Over half of all Canadian men struggle with being able to get (or keep) an erection — aka erectile dysfunction — yet fewer than 25% of them choose to do anything about it. Not only is it common, but it’s easy to treat.

There are several oral medications available for treating erectile dysfunction (ED) and deciding which one is best comes down to personal preference. To help you choose which ED medication is best for you, we break down how they work, what the different types are, and important things to consider.

Here’s the long and short of it…

How it works

ED medications are from a drug family called phosphodiesterase type 5 inhibitors (or PDE5 inhibitors for short). PDE5 inhibitors affect the smooth muscle cells lining the blood vessels in the penis. Basically they block your body’s “off switch” — the PDE5 — from bringing your erection to an end. Tadalafil (Cialis) and Sildenafil (Viagra) both do this, but their onset and duration of action differ.

Tadalafil (Cialis)

Tadalafil is a longer-acting medication. It lasts for an average of 36 hours, and can be taken as a single daily dose or an “on demand” dose. For example, if you know you’ll be having sex on the weekend, you could take your Tadalafil on a Friday night and be covered for a couple of days. Because of this, Tadalafil is often known as the “weekend” ED medication. The recommended starting dose for on demand use is 10 mg every 2–3 days, decreasing to 5 mg if side effects, or increasing to 20 mg if needing more effect.

Some people prefer the simplicity of a 5 mg daily dose instead. The benefit to this approach is that you never have to think about whether you’ve taken a pill or not.

Sildenafil (Viagra)

If you don’t mind taking a medication right before sex, Sildenafil is a great option. This quick-acting medication is ideally taken on an empty stomach one hour before sex and will remain active in your system for about four hours.

The initial dose should be 50 mg, and it should be reduced to 25 mg if side effects occur. If, on the other hand, it’s well tolerated, but the erectile response is not adequate, the dose can be increased to 100 mg.

Side effects with Tadalafil and Sildenafil are similar, and can include facial flushing, runny nose, headache, nausea or indigestion.

Safety First

  • Don’t use nitrates with your ED medication. This includes nitro spray or the nitro patch (used to treat heart disease and angina), as well as recreational drugs like poppers or alkyl nitrates. They can cause severe low blood pressure.

  • If you ever develop an erection longer than 3 hours, please go to the emergency department. This is a rare, but dangerous, side effect called priapism.

  • Tadalafil and Sildenafil shouldn’t be taken together, as it increases the risk of side effects.

  • Very rarely these medications can cause a change in vision or blindness called ischemic neuropathy, which can be irreversible. Go to the emergency department if you experience visual changes while on ED meds.

It’s best to know your personal preferences around taking an ED medication, as it will help your doctor prescribe the right one for you. And if you’re still unsure, the Felix doctors are here to help you make that decision so you can take the stress out of sex.

This isn’t rocket science. Well, it is, sort of.

This article was co-authored by Dr. Kelly Anderson, Felix Medical Director.


No content on this site should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

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