This allows the smooth muscles in the penis to relax and fill with blood. Your doctor may adjust your dose if needed. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. Some platforms have a digital pharmacy that ships the medication to your home, while others send an electronic prescription to your local pharmacy. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. Do not press on the plunger of the syringe.Side Effects. Dizziness, headache, flushing, or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision, or trouble telling blue and green colors apart may. VIAGRA can be safe for some seniors. Patients over the age of 65 should start with only half a regular dose of VIAGRA, according to Pfizer Medical Information. The typical starting dose of VIAGRA is 50 mg, but older men may need to start at 25 mg. Also, seniors tend to have underlying conditions that could put them at risk of adverse . Hims sells a chewable ED medication consisting of sildenafil, the active ingredient in Viagra. BlueChew only sells one medication that contains sildenafil, which combines with tadalafil.