Stendra 50 contains a generic drug called Avanafil with a dosage of 50mg. It is an FDA-approved and doctor-prescribed drug used to get relief from erectile dysfunction problems. Stendra 50mg is the lowest dosage, which is often prescribed when the higher strengths are causing you problems with side effects. The common side effects of Stendra 50 include headache, dizziness, flushing, etc. It is advised to consult a doctor for directions and dosage before practicing any medication.