Fildena Professional contains sildenafil, so it can interact with several medicines. The most important interactions are: Nitrates — do NOT combine: nitroglycerin, isosorbide mononitrate/dinitrate, and other nitrate medicines. The combination can cause a dangerous drop in blood pressure. Alpha-blockers: medicines such as tamsulosin or doxazosin can cause additional blood-pressure lowering and Fildena Professional when combined with sildenafil. Blood-pressure medicines: sildenafil can add to their blood-pressure-lowering effect; amlodipine is one documented example. Certain antibiotics/antifungals and HIV medicines: drugs that inhibit CYP3A4, particularly ritonavir, can substantially increase sildenafil levels and may require dose adjustment. Other ED medicines/PDE5 inhibitors: combining sildenafil with another ED medicine such as tadalafil or vardenafil is not recommended. If you give me the names of all the medicines you currently take, I can check them one by one for interactions with Fildena Professional.