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.Esse metabólito apresenta retrato por seletividade para as PDE semelhante a da sildenafila e potên