Fildena Professional contains sildenafil, it can interact with several medicines. The most important ones are: Nitrates — do NOT combine: medicines such as nitroglycerin, isosorbide mononitrate, or isosorbide dinitrate, often used for chest pain. The combination can cause a dangerous drop in blood pressure. Riociguat — do NOT combine: another medicine used for certain types of pulmonary hypertension. Alpha-blockers: such as doxazosin or tamsulosin can cause additional blood-pressure lowering, dizziness, or fainting. Fildena Professional -pressure medicines: including amlodipine, may further lower blood pressure. Certain antibiotics/antifungals and HIV medicines: erythromycin, ketoconazole, itraconazole, and especially ritonavir can increase sildenafil levels and its side effects. Other erectile-dysfunction medicines/PDE5 inhibitors: combining them with sildenafil is not recommended. If you give me the names of all medicines or supplements you currently take, I can check them specifically against Fildena Professional.