Some people may also have ringing in their ears tinnitus or dizziness. The frequency of patients reporting improvement of erections in response to a global question in four of the randomized, double-blind, parallel, placebo-controlled fixed dose studies patients of 12 to 24 weeks duration is shown in Figure 7. The possible categorical responses to these questions were 0 no attempted intercourse, 1 never or almost never, 2 a few times, 3 sometimes, 4 most times, and 5 almost always or always. Protein binding is independent of total drug concentrations. 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.Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. indigestion (upset stomach) mild vision. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung . The price you’ll pay for sildenafil may vary based on the strength and form of the drug your doctor prescribes for you. The price may also depend on which .