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ED Oral Medications – Phosphodiesterase (PDE) Inhibitors


Treatment of erectile dysfunction (ED) with oral medication is safe reliable and considered first line therapy (usually first treatment or medication that should be used).  Medications classified as Phosphodiestrase inhibitors have become the GOLD STANDARD therapy.  A phosphodiesterase inhibitor is a drug that blocks the enzyme phosphodiesterase (PDE), thereby preventing the inactivation of the intracellular second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) . By preventing the inactivation of those messengers, the levels of both cAMP and cGMP increases inside the penis.  this increase  promotes and sustains an erection.

CIALIS, VIAGRA and LEVITRA are approved PDE medications to treat erectile dysfunction (ED).

Do not take a PDE if you:

  • take medicines called “nitrates” such as isosorbide dinitrate or isosorbide mononitrate which are often prescribed for chest pain as the combination may cause an unsafe drop in blood pressure
  • use recreational drugs called “poppers” like amyl nitrite and butyl nitrite
  • are allergic to CIALIS or ADCIRCA® (tadalafil), or any of its ingredients. Call your healthcare provider or get help right away if you experience any symptoms of an allergic reaction, such as rash, hives, swelling of the lips, tongue or throat, or difficulty breathing or swallowing.
  • Stop sexual activity and get medical help right away if you get symptoms such as chest pain, dizziness, or nausea during sex. Sexual activity can put an extra strain on your heart, especially if your heart is already weak from a heart attack or heart disease.


Are PDE good for everyone?

PDEs are  not right for everyone. Only your healthcare provider and you can decide if PDEs are right for you. Ask your healthcare provider if your heart is healthy enough for you to have sexual activity. You should not take a PDE if your healthcare provider has told you not to have sexual activity because of your health problems. Before taking a PDE, tell your healthcare provider about all your medical problems, particularly if you have or ever had:

  • heart problems such as chest pain (angina), heart failure, irregular heartbeats, or have had a heart attack
  • high or low blood pressure or have high blood pressure that is not controlled
  • stroke
  • liver or kidney problems or require dialysis
  • retinitis pigmentosa, a rare genetic (runs in families) eye disease
  • severe vision loss, including a condition called NAION
  • stomach ulcers or a bleeding problem
  • a deformed penis shape or Peyronie’s disease
  • an erection that lasted more than 4 hours
  • blood cell problems such as sickle cell anemia, multiple myeloma, or leukemia


Can Other Medicines Affect the use of PDEs?

Tell your healthcare provider about all the medicines you take especially if you take:

  • medicines called “nitrates” which are often prescribed for chest pain
  • alpha-blockers often prescribed for prostate problems
  • blood pressure medications
  • medicines for HIV or some types of oral antifungal medications
  • some types of antibiotics such as clarithromycin, telithromycin, erythromycin (several brand names exist, please contact your healthcare provider to determine if you are taking this medicine)
  • other medicines or treatments for erectile dysfunction (ED)
  • PDEs are well known for their trade name but not by their generic name.  CIALIS is Tadalafil, VIAGRA is Sildenafil, while LEVITRA is Verdenafil.  Tadalafil is generic for both CIALIS and ADIRCA, while Sildenafil is generic for both VIAGRA and REVATIO are Sildenafil.  Tadalafil is generic for LEVITRA and STAXYN.  Both ADCIRCA and REVATIO are marketed for the treatment of pulmonary arterial hypertension. Do not take a combination of any PDE!


What Should I Avoid While Taking PDEs?

  • Do not use other ED medicines or ED treatments while taking any PDE.
  • Do not drink too much alcohol when taking PDEs, for example, (5 glasses of wine or 5 shots of whiskey). Drinking too much alcohol can increase your chances of getting a headache or getting dizzy, increasing your heart rate, or lowering your blood pressure.


What Are The Possible Side Effects of PDEs?

The most common side effects with CIALIS are: visual disturbances, headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose. These side effects usually go away after a few hours. Men who get back pain and muscle aches usually get it 12 to 24 hours after taking PDEs. Back pain and muscle aches usually go away within 2 days. Call your healthcare provider if you get any side effect that bothers you or one that does not go away.


What are other uncommon but serious side effects of PDEs?

An erection that won’t go away: If you get an erection lasting more than 4 hours, seek immediate medical help to avoid long-term injury.

In rare instances, men taking prescription ED tablets, reported a sudden decrease or loss of vision or hearing (sometimes with ringing in the ears and dizziness). It’s not possible to determine if these events are related directly to the ED tablets or to other factors. If you have a sudden decrease or loss of vision or hearing, stop taking any ED tablet, including CIALIS and call a healthcare provider right away.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call 1-800-FDA-1088.

PDEs does not:

  • cure ED
  • increase a man’s sexual desire
  • protect a man or his partner from sexually transmitted diseases, including HIV
  • serve as a male form of birth control