This medicine works best when you take it on an empty stomach an hour before sex. You can take this medicine with or without food 30 minutes before sex, depending on the dose. The most common side effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, such as changes in color vision such as having a blue color tinge and blurred vision; stuffy or runny nose; back pain; muscle pain; nausea; dizziness; rash. Generic versions of sildenafil, vardenafil and tadalafil are available. Some people may also have ringing in their ears tinnitus or dizziness. 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. This medication is taken with or without food an hour before sex.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 . 1 day ago · If you’re interested in buying Viagra online, five of the best options available are Hims, Roman, Lemonaid, Optum Store, and REX MD. Read on for full details on the . Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum Missing: usa.