It works for up to 36 hours. An inherited eye disease that affects the retina. Recent heart or blood vessel problems. Its effects might last longer if you have mild to moderate ED. 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. When oral medications might not be safe Check with your health care team before you take any . Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an . CHOOSE BRAND-NAME VIAGRA. The original little blue pill prescribed by doctors for over 20 years. Clinically proven to treat men with erectile dysfunction (ED) Ongoing .