The most common Unwanted effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, like adjustments in colour eyesight (for example getting a blue shade tinge) and blurred vision; stuffy or runny nose; back discomfort; muscle mass soreness; nausea; dizziness; rash.are allergic to sildenafil, as contained in VIAGRA and Revatio®, or any… Read More