PT-141 dosage: the 1.75 mg Vyleesi dose, timing, limits and unit math

The label dose of PT-141 (bremelanotide) is a fixed 1.75 mg, injected under the skin as needed before sexual activity, with firm limits on how often. That answer exists because PT-141 is an FDA-approved drug, sold as Vyleesi. There is no ladder of doses to climb and no weight-based math. Your prescriber decides whether it is right for you, and vials sold for research use only are not Vyleesi and are not legal to use on people.

PT-141 dosage: what the FDA label says

Why the limits exist. The label says the efficacy of a second dose within 24 hours has not been established, and doses close together may add to the rise in blood pressure. It says few trial patients used more than 8 doses a month, and more frequent dosing increases the risk of focal hyperpigmentation (patches of darker skin) and the time each month that blood pressure is raised.

When to take it, and how long it lasts

The 45 minutes is a minimum. The label says the duration of effect after each dose is unknown and the best window has not been fully worked out, so patients may choose the timing based on how they experience the effect and side effects such as nausea. Someone who finds the nausea peaks at the wrong moment can raise that with the prescriber.

A half-life is how long the blood level takes to fall by half. It tells you how long the drug is around, and the label is clear that this does not tell you how long the effect on desire lasts.

Missed doses and dose steps

Vyleesi has neither. It is taken only when wanted, so there is no schedule to miss and nothing to make up. It also has no titration, so every dose is the same 1.75 mg. Three checkpoints take the place of dose steps.

1. First dose. Nausea is most likely here: 21% of patients had it after the first dose, falling to about 3% with later doses.
2. Every dose. Blood pressure rises for a few hours, so a second dose within 24 hours is outside the label.
3. Week 8. The label says to stop if there has been no improvement.

How to inject it, and where

Each autoinjector is single use. The label says to inspect the solution first and discard it if it is cloudy, discolored or has visible particles. The patient instructions say to use the abdomen or the front of the thigh, stay 2 inches away from the navel, avoid irritated, bruised or scarred skin, and change sites each time. The upper arm, a usual site for some other injections, is not on the Vyleesi list. Our guide to injection sites covers technique in general.

What the trials actually used

In the two RECONNECT phase 3 trials, women self-injected 1.75 mg about 45 minutes before expected sexual activity. The trial rules allowed one dose in 24 hours and up to 12 doses a month, more than the label now recommends. In practice the median was 10 injections over the 24-week double-blind period and 12 during the open-label extension, and most women used it two or three times a month and no more than once a week.

Doses tested in men

There is no approved dose for men, and the label says Vyleesi is not indicated for them. Before the women’s program, the developer ran small studies in men that measured erections with a laboratory monitor:

These studies were short and did not test regular use, desire, or real-world outcomes. The nasal program was later dropped after FDA raised blood pressure concerns. The label also reports that a 20 mg nasal dose produced peak blood levels about 2.5 times those of the 1.75 mg injection. None of this gives men a validated dose.

Do higher doses work better?

Higher doses add risk without a clear gain. The label reports that blood levels rise less than proportionally between 0.3 and 10 mg and plateau at about 7.5 mg under the skin, roughly 4.3 times the approved dose. It also says nausea, focal hyperpigmentation and larger blood pressure increases are more likely with higher doses. In a study of daily dosing, 38% of women developed focal hyperpigmentation after 8 days.

What compounded products use

A compounded bremelanotide product is not Vyleesi. Its strength, volume, form and dose are set by the prescriber and the pharmacy, and none has an FDA label or a dose reviewed by FDA. Section 503A allows compounding from bulk substances that are components of approved drugs, which bremelanotide has been since 2019, but limits pharmacies to not regularly making copies of a commercially available drug unless a prescriber documents a significant difference for an identified patient. No published trial has tested any compounded bremelanotide product. FDA named “PT-141 (Bremelanotide)” in an August 24, 2026 warning letter to a seller of research-labeled vials, and 21 CFR 312.160 limits such products to laboratory animal and test-tube work.

PT-141 unit math

The Vyleesi autoinjector needs no arithmetic: one press delivers 1.75 mg in 0.3 mL, which is about 5.83 mg/mL. If your pharmacy sent a compounded vial, the math changes. On a U-100 insulin syringe, units measure volume: 100 units is 1 mL, so 1 unit is 0.01 mL. The concentration decides how many units a dose is.

The vial size below is an example for the arithmetic, not a fact about any product.

The table describes arithmetic, not a dose. The mg/mL to units converter below does the same calculation for any concentration, and the reconstitution calculator starts from the vial size and the water added (see how to reconstitute).

Common PT-141 dosing mistakes

• Confusing mg and mcg. 1.75 mg is 1,750 mcg. Reading it as 1.75 mcg is a thousandfold error.
• Treating units as milligrams. A unit is a hundredth of a milliliter and holds whatever the concentration says.
• Copying another person’s units. 35 units is 1.75 mg only if the vial is at 5 mg/mL.
• Stacking doses. The label limit is one dose in 24 hours, whatever the product.
• Using it daily. Daily dosing is what produced skin darkening in 38% of women within 8 days.
• Trusting the vial label. Research-grade vials carry no FDA-verified identity, purity, potency or sterility.

Who should not use PT-141

The label contraindicates Vyleesi in uncontrolled high blood pressure and known cardiovascular disease, and does not recommend it for anyone at high risk of cardiovascular disease. It advises stopping if pregnancy is suspected, avoiding it with oral naltrexone for alcohol or opioid dependence, and caution in severe kidney or liver impairment, where nausea and vomiting may be worse. Side effects and cost are on the PT-141 overview.