than the women's HSDD indication. Most of what circulates about male dosing is community experience, not trial data — worth knowing when you read confident claims online.
Forms and How It's Used
Vyleesi (approved): A single-use 1.75 mg subcutaneous auto-injector, used in the abdomen or thigh at least 45 minutes before anticipated sexual activity. The label caps it at one dose per 24 hours and no more than 8 doses per month — it's an as-needed product, not a daily one. The monthly cap matters for the hyperpigmentation risk.
Research vials (off-label): PT-141 is also sold as a lyophilized powder in vials for reconstitution and subcutaneous injection. This is the form most off-label users encounter, and it carries the usual gray-market caveats: no guarantee of purity or dose accuracy, and "for research use only" labeling. If you are reconstituting a vial, getting the mixing and dose math right is the difference between a known dose and a guess — see the peptide reconstitution guide, and the bacteriostatic water guide for what to mix it with.
Nasal (discontinued): The original intranasal formulation was dropped during development due to blood-pressure effects. Subcutaneous is the route that made it through.
Dosing
For the approved product, the dose is fixed: 1.75 mg, no more than once per 24 hours, no more than 8 times per month.
For off-label research-vial use, dosing is not standardized, and we won't invent a protocol — reported ranges are generally lower than the Vyleesi dose and timed roughly 45 minutes to a few hours before activity, but this is community practice, not a validated schedule. Two honest points:
- Nausea is the dose-limiter. People who titrate up too fast mostly find the ceiling by feeling sick, not by feeling more effect.
- Frequency drives the pigment risk. This is an as-needed peptide for a reason. Frequent dosing is where skin-darkening shows up.
If you're considering it, the dose conversation belongs with a provider who can weigh your blood pressure and cardiovascular history — not a vendor's suggested-use card. For the injection mechanics, PT-141 is a standard subcutaneous shot; see the subcutaneous injection technique guide and peptide injection sites, and the needle size chart for the right syringe.
Side Effects
PT-141 has a few effects that are common and a couple that are specific to its mechanism:
- Nausea — by far the most common, reported by roughly 40% of participants in trials, and dose-related. It's usually the limiting factor. Some people find it eases with food or a lower dose.
- Flushing and headache — common, generally transient.
- Injection-site reactions — mild redness or irritation.
- Blood pressure and heart rate — PT-141 causes a transient increase in blood pressure and a small decrease in heart rate for several hours after dosing. This is the reason it's not recommended for people with uncontrolled hypertension or known cardiovascular disease, and the reason the nasal form was abandoned.
- Skin hyperpigmentation — the signature melanocortin effect. Because PT-141 stimulates the same receptor family that controls pigment, it can cause focal darkening of the skin — patches on the face, darkening of the gums, and other areas — particularly with frequent or repeated dosing. It's a real, documented effect and a key argument against daily use.
Who Should Avoid It
Beyond the gray-market sourcing concerns that apply to any research peptide, PT-141's cardiovascular profile makes it a poor fit for anyone with uncontrolled high blood pressure or cardiovascular disease. The blood-pressure bump is modest and temporary in healthy people, but it's not trivial in the wrong person. As with anything in this category, the right move is a conversation with a licensed provider rather than a purchase based on a landing page.
Tracking PT-141
Because PT-141 is as-needed and has a monthly cap (and a frequency-linked pigment risk), it's worth actually logging — dose, date, timing relative to activity, side effects like nausea severity, and any skin changes. That record makes the every-detail-matters parts easy: staying under the monthly limit, spotting whether nausea is improving or pigment is creeping in, and having real data if you discuss it with a provider.
Done Dose tracks injectable peptides like this in one place — dose logging, injection-site rotation, and a history you can actually review instead of reconstructing from memory. If you're running multiple peptides, the best peptide tracker app comparison covers how the options stack up. Set it up in under a minute.
