Do not start these medications while taking sildenafil without discussing it with your healthcare provider. Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. You are encouraged to report adverse events related to Viatris products by calling U. Tell your doctor or pharmacist if you are taking nitrates medications for chest pain such as isosorbide dinitrate Isordil , isosorbide mononitrate Monoket , and nitroglycerin Nitromist, Nitro-Dur, Nitrostat. Sildenafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. Your doctor will tell you not to take sildenafil if you are taking street drugs containing nitrates.from $ for 10 tablets 25 mg sildenafil oral tablet from $ for 30 tablets 50 mg sildenafil oral tablet from $ for 15 tablets mg sildenafil oral tablet from $ for . VIAGRA is available by prescription only in 25 mg, 50 mg, and mg tablets. Not actual size. VIAGRA does not protect you or your partner from getting sexually transmitted diseases, including HIV—the virus that causes AIDS. This Savings Offer is limited to 50% savings off the amount of your co-pay or your out-of-pocket cost. Maria Hudson. 4 hrs. ago. Anna Nelson. 6 hrs. ago. David Muldon. 8 hrs. ago.