The information provided here is meant to give you a general idea of what to expect from each of these medications. Only the most common side effects are included, so ask your healthcare provider if there are any precautions specific to your case. Use each of these medications as recommended by your doctor or according to the instructions provided with the medication. If you have further questions about usage or side effects, contact your doctor.

There are 3 types of medical treatments available for erectile dysfunction (ED): pills, urethral inserts, and injections.

Prescription Medications

  • Sildenafil
  • Vardenafil
  • Tadalafil
  • Avanafil
  • Alprostadil    
  • Transurethral alprostadil
  • Intracavernosal alprostadil
  • Sildenafil

    Sildenafil was developed to treat heart disease, but during its clinical trials the subjects noticed they were having erections. Sildenafil works best between 1 and 2 hours after taking it. Sexual function improves by a factor of 3 to 4; 4 out of 5 patients taking the drug report improvement. Sildenafil has been shown to be effective in ED associated with diabetes, spinal cord injury, and medications used to treat depression.

    In contrast to the other agents listed below, sildenafil does not produce an erection in the absence of sexual stimulation. It merely enhances the response. Take sildenafil about an hour before planned sexual activity.

    Sildenafil should not be used in the following conditions:

  • Recent heart attack or stroke
  • Heart failure
  • Concurrent use of nitrate
  • Concurrent use of other medications for erectile dysfunction
  • Hereditary retinal disorders, such as retinitis pigmentosa
  • Sildenafil should be used with caution in the following:

  • Liver or kidney failure
  • Bleeding disorders
  • Ulcer disease
  • Heart disease
  • Concurrent use of blood pressure medications, especially alpha-blockers
  • The elderly
  • Sildenafil must be obtained by prescription. There is important information your doctor needs to know about your health before the medication is prescribed.

    Possible side effects include:

  • Headache
  • Flushing
  • Indigestion
  • Visual disturbances, a condition known as nonarteritic anterior ischemic optic neuropathy (NAION) that can cause sudden blindness
  • Drug interactions
  • Vardenafil, Tadalafil, and Avanafil

    These newer drugs have the same efficacy, safety profile, and cost effectiveness as sildenafil. However, the following are major differences you should be aware of:

  • Food, especially fatty food, can delay the absorption of sildenafil, vardenafil, and avanafil, but not tadalafil.
  • The duration of action of these drugs are different:     
  • 4 to 5 hours for sildenafil, vardenafil, and avanafil
  • Up to 36 hours for tadalafil
  • Alprostadil

    There are 2 types of alprostadil:

  • Transurethral alprostadil
  • Intracavernosal alprostadil
  • Alprostadil acts directly on the blood vessels in the penis to cause an erection. It can be inserted into the urethra (urinary tube in the penis) with a special device or injected with a small needle. Erection occurs in 8-10 minutes and lasts 30-60 minutes. The injection is effective in about 65%-85% of users; the insert is effective in about 65%. The maximal number of injections per week is 3.

    Possible side effects include:

  • Lightheadedness
  • Low blood pressure
  • Pain in the penis
  • Problems from the injecting needle
  • Prolonged, painful erection (priapism) (0.4% of users)
  • Bleeding in patients on blood thinners
  • Special Considerations

    Follow these general medication guidelines:

  • Take your medication as directed. Do not change the amount or the schedule.
  • Do not stop taking prescription medication without talking to your doctor.
  • Do not share prescription medication.
  • Ask what results and side effects to expect. Report them to your doctor.
  • Some medications can be dangerous when mixed. Talk to a doctor or pharmacist if you are taking more than one medication. This includes over-the-counter medication and herb or dietary supplements.
  • Plan ahead for refills so you don’t run out.
  • When to Contact Your Doctor

    Contact your doctor if any of the following occur:

  • A side effect that troubles you
  • Priapism (prolonged, painful erection)—This condition can be dangerous. If 4 hours have passed and your penis still has not relaxed, seek emergency medical care.
  • Warning About Medications Not Prescribed by Your Doctor

    Use caution and talk to your doctor before taking any over-the-counter medications for impotence. Some of them may be unsafe.