If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. Take sildenafil as needed before sexual activity. 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 medicine also works best when you take it an hour before sex on an empty stomach. You can take sildenafil with or without food. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. Use the oral syringe provided with your medication to measure and take your dose.No, you should not take Viagra if you don’t have ED. Viagra is a prescription medication that can have serious side effects. And it’s approved only to treat ED, not to be used. If you are taking sildenafil (Viagra) for ED, do not take it more than once a day. Take an hour before sexual stimulation (range 30 minutes to 4 hours). If you take it with a high-fat . Your prescription may have been filled with a generic version instead of brand-name VIAGRA. Follow the steps below to help ensure you receive the brand name your doctor .