Adequate oral intake of the drug helps men stay active for about 4 to 6 hours. For best results, take the Malegra 120 medicine orally with full sexual stimulation 30 minutes before the planned sexual session. Medications for erectile dysfunction are only effective when you are sexually aroused. For impotent men, no arousal means no erection. Familiarize yourself with the medicine before taking it for maximum effectiveness. Some common and less bothersome side effects while taking this high-dose branded drug Malegra 120 include nasal congestion, anemia, headache, back pain, burning sensation, cellulitis, cough, trouble sleeping, gas, or dry mouth.