Sildenafil (for ED); Tadalafil (for ED)/Selected Strong CYP3A4 Inhibitors Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Some medicines may slow down how quickly your liver processes sildenafil and tadalafil.

What might happen:

Your blood levels of sildenafil and tadalafil may increase and cause harmful effects.

What you should do about this interaction:

Let your healthcare professional (e.g. doctor or pharmacist) know that you are taking these medicines together and if you are taking sildenafil or tadalafil for erectile dysfunction or a lung disease called pulmonary hypertension. Your doctor may want to change the dose of your sildenafil or tadalafil or change your other medicine.Contact your healthcare professional right away if you experience a painful or prolonged erection, fainting or dizziness, or changes in vision.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Viagra (sildenafil) US prescribing information. Pfizer Inc. September, 2015.
  • 2.Cialis (tadalafil) US prescribing information. Eli Lilly and Company April, 2016.
  • 3.US Food and Drug Administration (FDA). Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers. Available at: http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/D rugInteractionsLabeling/ucm093664.htm. Updated 08/05/2011.
  • 4.This information is based on or an extract from the UW Metabolism and Transport Drug Interaction Database (DIDB) Platform, Copyright University of Washington 1999-2014..