Sildenafil pill treats erectile dysfunction, a medical condition in which a man is unable to achieve a strong erection when the penis is sexually stimulated. Fildena 150 relaxes blood vessels and helps increase blood flow to muscles. It is advised to take this medicine one hour before planning intercourse to improve your sex life. The drug can also be used on an empty stomach so that the effect of the drug can be felt very quickly. The effect of this medicine usually lasts for 3 to 4 hours.