Does Isosorbide Mononitrate Interact With Sildenafil?
Do not use isosorbide mononitrate in patients who are taking certain drugs for erectile dysfunction (phosphodiesterase inhibitors), such as sildenafil, tadalafil, or vardenafil.
Severity: Contraindicated
Severity basis: contraindications section (keywords: do not use). Combining Isosorbide Mononitrate (Nitrate vasodilator) and Sildenafil (PDE5 inhibitor) is classified as a contraindicated interaction.
What to Do
This combination is contraindicated on the FDA label. Do not take these together unless your prescriber explicitly directs it.
How This Interaction Works
Interactions like this one can happen when two medicines have overlapping effects, or when one changes how the other is absorbed, broken down, or cleared from the body. Isosorbide Mononitrate is a nitrate vasodilator and Sildenafil is a pde5 inhibitor; together they are documented as a contraindicated interaction. How much this matters depends on your dose, your other medications, and your overall health.
If You Take Both Medications
If you have been prescribed both Isosorbide Mononitrate and Sildenafil, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.
From the FDA Label
Do not use isosorbide mononitrate in patients who are taking certain drugs for erectile dysfunction (phosphodiesterase inhibitors), such as sildenafil, tadalafil, or vardenafil.
Source: FDA structured product labeling (set_id 06839534-85b8-42aa-b0e3-079ed236be44).
Check these against your full medication list in our free Interaction Checker
Frequently Asked Questions
Can you take Isosorbide Mononitrate and Sildenafil together?
Isosorbide Mononitrate and Sildenafil have a documented contraindicated interaction. This combination is contraindicated on the FDA label. Do not take these together unless your prescriber explicitly directs it.
How serious is the Isosorbide Mononitrate and Sildenafil interaction?
It is classified as a contraindicated interaction, based on the FDA label's contraindications section (keywords: do not use). A contraindicated pairing generally should not be used together.
What should I do if I'm taking both Isosorbide Mononitrate and Sildenafil?
If you have been prescribed both Isosorbide Mononitrate and Sildenafil, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.
This information is educational — not medical advice.
This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.