Zudena is a brand name for the medication sildenafil, which is used to treat erectile dysfunction (ED). It’s similar to Viagra, as both contain sildenafil as the active ingredient. Zudena pills work by increasing blood flow to the penis, which helps achieve and maintain an erection. Typically, it starts to work within 30 to 60 minutes after ingestion. For best results, it’s recommended to take it on an empty stomach, as a high-fat meal might delay its absorption and effectiveness.