Key takeaways

Muse is a prescription drug for erectile dysfunction that works by widening arteries in the penis, administered as a urethral suppository before sexual activity.
Common side effects include penile pain, urethral burning, minor bleeding, testicular pain, and flu-like symptoms, with serious side effects such as prolonged erections and severe low blood pressure being less common.
To minimize side effects, patients are advised to follow medical directions closely, including proper insertion techniques and not exceeding recommended dosages.
Muse may not be suitable for everyone, especially those with certain medical conditions like heart disease, penile abnormalities, or blood disorders, and interactions with other medications can occur.

Muse is a prescription brand-name drug used for the treatment of erectile dysfunction. Alprostadil, the active ingredient in Muse, widens arteries in the penis to allow more blood flow into erectile tissues to allow for successful sexual intercourse. Muse is administered as a transurethral suppository about 10 minutes before anticipated sexual activity as needed. The suppository is inserted into the urethra with an applicator and the medicine is absorbed into penile tissues through the urethra.

As with all prescription drugs, Muse may not be right for everyone. Side effects are common, particularly relating to problems associated with urethral insertion. Some men may not be able to take the drug because of pre-existing physical or medical issues. However, there are ways to minimize or manage problems when taking Muse.

Common side effects of Muse

Muse is administered as a urethral suppository, that is, it is inserted into the urethra opening at the end of the penis. The most common side effects of Muse are related to this method of administration, such as penile, urethral burning, and minor urethral bleeding. Because the drug is rapidly eliminated in the body, system-wide side effects are less common.

The most common side effects of Muse are:

Penile pain
Urethral burning
Minor urethral bleeding
Testicular pain
Flu-like symptoms
Dizziness
Headache
Back pain
Infection
Pelvic pain
Low blood pressure (hypotension)
Swelling of the leg veins
Rapid pulse

Because the drug is administered into the urethra, a female partner might also experience side effects. In clinical trials, approximately 5.8% of female sexual partners reported vaginal burning or itching.

Serious side effects of Muse

The most serious side effects of alprostadil include:

Prolonged erections (4 or more hours)
Painful erections
Curving of the penis with painful erection
Fainting (syncope)
Severe low blood pressure
Swelling in the testes

Muse and penile pain

Because Muse suppositories are inserted directly into the urethra, many men taking Muse will experience pain or discomfort during or after insertion. Penile pain is the most common, reported by 32% of men in clinical trials. Burning in the urethra was reported by 12% of the patients, testicular pain in 5%, and minor bleeding from the urethra from another 5%. Self-injected alprostadil (Caverject Impulse) also has a high incidence of penis pain—in 37% of men during clinical trials—but can also cause bruising at the injection site in 3% of men. For both Muse and Caverject, these side effects can be discouraging enough to persuade men to discontinue alprostadil treatment for ED. Healthcare providers usually turn to alprostadil treatments only when first-line ED treatment with oral Viagra (sildenafil) or Cialis (vardenafil) is not possible or doesn’t work.

Muse and low blood pressure

Alprostadil can cause blood pressure problems including low blood pressure, high blood pressure, and flushing. In clinical trials, approximately 3% of men taking Muse experienced clinically significant low blood pressure, or hypotension. About 0.4% of men fainted within one hour of administering a Muse suppository. Men taking Muse should watch carefully for signs of low blood pressure after putting in a suppository: dizziness, lightheadedness, and feeling faint. If Muse is causing low blood pressure or fainting, tell the prescribing healthcare provider. Doses may need to be reduced.

Muse and priapism

All ED medications carry a risk for prolonged erections, defined as an erection that lasts longer than four hours. Prolonged and painful erections that last for longer than six hours are a serious medical condition called priapism. Untreated, priapism can do permanent damage to the erectile tissues in the penis. Both prolonged erections and priapism should receive immediate medical attention.

How long do side effects last?

After a Muse dose is administered and absorbed through the urethra, the alprostadil in the dose is rapidly metabolized by enzymes in the urethra and corpus cavernosum. The metabolites are then cleared by the kidneys and liver. With a half-life of five to 10 minutes, the drug’s effects on erections last about 50 to 60 minutes. Most side effects including blood pressure effects, penis pain, testes pain, dizziness, fainting, and headache should clear up by then.

By definition, prolonged erections and priapism last for several hours, but these effects are rare (less than 1%) in people taking Muse. Prolonged erections could, however, permanently worsen erectile dysfunction.

Muse contraindications & warnings

Muse is more likely to cause problems in some people than others. Below we discuss restrictions and interactions in more detail.

Abuse and dependence

The U.S. Food and Drug Administration (FDA) does not consider alprostadil to have a potential for abuse or physical dependence.

Overdose

Although no Muse overdose has been reported, an overdose of Muse could increase the risk of low blood pressure, penis pain, or prolonged erection or priapism. If too much Muse has been administered, contact a poison helpline or get medical help.

Restrictions

Because of potential hazards, Muse can never be prescribed to people with:

Allergies to Muse: Anyone with a history of hypersensitivity to alprostadil or the other ingredients in Muse cannot safely take this medicine.

Penile abnormalities: Alprostadil can worsen penile abnormalities including narrow urethra (urethral strictures), abnormal curvature, penile fibrosis, Peyronie’s disease, abnormal location of the urethral opening (hypospadias), swelling of the glans area at the top of the penis (balanitis), acute or chronic swelling of the urethra (urethritis).

- Penile Implants: Muse has not been studied in patients with penile implants. A potential for drug-device interaction exists.

Sickle-cell anemia, thrombocythemia, polycythemia, leukemia, or multiple myeloma: All of these conditions either make it difficult for blood to flow through blood vessels (hyperviscosity syndrome) or raise the risk for blood clots; both problems make people taking Muse more likely to experience prolonged erections or priapism.
Heart disease: Sexual activity is considered a vigorous physical exercise that increases heart rate. Some men cannot safely engage in sexual activity because of this added strain to the heart. If the risks from sexual activity are too great, they cannot get a prescription for Muse or any other ED medication.

Patients should avoid activities such as driving or hazardous tasks where injury could result if dizziness or syncope were to occur after the administration of Muse.

Men with low blood pressure can take Muse but may need to be given a lower dose. People with bleeding disorders may be at risk of prolonged bleeding from inserting the urethral suppository, so extra caution is required when using the Muse urethral applicator.

Pregnancy

Although Muse is never prescribed to women, men who are using Muse must use a condom when having sex with a pregnant woman. In men taking Muse, alprostadil can be found in their ejaculate. As a prostaglandin, a common protein found in the body, alprostadil has many effects. Among those effects, prostaglandins can induce uterine contractions and labor. Therefore, Must should not be used for sexual intercourse with a partner who is pregnant unless a condom barrier is used.

Children

The FDA has not approved Muse for use in children.

Seniors

People older than 65 can take Muse in the same doses as younger adults. However, seniors are more at risk for serious cardiovascular events brought on by vigorous activity such as sexual intercourse. All patients young and old prescribed erectile dysfunction medications will need a thorough evaluation of their heart health.

Muse interactions

Alprostadil is a short-lived drug, lasting only an hour or so in the body. Drug interactions, then, tend to be minimal and mild compared to other ED medications.

Still, alprostadil can cause low blood pressure, so healthcare professionals will be cautious about combining alprostadil treatment with drugs that lower blood pressure or widen blood vessels (vasodilators).

Some over-the-counter antihistamines and decongestants can cause or contribute to erectile dysfunction, so they can significantly reduce the effectiveness of ED medications. Men taking Muse might consider skipping medications containing antihistamines or decongestants like cold remedies, allergy medications, or sinus medications on days they’re going to use Muse. Alcohol also contributes significantly to erectile problems, so drinking may not be a good idea.

How to avoid Muse side effects

For people using Muse, body-wide side effects, such as low blood pressure, headache, or fainting, tend to be short-lived. On the other hand, the most common complaints people have with Muse involve issues and problems with inserting the transurethral suppository. Some men quit taking Muse because of these problems. There are ways, however, to minimize side effects, particularly insertion problems.

1. Tell the healthcare provider about all medical conditions and medications

Most people don’t realize that side effects—especially the worst ones—are often due to how drugs affect already-existing physical conditions. The surest way to avoid side effects with any prescription medication is to give the healthcare provider a complete medical history. This history should include all the prescription drugs, over-the-counter medicines, and even dietary supplements that are regularly taken. For Muse, the prescribing healthcare provider particularly needs to know about:

Heart disease
Blood pressure problems (high or low blood pressure)
Blood problems (such as sickle cell anemia or leukemia)
A type of bone marrow cancer called multiple myeloma
Penis abnormalities
A penile implant
A history of prolonged (> 4 hours) erections
Any advice given by a doctor to avoid sexual activity

2. Take Muse as directed

Take the dose as prescribed by a healthcare professional. Read, understand, and follow the patient information that comes with the medicine. Do not increase or decrease the dose. If it doesn’t seem to be working or side effects are a problem, the prescribing healthcare provider may be able to adjust the dose.

3. Don’t overdo it

Do not insert more than two Muse suppositories in a 24-hour period. Each pellet contains one dose (125, 250, 500, or 1000 mcg). Unfortunately, Muse does not always produce an adequate erectile response. If two suppositories taken on the same day don’t work, wait until the next day.

4. Insert Muse suppositories as instructed

A healthcare provider will administer the first dose and teach you how to use the applicator safely to insert a Muse pellet. It’s important to understand and follow these directions to avoid insertion side effects. Furthermore, dose titration should only be carried out under medical supervision.

5. Stretch the penis to full length before inserting the applicator

A healthcare provider will show you how to prepare the penis for insertion. It is important that the penis be gently pulled or stretched to full length so that the urethra is straight when the applicator is inserted. Getting this wrong may cause pain or bleeding.

6. Be careful when separating the suppository from the applicator

A healthcare provider will show you what to do after injecting the pellet, including a wait time and gently rocking the applicator to separate it from the pellet. This is very delicate and requires care. If it’s done incorrectly, the applicator tip can scratch the urethra and cause pain or bleeding. Always keep the penis straight when removing the applicator.

7. Roll the penis from side to side after inserting a suppository

Urethral burning is a common side effect after inserting a Muse pellet and it’s caused by the urethral tissues being irritated by the medicine. The burning is worse if the medicine is concentrated in one spot. A healthcare provider will demonstrate how to roll the penis between the hands to distribute the medicine along the urethra. If the urethra starts to burn, it may take 30 to 60 seconds of gentle rolling to distribute the medicine.

8. Be well-rested and relaxed

All prescription medications involve a balance between benefits and side effects. One way to successfully manage side effects is to maximize benefits. A healthcare provider will counsel patients on several tips and methods on achieving and maintaining erections, but the best medical advice is to be relaxed and well-rested. Anxiety, tiredness, stress, and drinking alcohol all contribute to erectile dysfunction. In those cases, the risk of side effects remains the same, but the benefits could be zero.

9. Store this medicine correctly

To realize the full benefits of this medicine, keep Muse pellets in their original foil pouch in the refrigerator (between 2°- 8°C) until ready for use. Muse pellets can be stored in their foil pouch at a cool room temperature (below 30°C) for 14 days, but heat will ruin the medicine. Do not expose Muse pellets to temperatures above 30°C.

Resources

Alprostadil, StatPearls
Alprostadil compound summary, U.S. National Library of Medicine
Alprostadil drug summary, Prescriber’s Digital Reference
Caverject Impulse prescribing information, U.S. National Library of Medicine
Muse, Epocrates
Muse package label, Paladin Labs, Inc.
Muse prescribing information, U.S. National Library of Medicine