Caverject (Alprostadil)

How does it work?

Caverject injections contain the active ingredient alprostadil, which is a type of medicine called a prostagladin.

Alprostadil is the same as a naturally occurring chemical called prostaglandin E1. This prostaglandin is thought to cause some types of blood vessels to widen by relaxing the thin layer of muscle found in the blood vessel wall.

An erection is produced via a complex chain of events, involving signals from the nervous system and the release of active chemicals, including prostaglandin E1 within the tissues of the penis. These chemicals cause blood vessels entering the penis to widen, allowing more blood to enter, and other blood vessels leaving the penis to constrict, stopping blood from leaving the penis.

Prostaglandin E1 plays an important role in this process and alprostadil, when administered directly into the penis, will ultimately cause the penis to become rigid and erect by increasing the blood flow into its tissues. An erection usually occurs between 5 and 15 minutes after injection. The dose injected determines how long the erection will last for.

What is it used for?

  • Impotence (erectile dysfunction).
  • Aid to diagnosis of erectile dysfunction.

How do I use it?

  • Caverject injections are administered by injection directly into the penis. Your doctor will teach you the correct technique for doing this. It is important to follow your doctor's instructions and the instructions provided with the injections.
  • Re-constituted solutions of alprostadil are for single use only. Any remaining solution should be discarded carefully, as instructed by your doctor, and not be kept for a second injection.
  • Do not use this medicine more than once a day, or more than three times a week.


  • If your erection lasts longer than four hours (priapism), consult a doctor immediately. Treatment of this condition should not be delayed more than six hours, as this can cause damage to the erectile tissue in the penis and irreversible erectile dysfunction.
  • While you are using this medicine you should have regular check-ups with your doctor so they can check for any signs of fibrous tissue formation in your penis.
  • This medicine will not protect you or your partner from sexually transmitted diseases. Using a condom can provide this protection. This is particularly important since the injection can cause bleeding, which increases the risk of disease transmission.

Use with caution in

  • Men with blood clotting disorders or taking anticoagulant medicines such as warfarin.
  • Heart disease.
  • Heart failure.
  • History of small temporary strokes (transient ischaemic attacks).
  • Lung disease.
  • History of psychiatric illness.
  • History of drug dependence or abuse.

Not to be used in

  • Conditions in which sexual activity is not advisable, for example severe heart disorders.
  • Conditions such as sickle cell disease, bone marrow cancer or leukaemia in which there is an increased risk of prolonged erections (priapism).
  • Men with physical abnormality of the penis, such as severe curvature, scarring or Peyronie's disease.
  • Men who have an implant in their penis.
  • Women.
  • Children.

This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

  • This medicine can be used by couples wishing to conceive and with a partner who is pregnant or breastfeeding.
  • If your partner is pregnant it is recommended that you wear a condom during sex, because this medicine may add to the levels of prostaglandin E1 found naturally in semen. This could potentially irritate the vagina and carry a risk to the foetus.
  • This medicine will not prevent pregnancy. If you and your partner don't want to conceive you will need to use a reliable form of contraception.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Very common (affect more than 1 in 10 people)

  • Pain in the penis.

Common (affect between 1 in 10 and 1 in 100 people)

  • Blood clots which form a solid swelling at the injection site (haematoma).
  • Leg cramps.
  • Prolonged erection.
  • Formation of fibrous tissue within the penis.
  • Abnormal angulations of the erect penis.
  • Scarring of the penis.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

  • Bleeding, inflammation, irritation, swelling, numbness, tenderness or warmth at the injection site.
  • Dilated pupils.
  • Feeling sick.
  • Dry mouth.
  • Weakness or loss of strength (asthenia).
  • Blood in the urine.
  • Urgent need to pass urine.
  • Pain when passing urine.
  • Increased heart rate.
  • Decreased blood pressure (hypotension).
  • Fungal infections.
  • Persistent painful erection of the penis (priapism).
  • Inflammation of the end of the penis (balanitis).
  • Contraction of the foreskin (phimosis).
  • Pain in the testicles, scrotum or pelvis.
  • Swelling of the testicles or scrotum.
  • Abnormal ejaculation.
  • Rash, sweating or itching.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start using this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while using this one, to make sure that the combination is safe.

This medicine should not be used with any other medicines for erectile dysfunction.

People taking medicines to prevent blood clots (anticoagulants such as warfarin or heparin) may have an increased risk of bleeding after the injection.

Alprostadil may enhance the effects of medicines that decrease blood pressure. If you are taking a blood pressure lowering medicine this medicine may make you feel dizzy after the injection. If you experience this you should sit or lie down until the symptoms pass. Medicines that can decrease blood pressure include the following (some of these may be taken for reasons other than high blood pressure):

  • ACE inhibitors such as enalapril, captopril
  • aliskiren
  • alpha-blockers such as doxazosin, tamsulosin
  • angiotensin II receptor antagonists such as losartan, valsartan
  • beta-blockers such as atenolol, propranolol
  • calcium-channel blockers such as diltiazem, nifedipine
  • clonidine
  • diazoxide
  • diuretics such as bendroflumethiazide, furosemide
  • hydralazine
  • methyldopa
  • minoxidil
  • moxonidine
  • nitrates such as amyl nitrate (poppers), glyceryl trinitrate, isosorbide mononitrate.

Other medicines containing the same active ingredient

Viridal Duo MUSE