The current trial is recruiting newly diagnosed adults who have not yet received treatment. Approximately 270 participants will be randomly assigned to take up to 75 milligrams of amitriptyline or a placebo each day for 14 to 26 weeks. All participants will be given techniques to practice suppressing the urge to urinate for increasingly longer stretches until they can wait 3 or 4 hours before going to the bathroom. Participants will also regulate when and how much they drink and avoid bladder irritants such as alcohol, acidic foods and carbonated or caffeinated drinks. Staff and patients will find out who received the amitriptyline when the study is finished. Medications and tests are free to participants.