Extra Super Avana side effects of Avanafil can be mild to severe and may include blurred vision, dizziness, nausea, stomach pain, numbness, or vomiting. In some cases, a person may develop an allergic reaction to the drug, which can cause a sudden stinging sensation and swelling of the mouth or face. These symptoms should be reported to a doctor immediately. Other less serious side effects of Avanafil include blurred vision, lightheadedness, headache, and diarrhea.