Fildena 100 is a very effective medicine for treating erectile dysfunction. The main ingredient in this drug is sildenafil. This drug increases blood flow to the muscles in the penis. This medicine should be taken orally. You should take this medicine as advised by your doctor. You can take this medicine 30 to 40 minutes before intercourse. This medicine should be taken only once a day, if more than one medicine is taken it has proved to be more effective. The drug is usually taken 30-40 minutes before and lasts for 5-7 hours.