Peptides/Sex and libido
Bremelanotide
Also sold as Vyleesi, PT-141
An approved medicine for low sexual desire in premenopausal women, and the only one that works on the brain rather than blood flow.
At a glance
What people use it for
- Low sexual desire that causes distress, in premenopausal women
- Taken before sex rather than daily
- Used off-label by men for erectile difficulty
How it is taken
An injection under the skin of the thigh or stomach, using an auto-injector, around 45 minutes before sex.
Evidence
Mixed human studies
Best known for
- FDA approved in 2019, for a problem with almost no good options
- Works on desire itself rather than on blood flow
- Taken before sex rather than every day
- Two randomised placebo-controlled trials behind the licence
Bremelanotide is genuinely unusual on this site: a peptide, approved by the US Food and Drug Administration, for a problem that had almost no good options. It was licensed in 2019 as Vyleesi for hypoactive sexual desire disorder in premenopausal women.
Most treatments in this area work on blood flow. This one works in the brain, on melanocortin receptors involved in sexual motivation. It addresses desire rather than mechanics.
Why people are talking about it
Because it targets the right thing. The tablets everyone has heard of act on the plumbing, which is useful when the plumbing is the problem and useless when the problem is wanting to in the first place. Bremelanotide acts upstream of that.
It is also taken as needed rather than daily, which for an intermittent problem is a considerably better fit than a pill every morning.
What people take it for
Low sexual desire that is genuinely distressing and not explained by relationship problems, another medical condition or a medication. It is taken roughly 45 minutes beforehand.
It is also used off-label by men for erectile difficulty, particularly where the usual tablets have not worked.
Desire rather than blood flow
The claim is wanting sex more, rather than being more able to have it. The mechanism is agonism at melanocortin receptors, principally MC4R, in brain regions involved in sexual motivation.
In practice that describes acting on the part of the system that generates interest. This was measured in two randomised placebo-controlled trials, RECONNECT, in premenopausal women with a diagnosed desire disorder.
Off-label use in men
The claim is an erection where sildenafil and its relatives have not worked, on the same central mechanism, which is why it can in principle help where a blood flow drug cannot.
The evidence is thinner here. Early studies in men were run before the drug was repositioned, and the licence covers premenopausal women.
What the evidence shows
The registration trials met their endpoints, which is why it was approved. Women on bremelanotide reported greater improvement in desire and less distress than those on placebo.
The honest caveat is size. The average improvement was modest, and the placebo response in this area is large. Approval means it works better than nothing to a statistically reliable degree, and reviewers have been openly divided on whether the benefit justifies the nausea.
Nausea is the main reason people stop, and it affected a large minority in the trials. Flushing, headache and injection site reactions are frequent.
How it is taken
The licensed product is a single-use auto-injector used into the thigh or abdomen roughly 45 minutes before sex, with a limit on how often it may be used in a day and in a month.
That limit exists partly for blood pressure and partly for the pigmentation effects, and it is part of the label rather than a suggestion.
How it compares
Against flibanserin
Flibanserin is the other approved option for the same condition and is taken daily rather than before sex, with its own tolerability profile including interactions with alcohol. Neither produces a large average effect, and the choice is usually about how each one fits a life.
Against erectile dysfunction tablets
Those work on blood flow in the genitals. Bremelanotide works on motivation in the brain. They address different halves of the problem, and one does not substitute for the other.
Against Melanotan II
Melanotan II is the compound bremelanotide was developed from, with the tanning activity engineered out and the safety work done. This is what that compound looks like when it is developed properly.
Common questions
Does it work for men?
It is not licensed for men. Early research included men, and current use in that group is off-label.
Is PT-141 the same thing?
PT-141 is the research name for the same molecule. A vial sold under that name is not the licensed product.
How long does it last?
The effect is intended for a single occasion, with dosing around 45 minutes beforehand. It is not a daily medicine.
Why an injection rather than a tablet?
A peptide this size would not survive digestion, which is why the auto-injector exists.
Last reviewed .