Contact your doctor immediately if this occurs. Read our full article on the topic: What to do if your ED medication isn’t working. Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. 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. We recommend taking the medication exactly as prescribed, eating healthy, reducing alcohol and cigarette intake, and maintaining adequate exercise. It is not all in your head, and lifestyle choices may contribute to ED. 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.The maximum dose of Viagra is mg each day. Doses above the maximum dose, such as mg per day, will increase the risk of side effects. And in . VIAGRA is available by prescription only in 25 mg, 50 mg, and mg tablets. Not actual size. TIPS FOR TAKING VIAGRA Take VIAGRA exactly as your doctor tells you to take .  · For oral dosage form (tablets): Adults up to 65 years of age—50 milligrams (mg) as a single dose no more than once a day, 1 hour before sexual intercourse. Alternatively, the medicine may be taken 30 minutes to 4 hours before sexual .