Malegra 25 mg can appear within the first 30 to 60 minutes after taking it, which is around when the medicine starts working. Some effects may also show up later during the next few hours while the medicine is active, since its effect can last about 4 to 6 hours. Common side effects Malegra 25 mg may include headache, flushing, nasal congestion, dizziness, upset stomach, and visual changes. They are usually mild, but the timing can vary from person to person. Get urgent help Seek medical help right away if you get chest pain, an erection lasting more than 4 hours, or sudden vision changes.