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.
SildenafilVardenafilTadalafilAvanafilAlprostadil Transurethral alprostadilIntracavernosal alprostadil
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:
strokeHeart failureConcurrent use of nitrateConcurrent use of other medications for erectile dysfunction
Hereditary retinal disorders, such as
Sildenafil should be used with caution in the following: Liver or kidney failureBleeding disordersUlcer diseaseHeart diseaseConcurrent use of blood pressure medications, especially alpha-blockersThe 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: HeadacheFlushingIndigestionVisual disturbances, a condition known as nonarteritic anterior ischemic optic neuropathy (NAION) that can cause sudden blindnessDrug interactions
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 avanafilUp to 36 hours for tadalafil
There are 2 types of alprostadil:
Transurethral alprostadilIntracavernosal 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: LightheadednessLow blood pressurePain in the penisProblems from the injecting needleProlonged, painful erection (priapism) (0.4% of users)Bleeding in patients on blood thinners
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.
Contact your doctor if any of the following occur: A side effect that troubles youPriapism (prolonged, painful erection)—This condition can be dangerous. If 4 hours have passed and your penis still has not relaxed, seek emergency medical care.
Use caution and talk to your doctor before taking any over-the-counter medications for impotence. Some of them may be unsafe.
Erectile dysfunction. National Institute of Diabetes & Digestive & Kidney Diseases website. Available at:
http://kidney.niddk.nih.gov/kudiseases/pubs/ED/index.aspx. Updated November 2015. Accessed March 8, 2016.
Erectile dysfunction. Urology Care Foundation website. Available at:
Updated 2009. Accessed March 8, 2016.
Guay AT, Spark RF, et al. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of male sexual dysfunction: a couple’s problem: 2003 update.
McMahon CN. Treating erectile dysfunction when PDE5 inhibitors fail.
Brit Med J.
Montorsi F, Padma-Nathan H, et al. Erectile function and assessments of erection hardness correlate positively with measures of emotional well-being, sexual satisfaction, and treatment satisfaction in men with erectile dysfunction treated with sildenafil citrate (Viagra).
Sivalingam S, Hashim H, et al. An overview of the diagnosis and treatment of erectile dysfunction.
Webber R. Erectile dysfunction.
Last reviewed March 2016 by Adrienne Carmack, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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