Avaforce 50 has a relatively fast onset of action, often within 15 to 30 minutes after ingestion. The effects of Avaforce can last for up to 4 to 6 hours, providing a window of opportunity for sexual activity. Like any medication, avanafil-containing drugs may have side effects. Common side effects include headache, flushing, nasal congestion, back pain, and dizziness. If you experience persistent or severe side effects, it's important to contact your healthcare provider.