Zudena 100 mg is typically taken once per day. Taking more than one dose in a 24-hour period is not recommended as it can increase the risk of side effects. Remember, Zudena 100 mg will not cause an erection without sexual stimulation. It works in response to arousal, so it’s important to be sexually stimulated for the medication to be effective. Zudena 100 mg tablet should be taken about 30 to 60 minutes before sexual activity. This gives the medication enough time to start working and to increase blood flow to the penis when sexually stimulated. Udenafil works by increasing blood flow to the penis, helping men achieve and maintain an erection during sexual activity.