Root canal treatment is mainly indicated to relieve the pain from a deep cavity which can not be restored by normal filling methods. Some individuals might have a slight discomfort after RCT, which is usually bearable and less intensity than your previous complaint. Your endodontist/Dentist would recommend antibiotic and pain killer for 3 to 5 days to manage this discomfort after RCT. But gum swelling after RCT is not a normal phenomenon, if there is a swelling (Periapical abscess) we have to wait and after it resolves only we have to obturate (Fill and close the root canals of the tooth) and complete the RCT.  kindly check this Educational video and click this to know how we perform RCT. Kindly check some other myth and facts of RCT.