First Aid and CPR/AED Level C Practice Exam

The key concept is recognizing a dangerous interaction between nitroglycerin and certain erectile dysfunction medications. Nitroglycerin dilates blood vessels by releasing nitric oxide. Some ED drugs, specifically PDE5 inhibitors such as sildenafil, tadalafil, or vardenafil, also boost nitric oxide–mediated vasodilation. When taken together, they can cause a severe drop in blood pressure, which can lead to dizziness, fainting, heart attack, or death. Because of this risk, nitroglycerin should not be given if the person has recently taken an ED medication within about 24 to 48 hours, depending on the drug’s half-life. The other listed drugs don’t create this same acute risk with nitrates, so they don’t require withholding nitroglycerin in the same way.