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Last updated February 27, 2020. 2 minute read

What are common side effects of ED medication?

Oral medications for ED are very effective. Like all drugs, they also come with the potential for side effects, which can range from mild to severe, and dangerous drug interactions.

Self Written by Michael Martin
Reviewed by Mike Bohl, MD, MPH

Oral medications for ED are very effective. Like all drugs, they also come with the potential for side effects, which can range from mild to severe, and dangerous drug interactions. Here’s what to expect, and where you should exercise caution before beginning ED treatment.

What is erectile dysfunction?

The malady formerly known as impotence, erectile dysfunction (ED) is the inability to get or maintain an erection sufficient for satisfying sex. That might include erections that don’t last as long as you want or aren’t as firm as you’d like. ED is very prevalent among American men: Experts estimate that more than 30 million American men have experienced these kinds of erection issues (Nunes, 2012).


  • ED medications known as PDE5 inhibitors (e.g., Viagra, Cialis) work by blocking a chemical that allows blood to flow out of an erect penis.
  • That process can have a few side effects, including flushing, upset stomach, and headache.
  • ED drugs can have serious interactions with prescription medications or recreational drugs that lower blood pressure.
  • Talk with a healthcare provider about other medical conditions you might have or other medications you’re taking before starting treatment for ED.

What medications are used to treat ED?

ED medications are known as phosphodiesterase type 5 (PDE5) inhibitors. They include sildenafil (brand name Viagra), tadalafil (brand name Cialis), avanafil (brand name Stendra), and vardenafil (brand names Levitra and Staxyn). These medications work pretty much the same way: by blocking the chemicals (called PDE5) that allow blood to leave an erect penis.

When PDE5 is blocked, the smooth muscle within the walls of blood vessels stay relaxed, and blood flows more freely throughout the body, including to the penis.


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What are some of the side effects of ED medication?

That sequence of events can come with a few potential side effects. The most common side effects of erectile dysfunction medications include:

  • Flushing
  • Upset stomach, heartburn or indigestion
  • Headache
  • Sensitivity to light (objects may seem to have a blue tinge)
  • Runny nose or nasal congestion
  • Body aches, including back pain

Less common side effects of ED drugs include priapism (an erection that lasts longer than four hours and won’t go away), vision loss, and changes in hearing.

Why does ED medication have side effects?

Sildenafil (the active ingredient in Viagra) was originally developed as a blood pressure medication. (Erections were originally just a “side effect” of the original hypertension medication.) That’s why Viagra can cause dangerously low blood pressure, especially if you’re already taking high blood pressure medication.

Tell your healthcare provider about other medical conditions you have, especially if you’re taking drugs like nitrates or recreational “poppers” that can lower blood pressure.

Serious side effects of ED medication

Go to the emergency room immediately if you experience any of the following symptoms or side effects:

  • Chest pain
  • Shortness of breath
  • Severe headaches
  • Fainting
  • Erections that last longer than four hours
  • Visual changes (like loss of sight)
  • Or anything out of the ordinary—even lightheadedness

If you notice any severe or prolonged symptoms at all, contact a healthcare provider immediately. It doesn’t matter how rare a side effect is if you’re the one experiencing it.

Each ED medication has its own unique drug interactions and side effects that you should be aware of when choosing the right treatment. Talk with your healthcare provider to choose the best treatment based on your medical history, symptoms, and preferences.