When you take Zudena, which contains udenafil, it is primarily used to treat erectile dysfunction (ED). The effects usually start within 30 minutes to an hour after taking the pill and can last for several hours. Zudena pills works by relaxing blood vessels, which increases blood flow to the penis when you are sexually aroused, helping to achieve and maintain an erection. Many men find that it helps them engage in sexual activity more successfully, but individual responses can vary. It’s important to take Zudena under the guidance of a healthcare provider, especially if you have underlying health conditions or are taking other medications.