How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. 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. Box , Mission, KS If your pharmacy does not participate, you may be able to submit a request for a rebate in connection with this Savings Offer. It lasts 4 to 5 hours, or longer if you have mild to moderate ED. Tadalafil Cialis. Vardenafil usually works for 4 to 5 hours. The products discussed in this site may have different product labeling in different countries.Drug Images. What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult . How to Get Generic Viagra – Consumer Reports. An inexpensive blood pressure medication might be an option for some men who suffer from erectile . Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes .