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Side Effects of Erectile Dysfunction Drugs

Friday 30 November 2018

Table of Contents

I. Most common side effects

II. Viagra

III. Levitra

IV. Cialis

V. Can side effects be avoided?

VI. Affordable erectile dysfunction drugs?

Most common side effects

Erectile dysfunction drugs have helped millions of men and made it more acceptable to openly discuss the condition. But like all medication, ED drugs can come with unwanted symptoms. There are several common side effects of erectile dysfunction drugs, but they’re well tolerated by most men. 

Viagra, Cialis, and Levitra each contain different ingredients, but they all work in the same way. By inhibiting an enzyme called PDE-5, these drugs increase blood flow and make it easier to achieve an erection. There are some side effects that commonly occur in all oral erectile dysfunction drugs, including:

  • Headaches: This is the most commonly reported side effect in all three drugs.
  • Facial flushing: Dilated blood vessels in the head can result in flushing that makes the face feel warm and look red.
  • Nasal Congestion: ED drugs lead to an increased amount of nitric oxide (NO) in the body, which can dilate vessels in the nasal cavities.
  • Gastrointestinal: Various GI symptoms including Indigestion and nausea can occur with all oral ED medications.  

A black and white photo of a woman holding her forehead


Aside from the most common reactions, Viagra can cause changes to the eyes and vision.

  • In addition to PDE-5, Viagra also slightly inhibits PDE-6, an enzyme present in the eyes’ photoreceptors. Sensitivity to light and blurred/blue-tinged vision are the most commonly reported side-effects.
  • Men with eye conditions may be cautioned away from using Viagra and prescribed a different drug to treat erectile dysfunction.


Levitra also inhibits PDE-6, and can cause visual side-effects like:

  • Color distortions
  • Increased eye pressure
  • Sensitivity to light 


Cialis is a longer-acting PDE-5 inhibitor that stays in the body for about 36 hours. Although longer-lasting Cialis may be better for a spontaneous sex life, it tends to lead to more prolonged side effects, like:

  • Pain: A possible side effect of all three drugs, Cialis is more likely to cause pain in the back, muscles, and extremities.
  • Unlike Viagra and Levitra, it’s uncommon for Cialis to have any effect on vision or the eyes.   

Can side-effects be avoided?

There isn’t necessarily anything men can do to avoid these common side effects. All three of the major erectile dysfunction drugs come in a variety of doses, with side effects usually becoming more common as the dosage is increased. For this reason, your doctor will usually start by prescribing the lowest dose. Even if you don’t notice results, it’s important not to increase dosage without your doctor’s guidance.

Not all ED drugs work for every man, and they won’t all cause the same side effects. A man who experiences persistent headaches with Viagra might find that Cialis is a better fit. And someone who has back pain on Cialis may be more comfortable taking Levitra. Prescriptions between these drugs aren’t interchangeable, so you’ll have to ask your doctor about writing a new script if you experience disruptive side effects.

Blue pills in a box

Affordable Erectile Dysfunction Drugs

No matter which drug you’ve been prescribed, you’re probably paying more than you’d like to, and might even find yourself rationing doses. CanadaMedPharmacy.com provides both brand-name and generic erectile dysfunction drugs at lower prices than a traditional pharmacy. Click here to search for your prescribed drug and dosage, and medications will be conveniently and discreetly delivered to your door.

DISCLAIMER: The content in this article is intended for informational purposes only. This website does not provide medical advice. In all circumstances, you should always seek the advice of your physician and/or other qualified health professionals(s) for drug, medical condition, or treatment advice. The content provided on this website is not a substitute for professional medical advice, diagnosis or treatment.