Zudena 100 mg tablet is a medication used to treat erectile dysfunction. When you take a 100 mg tablet, it works by increasing blood flow to the penis during sexual arousal. It usually starts working within 15 to 30 minutes after taking the tablet. The effects can last for up to six hours, but this can vary by individual. It's important to note that Zudena will not cause an erection without sexual stimulation. Possible side effects can include headaches, flushing, nasal congestion, back pain, or dizziness. Always consult with a healthcare professional before taking any medication for erectile dysfunction to ensure it's safe and appropriate for you.