Nitrates are medications that dilate blood vessels and are given to men with certain types of heart disease. When nitrates interact with PDE5i they can cause dangerous drops in blood pressure. Some men take daily nitrates (e.g. isosorbide dinitrate). Other men carry nitrates, which means they only take a nitrate if they experience chest pain. The problem is that they don’t know when they will have chest pain. If a PDE5i is taken and then the patient experiences chest pain, he will be stuck in a situation where he needs a nitrate but will have a drop in blood pressure if he takes it. For that reason, any man who takes or carries nitrates should never take PDE5i.
Some medications for treating symptoms related to an enlarged prostate (such as terazosin or alfuzosin) can cause slight decreases in blood pressure. Men who are on these medications should not take them within 4 hours of taking a PDE5i; otherwise the combination can result in dizziness or lightheadedness.
Antiretroviral medications for HIV, sometimes referred to as HAART medications, can increase the likelihood of side effects (such as headache and facial flushing) of PDE5i. For this reason, men on HAART medications often start with lower doses of PDE5i.
For a full list of drugs that interact with sildenafil please see the Prescriber’s Digital Reference (PDR).
This information is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment, and should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.