Tadfil 20 mg is not a recognized medication name or brand that I am familiar with. It's possible that it could be a generic name or a brand name specific to a certain region or country. Without more specific information, it is difficult for me to provide accurate details about its characteristics, including its speed of action. However, if you are referring to the medication Tadalafil, which is commonly used to treat erectile dysfunction (ED) and symptoms of benign prostatic hyperplasia (BPH), I can provide some general information. Tadalafil is known to have a relatively long duration of action compared to other similar medications. Tadfil 20 mg can remain effective in the body for up to 36 hours, earning it the nickname "the weekend pill." However, it typically takes about 30 minutes to 1 hour for the effects to start after taking a dose. It's important to note that medication effects can vary from person to person, and factors such as individual metabolism, dosage, and other personal considerations can influence how quickly a medication acts. To get the most accurate and reliable information about a specific medication, it's always best to consult a healthcare professional or pharmacist.