Oral Medications to treat erectile dysfunction include Viagra, Cialis, Levitra and Stendra. They belong to the class of Phosphodiesterase-5 (PDE-5) Inhibitors.

More information about your medication:

Tadalafil (Cialis), Sildenafil (Viagra, Revatio), Vardenafil (Levitra), Avanafil (Stendra)

How does a PDE-5 Inhibitor work?

Phosphodiesterase Type 5 is an enzyme that leads to relaxation of smooth muscle. In the penis, it initiates the relaxation of an erection. PDE-5 inhibitor medications block this enzyme and, by so doing, affect erectile function. These medications DO NOT initiate erections. Rather, they allow erections to occur in response to stimulation. It is advised to take these medications 30-60 minutes before sexual activity, but may also be taken as a daily, low dose therapy to improve erectile dysfunction symptoms. Take your medication as directed at today’s visit. PDE-5 Inhibitors are not only for symptom relief; they may, over the long term, contribute to improved penile vasculature. When used correctly, PDE-5 Inhibitors work in 7 out of every 10 men with erectile dysfunction, and in patients of any age or race.2 In addition to vascular causes, neurogenic, psychogenic, or endrocrinologic factors may also contribute to erectile dysfunction. Because of this, reducing stress, anxiety, and depression may also improve erectile dysfunction symptoms.

Possible side effects of PDE-5 inhibitors include, but are not limited to:

  • Headache
  • Flushing
  • Nausea
  • Nasal Congestion
  • Myalgia (muscle aches)
  • Back pain
  • Abnormal vision
  • Priapism (prolonged erection >4 hours)

Instructions for using Viagra, Levitra, Cialis, Stendra, Sildenafil

  • Take medications around 1 hour prior to sexual activity.
  • These medications are amplifiers, Not "magic pills"- you must have sexual stimulation for them to work.
  • They often do not work the 1st time, so you need to try at least 4 times before you decide if they do or do not work for you.
  • Especially for Viagra, take the pills prior to a meal or after a light snack. They do not absorb well if you have a full stomach.

DO NOT TAKE THESE MEDICATIONS IF YOU ARE ON NITROGLYCERIN OR MEDICATIONS WITH NITRATES OR EVEN HAVE NITROGLYCERIN AT HOME.

THESE MEDICATIONS DO NOT PROTECT YOU AGAINST SEXUALLY TRANSMITTED DISESASE.

We will be discussing your response to this new medication at your scheduled follow-up visit. Should you have any questions or concerns in the meantime, do not hesitate to contact your provider at (801) 213-4961, or through the MyChart communication system. If you experience severe side effects, including changes in vision, please contact 801-587-1454. If you develop an erection lasting longer than 4 hours, seek immediate medical attention.

  1. Selvin E, Burnett A, Platz E. Prevalence and risk factors for erectile dysfunction in the US. American Journal of Medicine. 2007 Feb;120(2):151-157.
  2. Urologic Care Foundation. Treating erectile dysfunction: Medical options. Official Foundation of the American Urologic Association. 2014 April.

PDE-5 Inhibitors

Sexual stimulation leads to the production of nitric oxide in the penis. Nitric oxide then activates the enzyme, guanylate cyclase, which causes the production of cGMP. The cGMP helps calcium leave the cell and results in muscle relaxation, which helps start and maintain an erection by increasing the amount of blood coming into the penis. PDE5 inhibitors inhibit an enzyme called phosphodiesterase-5 (PDE5), which destroys the cGMP; therefore, PDE5 inhibitors prevent the destruction of cGMP and allow cGMP to persist longer. The longer cGMP persists, the easier it is to get and keep an erection.

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