Read our editorial process. Erectile dysfunction can be caused by a variety of factors , including age, cardiovascular problems, diabetes, and other conditions that affect nerve function or blood flow. Especially tell your healthcare provider if you take any of the following: medicines called nitrates medicines called guanylate cyclase stimulators such as Adempas riociguat medicines called alpha-blockers, such as Hytrin terazosin HCl , Flomax tamsulosin HCl , Cardura doxazosin mesylate , Minipress prazosin HCl , Uroxatral alfuzosin HCl , Jalyn dutasteride and tamsulosin HCl , or Rapaflo silodosin. Please expect up to 4 to 6 weeks for reimbursement. Those with pre-existing conditions should always consult a healthcare provider before taking new medications or supplements.Viagra, Cialis, Levitra, and Stendra are oral medications for treating erectile dysfunction. Check out side-by-side comparisons of all four drugs. Gemstone illustration by Emil Hochdanz. CC0. minanebgaf. February 19, “I’ll just step over to Green Gables after tea and find out from Marilla where he’s gone and why,” the worthy woman finally concluded. “He doesn’t generally go to town this time of year and he never visits; if he’d run out of turnip seed he wouldn’t. Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken as needed about 1 hour.