Hydralazine and Sildenafil Interaction
Drug interaction information between Hydralazine and Sildenafil.
Hydralazine and Sildenafil have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Hydralazine and Sildenafil. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Both drugs work to relax blood vessels, and taking them together can cause your blood pressure to drop to a dangerously low level.
FDA Label Information
7 DRUG INTERACTIONS 7.1 Phosphodiesterase Inhibitors BiDil is contraindicated in patients who are using a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), PDE5 inhibitors such as avanafil, sildenafil, vardenafil, and tadalafil have been shown to potentiate the hypotensive effects of organic nitrates.
Sildenafil Also Interacts With
- Ketoconazole major
- Erythromycin major
- Itraconazole major
- Darunavir major
- Nirmatrelvir/Ritonavir major
Frequently Asked Questions
What SPL severity band is on file for Hydralazine/Isosorbide Dinitrate + Sildenafil?
Compiled FDA labeling labels this pair major. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Sildenafil has 10 labeled pairs on file vs Hydralazine's 2. In the major band specifically: Hydralazine has 2 (also Tadalafil); Sildenafil has 6 (also Ketoconazole, Erythromycin, Itraconazole, Darunavir).
What mechanism field is on file for Hydralazine/Isosorbide Dinitrate and Sildenafil?
Both drugs work to relax blood vessels, and taking them together can cause your blood pressure to drop to a dangerously low level.
Sildenafil carries more major-labeled pairs than Hydralazine
SPL source-record counts only. This page's band is major · classes on file: Hydralazine (Vasodilator / Nitrate Combination); Sildenafil (PDE5 Inhibitor).
Sildenafil has 6 major-labeled pairs vs Hydralazine's 2.
6 major · 1 moderate · 3 minor · 10 total
- Other major peers for Sildenafil
- Ketoconazole
- Erythromycin
- Itraconazole
- Darunavir
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.