Tadarise 20 mg stays effective in the system for about 36 hours. This drug works by improving the flow of blood that flows into the penis of a man while he is involved in a sexual act. This drug enables a man to have multiple erections in a sex session which makes it one of the most famous drugs in the world. This drug comes in many dosages and should be taken as per the prescription given by the doctor. This oral drug is taken with a full glass of water and is usually taken 30 to 40 minutes before having sex. It is advised to have the entire tablet and not crush it before taking it.