Megalis 20 Tablet is used to treat erectile dysfunction in men.Megalis 20 Tablet may be taken on an empty stomach or with a meal. It should be strictly taken as advised by your doctor. The medicine will only help you to get an erection if you are sexually stimulated. You should take it about one hour before you plan to have sex. The amount of time it takes to work varies from person to person, but it normally takes between 30 minutes and one hour. Only take it if you need it and it has been prescribed to you by a doctor.