Zudena pills contains avanafil, not udenafil. Udenafil is another medication used to treat erectile dysfunction. Typically takes about 30-60 minutes to work. May include headaches, flushing, nasal congestion, and back pain. Typically takes about 30-60 minutes to work. If you’re considering either medication, it’s essential to consult with a healthcare provider to determine the best option for your needs and to understand potential side effects and interactions.