PT-141 is the peptide people look at when the problem is wanting sex, not the mechanics of it. Viagra and Cialis work on blood flow. PT-141 works in the brain, and it is one of the few research peptides that went all the way through trials to become an approved drug, in the United States.
Here is what PT-141 is, where it came from, what the trial data shows, the dose that was approved, and the side effects, which are more common than most product pages admit.
How PT-141 works
PT-141 is the research name for bremelanotide. It is a small synthetic peptide that switches on melanocortin receptors, the same family of receptors that control skin pigment, appetite and, it turns out, sexual desire. The receptors that matter most at normal doses are MC1R and MC4R.
It is thought to act through MC4R in the brain. The official label is careful here: it says the exact mechanism behind the effect on desire is not known.
Where it came from: melanotan II
PT-141 started as a side effect. Researchers at the University of Arizona were developing melanotan peptides as sunless tanning agents, and men in early melanotan II studies reported erections. Palatin Technologies took that finding and developed bremelanotide, a closely related peptide, as a sexual dysfunction drug.
The first version was a nasal spray, tested in men with erectile dysfunction and in women. In 2007 the FDA halted those trials because of blood pressure increases. Palatin dropped the nasal spray, moved to an injection under the skin, and focused on women.
That is why searches for “PT-141 nasal spray” turn up so little. The nasal form is the one that was abandoned.
Vyleesi: the approved version
In June 2019 the FDA approved bremelanotide as Vyleesi, for premenopausal women with acquired, generalized hypoactive sexual desire disorder: low desire that developed after a period of normal desire, is not limited to one partner or situation, and causes distress.
Approval rested on two 24-week trials in about 1,250 women. Women on bremelanotide reported more desire and less distress about low desire than women on placebo. The improvement was real but modest, and independent reviewers said as much.
It is not approved in Canada. There is no bremelanotide product in Health Canada’s Drug Product Database, so no pharmacy here can fill a prescription for it. It is not approved for men anywhere.
PT-141 vs Viagra and Cialis
| PT-141 | Viagra / Cialis | |
|---|---|---|
| Works on | Desire, in the brain | Blood flow to the penis |
| Drug type | Melanocortin receptor agonist | PDE5 inhibitor |
| Treats | Low desire | Erection problems; still needs arousal to work |
| How it is taken | Injection under the skin | Tablet |
| Approved for | Low desire in premenopausal women (US only) | Erectile dysfunction in men |
If the problem is erections, the tablets are the better-studied option. Our post on daily Cialis in Canada covers that route.
How much PT-141 to take
The only dose with full trial data behind it is the Vyleesi dose:
- 1.75 mg, injected under the skin of the stomach or thigh
- At least 45 minutes before sex
- No more than one dose in 24 hours
- No more than 8 doses a month
- Stop after 8 weeks if it has not helped
Its half-life is short, about 2.7 hours, so it is taken when needed, not every day.
Our 10 mg vial, mixed
Our PT-141 is a 10 mg vial of powder. Mixed with 2 mL of bacteriostatic water:
| Water added | Strength | 1.75 mg is | On a U-100 insulin syringe |
|---|---|---|---|
| 2 mL | 5 mg per mL | 0.35 mL | 35 units |
That gives five 1.75 mg doses from one vial, with a little left over.
The catch: nausea and blood pressure
These are from the placebo-controlled Vyleesi trials:
| Side effect | Bremelanotide | Placebo |
|---|---|---|
| Nausea | 40% | 1.3% |
| Flushing | 20% | 0.3% |
| Injection site reactions | 13% | 8% |
| Headache | 11% | 2% |
| Vomiting | 5% | 0.2% |
Nausea is the big one. It was worst after the first dose, about 21% of people, and dropped to around 3% with later doses. Even so, 18% of women on bremelanotide stopped because of side effects, against 2% on placebo.
Blood pressure. Each dose raised blood pressure by up to 6 mmHg systolic and 3 mmHg diastolic, peaking 2 to 4 hours after the shot and back to normal within about 12 hours. Heart rate dropped by up to 5 beats a minute. The label rules it out for anyone with uncontrolled high blood pressure or heart disease.
Darker skin patches. Like melanotan, it can darken skin. In the trials, with up to 8 doses a month, it happened to 1% of women. In a study where it was taken every day for 8 days, 38% developed darker patches. Daily use is a bad idea for that reason alone.
Naltrexone. It can sharply cut how much oral naltrexone gets absorbed, so do not combine the two.
Where PT-141 fits
PT-141 has a narrow job. It is for low desire, it is taken as needed, and it has one well-tested dose. The trade-off is nausea, which hits a large share of people the first time. If that is a concern, try the first dose on a day you have nothing planned.
We carry PT-141 10 mg for $45, shipped to Canada or the US. The rest of the range is in our peptides and sexual health sections.
Quick answers
Is PT-141 the same as bremelanotide?
Yes. PT-141 is the research name. Vyleesi is the brand name of the approved injection.
Is PT-141 approved in Canada?
No. It is approved in the US only, and only for premenopausal women with low sexual desire.
How long before sex do you take PT-141?
At least 45 minutes, according to the Vyleesi label.
Does PT-141 work for men?
It was first tested in men with erectile dysfunction, as a nasal spray, but those trials were stopped over blood pressure concerns. There is no approved use in men.
Does PT-141 tan you like melanotan?
It is not a tanning peptide, but it can cause darker skin patches, especially with frequent use. For tanning, people use Melanotan 2.
What is the most common side effect?
Nausea, in 40% of people in the trials, mostly after the first dose.
This article is for information only and is not medical advice. Bremelanotide is not approved by Health Canada. Anyone with high blood pressure or heart disease should not use it. Prices current October 2026.
