Isosorbide dinitrate and Sildenafil interaction
Isosorbide dinitrate and Sildenafil: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Isosorbide dinitrate label · effective 2020-03-02
Do not use Isosorbide Dinitrate in patients who are taking certain drugs for erectile dysfunction (phosphodiesterase inhibitors), such as sildenafil, tadalafil, or vardenafil.
Concomitant use of Isosorbide Dinitrate with phosphodiesterase inhibitors in any form is contraindicated (see CONTRAINDICATIONS ).
WARNINGS Amplification of the vasodilatory effects of Isosorbide Dinitrate by sildenafil can result in severe hypotension.
From the Sildenafil label · effective 2026-07-17
CONTRAINDICATIONS Administration of SILDENAFIL ORAL FILM to patients using nitric oxide donors, such as organic nitrates or organic nitrites in any form.
SILDENAFIL ORAL FILM was shown to potentiate the hypotensive effect of nitrates.
…its known effects on the nitric oxide/cGMP pathway [see Clinical Pharmacology ( 12.1 , 12.2 ) ] , SILDENAFIL ORAL FILM potentiates the hypotensive effects of nitrates, and its administration to patients who are using nitric oxide donors such as organic nitrates or organic nitrites in any form either regularly and/or intermittently is therefore contraindicated.
After patients have taken SILDENAFIL ORAL FILM it is unknown when nitrates, if necessary, can be safely administered.
Although plasma levels of sildenafil at 24 hours post dose are much lower than at peak concentration, it is unknown whether nitrates can be safely co-administered at this time point [see Dosage and Administration ( 2.2 ), Drug Interactions ( 7.1 ), and Clinical Pharmacology ( 12.2 ) ].
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.