Tadalafil: Drug Interactions & Contraindications

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson is going to go over the important contraindications of tadalafil. You'll also learn about some example drug interactions of note for this medication.


Although you may know tadalafil as Cialis, a medication used to treat erectile dysfunction (impotence), tadalafil is actually used for a lot more! It's used to improve exercise tolerance by treating high blood pressure in the lungs and to manage the signs and symptoms of BPH, benign prostatic hyperplasia.

Just like this medication has so many varied uses, it also has a lot of varied contraindications and drug interactions. That's what this lesson is about.


Let's begin with the contraindications. What are these? Well, you literally just learned about three of tadalafil's indications, its uses. Contraindications are thus times when this drug shouldn't be used.

The first major contraindication to tadalafil's use is a known hypersensitivity to the medication or any other ingredients used to make the pill. What hypersensitivity is referring to is an allergy-like reaction to the medication. What could a hypersensitivity reaction to tadalafil look like? Well, there's more than one possibility but it could manifest itself as a fever with a very painful rash and blisters, something known as Stevens-Johnson syndrome.

Another important contraindication to tadalafil is the concurrent use of medications known as nitrates or guanylate cyclase stimulators. Nitrates, like nitroglycerin, are medications that help treat things like angina, which is chest pain stemming from a problem with the heart. Guanylate cyclase stimulators, like riociguat, can be used to treat high blood pressure in the lungs. Since all three, tadalafil, nitrates, and guanylate cyclase stimulators cause drops in blood pressure independently, using two or more at the same time can lead to dangerously low blood pressure.

Drug Interactions

As you have probably surmised by now, the last two contraindications are also examples of important drug interactions between tadalafil and another drug. But they're not the only ones. Tadalafil has literally hundreds of drug interactions your doctor would have to consider prior to giving you this medication. Let's go over a few other ones:

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