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. 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. That means eating healthy foods, exercising, getting good sleep, limiting stress, and treating other health conditions that might cause ED, like high blood pressure, heart disease, diabetes, obesity, and low testosterone, Dr. Patients should always ask their doctors for medical advice about adverse events. If you have an erection that lasts more than 4 hours, get medical help right away. Pearlman says it can often take months to get an appointment with a healthcare provider who can prescribe the medications commonly used to treat ED. But, some side effects, including flushing, heartburn, sinus congestion, and headaches, might prevent some men from taking them even though they work well.Is there anything over the counter that works like Viagra? Many over-the-counter (OTC) treatments, including herbal supplements, claim to be able to treat ED, but none of these options are. 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. A person may also wish to consider making some lifestyle changes instead of using Viagra. What is the closest thing to Viagra over-the-counter? There are no over-the-counter alternatives to Viagra.