The usual adult dose is 20mg taken 3 times a day. Doses for children can range from 10mg to 20mg taken 3 times a day, depending on their weight. For sildenafil to work properly, you’ll need to be sexually excited. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. How and when to take sildenafil It’s important to take sildenafil as advised by a doctor or pharmacist. In some patients, the use of VIAGRA with alpha-blockers can lead to a drop in blood pressure or to fainting medicines called HIV protease inhibitors, such as ritonavir Norvir , indinavir sulfate Crixivan , saquinavir Fortovase or Invirase , or atazanavir sulfate Reyataz some types of oral antifungal medicines, such as ketoconazole Nizoral and itraconazole Sporanox some types of antibiotics, such as clarithromycin Biaxin , telithromycin Ketek , or erythromycin other medicines that treat high blood pressure other medicines or treatments for ED VIAGRA contains sildenafil, which is the same medicine found in another drug called REVATIO. For erectile dysfunction, it’s best to take sildenafil on an empty stomach. · Viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. You may take it up to 4 hours before sexual activity. Other drugs may interact with sildenafil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here. Sildenafil drug. 7 Over The Counter Medications for ED. Depending on the cause of erectile dysfunction, the most effective treatment can vary. Typically, the best way to treat erectile dysfunction is to address the underlying cause. Second is by using oral medications like Viagra® (sildenafil), Cialis® (tadalafil), or Levitra® (vardenafil), all of which are. Unlike pills like Vigrx Plus which are designed to work over a period of weeks / months, Extenze is a fast acting male enhancement alternative to viagra that works quickly, usually within 45 – 60 min. The original makers of Extenze actually got in a bit of trouble back when they first started selling it.