Alprostadil (Intracavernosal)

Alprostadil for injection, or intracavernosal injection therapy, is a drug that adult men can take for erectile dysfunction, or ED.


Alprostadil is a drug for ED that is available by prescription. It comes in a suppository form as well as a form for intracavernous injection, but the injection is more effective in achieving an erection. During the intracavernous injection therapy process, a small amount of the medication is injected directly into the penis. The medication acts as a muscle relaxer and blood vessel dilator. Once the patient administers the injection, within up to thirty minutes, the penis should be firm enough to engage in sexual intercourse.

Alprostadil is a prostaglandin (PGE-1), which is a medication that relaxes certain muscles in the penis. It also causes blood vessels in the body to expand. With this combination of muscle relaxant plus blood vessel dilation, the blood vessels can expand to allow more blood to flow freely throughout the body. These two effects working together allow blood to flow to the penis and cause an erection.

Alprostadil is a medication that should be taken only by adult men who are experiencing ED. In the injection form, it is important to follow all the instructions, because, if it is not used properly, permanent damage to the penis may result. The patient's doctor will demonstrate how to properly prepare the medication and the syringe, how to inject the drug into the penis and how to achieve the best effects from using this medication.

Alprostadil usually begins to work in a very short time - about five to twenty minutes from the time that the patient injects the medication into the penis. Before having sexual intercourse, a patient should wait for about 10 to 30 minutes, in order to give the medication time to work and reach sufficient strength. After waiting for the appropriate amount of time, a patient using Alprostadil should have an erection firm enough for sex. This erection is likely to last for about an hour, and can sometimes last for an additional period of time after ejaculation.

Conditions treated

  • Sexual impotence
  • Other conditions as directed by a doctor

Type of medicine

  • Prostoglandin (PGE-1)

Side effects

All drugs may cause side effects, depending on the individual patient. However, with Alprostadil, most of the men who use this medication will have no side effects or only have minor side effects. In some cases, the side effects listed below for Alprostadil will not need medical attention, and should subside within a short amount of time. A doctor may be able to address how to reduce or avoid some of these side effects. Some of the minor, less common side effects include the following:

  • Dizziness
  • Headache
  • Penile pain or painful erection at any time
  • Bleeding and pain at the site of the injection (which should subside after a few minutes)

There are some rarer side effects from taking Alprostadil for injection as well. If the patient experiences any of these, he should check with his doctor immediately. One such side effect is the curving of the penis. This can be a serious condition, and may indicate that there is a problem with the blood vessels. Any stinging in the urethra, as well as any bleeding or spotting, can also indicate a severe problem for which attention should be sought right away.

One serious side effect is an erection that lasts four to six hours. This is an abnormal result and can indicate a serious problem. Usually this type of extended erection is also accompanied by severe pain in the penis. If the penis does not return to normal non-erect position for a time period of this duration, it is important that the patient seek medical attention immediately. If immediate medical help is not sought, it is possible that long term damage could occur, including losing the ability to achieve an erection entirely.

Other rarer side effects include any pain or swelling in the testes after the injection or during intercourse, as well as the appearance of any bruised spots or clotted blood which might appear at the injection site on the penis. This type of bruising or discoloration may indicate that the injection was not correctly applied. A patient should contact his doctor before repeating a dose.

As with any medication, some patients may experience other side effects which are not listed here. If there are any other side effects or pain symptoms which are not listed above, patients should contact their healthcare professional immediately.

In addition to talking to their doctor for medical attention, patients may also report any side effects to the FDA at 1-800-FDA-1088.


The Alprostadil injectable dosage is for adult men. Dosages will be different among patients, and the treating physician will determine for each patient what the best dosage will be. In order to make sure the correct dose has been prescribed, the first dose is administered in a doctor's office, and the patient will have to remain in the doctor's office until his erection subsides. Patients should follow their doctor's instructions, or review the instructions on the medication packaging and label.

The average adult dose of Alprostadil for injection for treating erectile dysfunction is 1.25 to 60 micrograms (mcg), taken as a single dose. It can be used once a day, or otherwise as determined by a doctor. A patient should not inject more than a single dose in any 24-hour period. Patients should also avoid using this medication for more than two consecutive days, or more than three days in a given week.

This medication is injected directly into the patient's penis as demonstrated by the doctor, and should be administered 10 to 30 minutes before the patient intends to have sexual intercourse. It takes 5 to 10 seconds to inject the full dose. Specific instructions will be included with the injection medication. Patients should real all instructions carefully before use.

Alprostadil injection therapy is not recommended for women or children, and should not be taken by anyone who does not have ED.

For the injection form, there are several Alprostadil products that are available on the market. The method of injection will be the same for each, but the mixing instructions may be different. All of the medications that are on the market will come with the proper solution required to mix with the powder. Only the supplied solution should be used for preparation of the medication.

Before the patient draws the solution into the syringe, there are general steps to take for preparing the solution. Injectable Alprostadil is sold as a powder in a vial, and must be mixed with a sterile liquid solution which will be provided with the product. This solution for mixing the with the drug powder may be pre-loaded into the syringe the patient will use, or it may be provided in a separate vial.

Since there are multiple injectable brand name products, it is important that a patient know which of the different products they will be using, and carefully following the proper mixing instructions specifically provided for that product. The patient's doctor can provide brand-specific information, as can the product packaging, which includes complete instructions.

The patient should wash hands thoroughly with soap and water before preparing the solution. The bottles should be placed on a clean surface, and the top wiped with an alcohol swab. Dispose of the swab. Patients should not wipe the syringe needle. Depending on the product, the needle may need to be attached to the syringe. Do not take the cap off yet.

Once the solution has been mixed according to the manufacturer instructions, the method for drawing the medication into the syringe is the same for all products. The steps are as follows:

  • The patient should make sure the solution is clear. If there is any visible matter or any solids in the solution, or if the solutions appear to be cloudy or colored, the medication should not be used.
  • Once the Alprostadil solution has been mixed, insert the needle into the Alprostadil bottle. Using one hand, the bottle and the syringe should be turned upside down together as a single unit. The tip of the needle should be covered by the solution. Using the other hand, the patient should slowly pull the plunger backwards, which will draw the solution into the syringe. Pull the plunger until the correct dose of the medication is in the syringe, and check the dose by holding the syringe at eye level to see the dosage scale on the side of the syringe.
  • After checking the dose, the patient should look for air bubbles. If there are any visible air bubbles in the syringe, they can be removed by tapping gently on the scale side of the syringe. This will move the bubble to the top of the syringe.
  • If a reading of the dosage shows there is not enough medication, then more of the solution should be drawn until the correct dose is reached. Likewise, if too much has been drawn out, pushing the syringe plunger will return medication to the bottle. Check until the exact dosage fills the syringe.
  • Holding the barrel of the syringe (not the plunger), pull the needle from the bottle.
  • At this point, the cover should be put back on the needle. The syringe is now ready to be used to inject a dose.

A patient should follow the steps below to administer their Alprostadil injection:

  • Select the spot on the penis for the injection, as directed by the doctor.
  • Use an alcohol swab to clean the injection spot. While sitting, the patient should hold his penis steady against the thigh, to avoid movement while administering the injection.
  • Take the cover off the needle and place the needle at a 90 degree angle to the injection spot.
  • Inject the needle into the selected spot on the penis, until nearly the entire metal portion of the needle has been inserted.
  • Using the plunger, press slowly for 5 or 10 seconds to inject the medication into the penis.
  • When the dose has been fully inserted, withdraw the needle, and replace the cap on the needle.

Once the injection is complete, the patient should put pressure at the point of the injection for approximately 5 minutes, or until bleeding, if there is any, stops. The patient should massage his penis to ensure the medication is spread to all areas of the penis. When prescribing this medication, the doctor will provide instructions for doing this properly.

It is important to avoid injecting the drug improperly in any of the following ways: inserting the needle just beneath the skin surface, into the head of the penis or at the top, or at the base of the penis near the testes or the scrotum. Do not inject directly into any visible blood vessels.

This injection should not be painful, but if the patient finds it is painful, or if there is any bruising, redness or swelling at the injection point, the patient is probably injecting the drug under the skin. The patient should stop injecting the medication, remove the needle and place it at the proper angle before he continues to administer the medication.

Each time a patient uses Alprostadil for injection, he should select a different spot for the injection in order to avoid skin problems. For example, he might alternate sides of the penis for injection each time he uses the medication.

Major drug interactions

Using Alprostadil for injection with the following medicines is usually not recommended, but may be necessary in some cases with the recommendation of a doctor. Where a doctor recommends that both medicines be used together, they may modify the dose or frequency of the medication to help avoid unwanted side effects. Below is a list of some of the medications known to interact with Alprostadil for injection:


If a patient is taking this medication, he should inform his doctor prior to taking Alprostadil for injection.

In addition to the above medication, certain interactions could occur when using alcohol or tobacco products. There is also the possibility of an interaction with certain over the counter drugs, including herbal and dietary supplements. Patients should inform their doctor of all of these products prior to using Alprostadil for injection.


Alprostadil for injection should only be used if recommended by a doctor, based upon a patient's personal medical history and needs. During the appointment, a patient should be sure to inform his doctor of any of the following:

  • If he has had a prior allergic reaction to any form of Alprostadil.
  • If he is allergic to any drugs that are similar to this one, or is allergic to any other medications, foods, or any other substances. The doctor will need to know more about the allergy and the symptoms the patient has with the allergy, which could include a rash, hives, itching, swelling of face, lips, tongue, or throat, shortness of breath, wheezing, cough, or any other signs.
  • Any other prescription medications or over the counter drugs, as well as herbal remedies and dietary supplements
  • Whether he has a penile implant, a deformed penis, or other penile issues.
  • If he has a history of priapism, which is a condition in which the patient has experienced painful or continuing erections that are not the result of sexual arousal.
  • If he has polycythemia (a condition in which the patient has excessive red blood cells) or thrombocythemia (a condition in which there are increased number of platelets in the blood).
  • If he has any of the following health problems: leukemia, multiple myeloma, sickle cell anemia, or other health problems that could cause the possibility of having a painful erection or an erection that lasts for longer than 4 hours. The patient should discuss with the doctor if he is unsure.
  • If the patient has previously been told by a health professional that he is not healthy enough to have sex.

A patient should not take Alprostadil injections if has a penile implant, without first discussing with his doctor.

Patients should not take more doses of this medication than is prescribed. This drug should not be taken more than once every two days, and not more than three times in a week. If the patient injects too much of this medication, or takes it more frequently than prescribed, the patient may have an erection that lasts too long without subsiding. This is what is known as priapism, and can lead to serious and permanent damage to the penis if not treated immediately. Patients experiencing priapism should contact their doctor immediately in cases where their erection lasts longer than four hours, or if it is painful.

If there is continued bleeding at the injection point after the needed is withdrawn, the patient should apply pressure to stop the bleeding. If after five minutes the bleeding continues, a doctor should be consulted. With continued bleeding, it is possible to transmit illness or infection to a sexual partner.

Alprostadil for injection is intended only to treat ED, and does not prevent pregnancy. Patients should use a form of birth control to avoid pregnancy. In addition, if the patient is having sex with a woman who is or may be pregnant, it is recommended that the patient use a condom to avoid contact between the medication and the fetus. It is not known what the effects of Alprostadil is on an unborn fetus.

Alprostadil for injection does not provide any protection from contracting sexually transmitted diseases (STDs). In addition to birth control, it is recommended that a patient use condoms or other recognized methods to protect against contracting STDs.


Alprostadil for injection can be stored in the refrigerator or at room temperature. It should not be frozen.

This medication in a powder form may be kept at room temperature (15 to 25 °C or 59 to 77 °F) for up to three months. Once the powder has been mixed into a solution, the solution is best used right away, but can be used within 24 hours, so long as it is not refrigerated or frozen.

As with all medications, this drug should be kept where children cannot reach it.

Any medications that are past their expiration date or no longer being used should be disposed of properly. A healthcare professional or law enforcement professional can provide instructions for proper disposal.


Alprostadil in the injection form is a medication used for treating ED (also referred to as sexual impotence) in men. Alprostadil is a type of prostoglandin medication. Prostoglandins work by both relaxing certain muscles in the penis and also expanding blood vessels. When injected directly into the penis, Alprostadil increases blood flow to the penis, which causes an erection.

Alprostadil should only be used by men with ED. If it is used by individuals who do not have a medical need to take it, it can result in serious physical damage, including permanent damage to the penis, as well as losing the ability to have erections altogether. It is not recommended for children or for women.

Alprostadil for injection is prescribed in a powder form, and the product includes the correct solution for mixing. One the patient mixes the medication, it should be used immediately. The solution is then injected directly into the penis using a syringe. Approximately thirty minutes following the injection, the patient should achieve an erection firm enough for sexual intercourse, which can last for an hour, or sometimes longer.

Some of the common side effects are bleeding at the injection site, pain in the penis or a painful erection, dizziness or headache. Rarer side effects, which can be more serious, are curving of the penis during the erection, severe pain or swelling in the testes or penis, a severely painful erection, bleeding that does not subside after a few minutes, stinging, spotting or bleeding from the urethra, or an erection lasting more than four to six hours. If any of these serious side effects occur, immediately medical attention should be sought. Failure to seek immediate medical attention can result in permanent damage to the penis or to the ability to achieve an erection.

The patient should inform the doctor of certain conditions he has prior to using Alprostadil, as well as whether he is using drugs that are similar to Alprostadil and any other medications or supplements. Allergies to foods or any other substances are also a potential concern, so the patient should inform their doctor of the symptoms they have had, including rash hives itching, swelling of the face, shortness of breath or wheezing, or any other signs. Patients should always inform the doctor of all other prescription medications and over the counter drugs they are taking, along with herbal remedies or dietary supplements.

A patient may not be a candidate for the Alprostadil injection if he has a penile implant, a deformed penis, or any other similar penile issues. Most importantly, a history of priapism, or painful erections which can last four to six hours, may also mean that the patient should avoid using this medication.

Last Reviewed:
December 10, 2017
Last Updated:
April 04, 2018
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