PT 141: Is this novel ED treatment safe?

Erectile dysfunction (ED) is a lot more common than you might think, affecting up to a third of men at some point in their lives.1 Not only does it prevent them from enjoying intercourse with their partners, but it also creates a tremendous amount of shame and anxiety.2 There are myriad causes for ED, from stress and fatigue to medications and obesity.

Fortunately, there are just as many ways to treat ED, though some are better established than others. Prescription drugs like Viagra and Cialis are among the most well-known and effective, and various nutritional supplements claim to work similarly. PT 141 takes a more unconventional approach that appears to offer efficacy but with a greater risk of side effects than equally useful alternatives. It isn’t a pill like Viagra or Cialis; its delivery method is either a nasal spray or a subcutaneous injection.

It’s also nowhere near as well-known by the general public, which is why we created this guide to familiarize you with its potential and safety profile.

PT 141 is an injectable liquid — sometimes delivered as a nasal spray — that some men look to as a potential treatment for ED. In recent years, the FDA approved a version of PT 141 — branded Vyleesi — to treat female hypoactive sexual disorder. No such prescription is available for men. Currently, the only accessible PT 141 outside a Vyleesi prescription comes from scientific research suppliers and is labeled as not suitable for human consumption. As such, we do not recommend its use in men at this time.

PT 141 works as a melanocortin receptor agonist. It binds to receptors in the body typically responsible for control over pigmentation, among other things. One of those other things, it turns out, is erectile performance. It’s also only available in prescription form for women to treat female hypoactive sexual disorder. For men, the only accessible PT 141 comes from scientific research suppliers and is labeled as not suitable for human consumption.

PT 141 gained traction in the early 2000s as a potential treatment for erectile dysfunction while researchers tested potential sunless tanning agents. Regular erections occurred in trials, with the duration of erection increasing along with the dose and consistently outperforming placebos. This led researchers to conclude there was a connection between one of the tanning agents — melanotan II — could function as a treatment for ED.

In the years that followed, researchers isolated bremelanotide — a peptide from melanotan II — that they believed was the primary driver of the erection side effects. This peptide, which is also called PT 141, then entered trials to treat erectile dysfunction.3 Early trials were mostly successful, but it took nearly 20 years for the drug to gain FDA approval and hit the market in any form. However, Vyleesi, the approved medication, is a form of bremelanotide intended for premenopausal women to treat hypoactive sexual disorder. The FDA has yet to approve a version of the drug to treat ED.4

The reasons for this long wait are somewhat unclear, but it may be telling that the company that initially developed PT 141 — King Pharmaceuticals — was acquired by Pfizer in 2010. Pfizer famously manufactures Viagra, and they may have had a vested interest in keeping PT 141 off the shelves until after Viagra’s patent expired in 2020. A close look at the research into PT 141 for sexual function shows a noteworthy gap between 2007 and 2019.

PT 141 is a cyclic heptapeptide melanocortin analog. That means it’s a synthetic version of a natural chain of seven amino acids, and it activates melanocortin receptors without the tanning effects that were the goal of early melanotan II trials. The exact pathophysiology involved in the melanocortinergic system resulting in an erection is currently unclear. A comprehensive paper on the topic delves into several potential mechanisms of action, but much more research is needed to understand the nuances of PT 141’s ability to improve sexual function.

Theoretically, by acting on the brain instead of the circulatory system, PT 141 could serve as a substitute ED medication for men with heart or blood pressure issues that prevent them from taking PDE-5 inhibitors like Viagra.10 Typical PDE-5 inhibitors widen blood vessels, which is great for getting more blood to the penis but also lowers blood pressure enough that doctors require a recent blood pressure reading before prescribing them.

PT 141 takes a little longer to work than the typical PDE-5 inhibitor, even at high doses. Those higher doses (10-20mg) often fail to produce erections that last as long as one produced with a PDE-5 inhibitor. Some purveyors of PT 141 cite studies that demonstrate some men experience erections lasting several hours, but that research was conducted in healthy males without ED.

It’s worth noting that, while a recent bremelanotide study in women showed negligible effects on blood pressure, the FDA halted early research into the drug in its intranasal form due to blood pressure issues. One could assume that the subcutaneous formulation currently approved by the FDA for use in treating female sexual dysfunction doesn’t pose the same risks as intranasal delivery might, but studies comparing them directly would be needed. And as of today, no form of PT 141 delivery — subcutaneous or intranasal — is approved for use in men.

Researchers have mostly looked at PT 141 administered as a subcutaneous injection or a nasal spray.11 The nasal spray is the far more convenient delivery method, and it tends to produce milder side effects (though the FDA halted intranasal PT 141 research in 2007 due to blood pressure concerns, and they’ve only granted approval for subcutaneous delivery). Intranasal delivery also requires slightly higher doses than the injections. That makes the nasal spray more expensive per use than the injectable peptide.

The chart below illustrates the potential benefits of PT 141, but it also shows the significant risk of adverse effects. Success is measured by duration of erection, which is a similar measure used in studies looking at PDE-5 inhibitors. You’ll also notice that it takes 2-3 times the dosage for the nasal spray to be as effective as the subcutaneous injection.

For this chart, an erection is defined as having at least 60% rigidity as measured by RigiScan.5

PT 141 studies are not extensive enough to draw definitive conclusions about its safety. Still, the studies that have been conducted point toward significant issues with flushing, nausea, and vomiting.

Side effects from PT 141 were generally more severe in its subcutaneous injection form than its nasal spray. That said, both had rates of adverse reactions that do not bode well for their overall safety. Its injection and nasal spray saw the following side effects with increasing frequency and intensity at higher dosages:

• Nausea
• Tastes disturbance
• Headache
• Vomiting
• Feeling hot
• Somnolence (excessive drowsiness)
• Flushing
• Back pain
• Diaphoresis
• Fatigue
• Muscle cramps
• Dark urine
• Blurred vision
• Pounding in the ears
• Yellow eyes and skin

The most concerning side effect was delayed-onset vomiting associated with higher doses of the subcutaneous injection. Study subjects who experienced this adverse effect often vomited 6-15 hours after administration. This indicates a toxicity level that implies more significant danger with long-term use. Vomiting was significantly less common with the nasal spray and only at the highest dose.

When you look at the field of research that has gone into PDE-5 inhibitors like sildenafil and tadalafil, it’s clear that those products have a pronounced research advantage over PT 141. With that much more data, the safety of PDE-5 inhibitors is well-established. There are still too many unknowns and too many red flags in PT 141 research to assume it’s safe. It certainly requires a discussion with your doctor first, which is why PT 141 is available for human consumption only via prescription.

The FDA approved an injectable version of PT 141 for women in 2019.13 Branded Vyleesi, this drug is intended to treat hypoactive sexual dysfunction in premenopausal women. It is not approved for use by men in the treatment of ED. Whether there is anything about Vyleesi’s specific formula that would make it safer to use is unclear, but the company’s website lists most of the same potential side effects as those seen in studies of Pt 141.

Several studies support PT 141’s potential as an ED treatment,5 particularly for men who may have heart or blood pressure conditions that prohibit them from taking specific PDE-5 inhibitors like sildenafil (generic for Viagra)6 or tadalafil (generic for Cialis).7 There is also potential for PT 141 to act in conjunction with PDE-5 inhibitors, but this would require much more research than currently exists.8

Most studies on PT 141 took place in a short span of time between its discovery in 2003 and 2007, and research has slowed in the time since. Its efficacy is apparent, but the window of effectiveness in ED patients (the period of time the treatment would allow men to reliably achieve an erection) could not compete with sildenafil’s average four-hour duration. PT 141 shows a typical half-life of 2-3 hours compared to sildenafil’s 3-5 hours.9 Vyleesi suffers from the same diminished half-life, lasting women around two hours. But as there is no equivalent to sildenafil, Vyleesi is the best available option for women.

PT 141 is only available by prescription as Vyleesi, so there is no prescription approved for men hoping to use PT 141 for ED. There are basically two pathways to acquiring PT 141 for men who are determined to get it: companies that sell scientific research products and some online men’s health clinics that deal in the periphery of what's medically safe and acceptable.

Scientific research sites explicitly state that PT 141 is not intended for human consumption and should only be used for research purposes. Still, a glance at their customer reviews shows that individuals purchase and take the peptides themselves, ignoring the site’s disclaimers. And there are rarely reliable ways to verify the content and purity of what they’re shipping to you unless you also happen to be a scientist.

The other sites at least try to provide a safety net and a resource to contact in the event of adverse reactions. They have doctors on staff who will give you an off-label prescription for PT 141 in order for you to buy it through the site. These are not necessarily reputable companies, however. None of the most trustworthy telehealth companies — including legitimate general medical providers like Lemonaid and Nurx, as well as those specializing in ED treatments like BlueChew or Hims — deal in peptides.

Online sources for PT 141 that offer prescription services also bear a significant markup for their nasal spray and injectables. Take a look at the cost per dose of PT 141 from an average seller compared to sildenafil or tadalafil from BlueChew:

*Providers will often compound nasal sprays based on prescribed strength. Most spray bottles contain eight administrations, the recommended maximum for one month. The cost per dose of the nasal spray is based on ⅛ the price of a bottle.

**Tadalafil will not create an erection that lasts for 36 hours, but it allows sexual arousal to result in an erection as needed for up to 36 hours.

Given the safety concerns, side effect profile, accessibility challenges, and high cost, we don’t recommend PT 141 for the vast majority of men who have trouble achieving an erection. We understand the allure — a “peptide” sounds more natural and innocent than a pharmaceutical drug may sound, though PT 141 is synthetic — but that’s not enough to justify the risks or costs associated with it.

Our recommendation

Instead of opting for a riskier, more expensive, and less effective medication, we recommend starting your ED treatment journey with something proven safe and effective. Sildenafil and tadalafil are among the most effective and well-researched treatments available. And with modern telemedicine, you can receive a prescription from a board-certified physician and have your medication shipped discreetly to your home in a matter of days. No ED treatment route is more private and discreet than this.

Our top recommendation for ED treatment is BlueChew. Having the ability to consume a chewable tablet without water up to 36 hours before sexual activity is undeniably convenient. Because the pills come in individual packets, you can carry one with you on dates or when you travel. BlueChew also lets you take advantage of a one-month free trial of ED medication (either sildenafil or tadalafil). This is a good value for men who have never tried these medications.

If you’re curious about BlueChew, you can read all about it, and its free trial is exclusive to Innerbody readers in our comprehensive review. You can also learn about other ED treatment options in our complete ED treatment guide.

At Innerbody Research over the past two decades, we have helped tens of millions of readers like you make more informed decisions to live healthier lives. Our research and experience in the men’s sexual health space is particularly expansive.

For this guide to PT 141, we utilized hundreds of hours of ED research, including the thorough review of nearly 100 scholarly articles about male sexual function in general and erectile dysfunction in particular. We spoke with men who use popular ED treatments and their partners to assess their levels of satisfaction, and we experienced the ordering processes from the top providers in the space.

Additionally, like all health-related content on this website, this assessment of PT 141 was thoroughly vetted by one or more members of our Medical Review Board for accuracy. We will continue monitoring developments about PT 141 to keep our readers informed and up-to-date.

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