Megalis 20 mg typically starts working within 30 minutes to 1 hour after ingestion, with peak effectiveness reached within 2 hours. The timing of administration allows the medication to coincide with sexual arousal and readiness. Common side effects of Megalis 20 mg may include headache, flushing, nasal congestion, indigestion, back pain, and muscle aches. These side effects are usually mild and transient. https://www.genericday.com/megalis-20-mg.html