Safety and Efficacy of Dexlansoprazole Delayed-Release Capsules for Healing of Erosive Esophagitis and Maintenance of Healed Erosive Esophagitis and Relief of Heartburn in Adolescents

Inclusion Criteria: 1. In the opinion of the investigator, the participant and parent(s) or legal guardian are capable of understanding and complying with protocol requirements. 2. Prior to any study-specific procedures being performed, the informed consent and the assent form, according to local country requirements, must be signed and dated by parent(s) or legal guardian and by the participant respectively. 3. The participant has a medical history of symptoms of Gastroesophageal Reflux Disease (GERD) for at least 3 months prior to Screening (signed informed consent form and assent, if applicable) as assessed by the investigator. 4. The participant has met the electronic diary qualification criteria as assessed by the electronic daily diary defined as follows: heartburn (burning or hurting in your throat, chest, or stomach) on at least 3 of 7 days.(Note: if an endoscopy done within 1 week of signing informed consent and assent is used to confirm diagnosis of EE, the subject does not need to meet this criterion). 5. The participant has endoscopic evidence of EE (LA Grade A-D) based on the screening endoscopy. 6. The participant is male or female and aged 12 to 17 years, inclusive. 7. A male participant who is nonsterilized and sexually active with a female partner of childbearing potential agrees to use adequate contraception from signing of informed consent and assent throughout the duration of the study and for 30 days after last dose of study medication. 8. A female participant of childbearing potential who is or may become sexually active agrees to routinely use adequate contraception from the time of signing the informed consent and assent until 30 days after the last dose of study medication. Exclusion Criteria: 1. Participant has evidence of cardiovascular, pulmonary, central nervous system, hepatic, hematopoietic, renal, metabolic, endocrine or gastrointestinal disease, or serious allergy, asthma, or allergic skin rash that suggests clinically significant, uncontrolled underlying disease or condition (other than the disease being studied), which may impact the ability of the participant to participate or potentially confound the study results. 2. The participant has a co-existing disease affecting the esophagus (eg, esophageal varices, scleroderma, viral or fungal infection, or esophageal stricture), history of radiation therapy or cryotherapy to the esophagus, caustic or physiochemical trauma such as sclerotherapy to the esophagus. 3. The participant has known history of Barrett's with dysplastic changes in the esophagus. 4. The participant has a known history of eosinophilic esophagitis (EoE) or endoscopic findings suggestive of EoE. 5. The participant has a history of celiac disease or participant tests positive for tissue transglutaminase (tTG) antibody. 6. The participant has active gastric or duodenal ulcers within 4 weeks prior to Day -1. 7. Participant has any finding in his/her medical history, physical examination, or safety clinical laboratory tests giving reasonable suspicion of underlying disease that might interfere with the conduct of the trial. 8. Participant has taken any proton pump inhibitor (PPI) within 1 week (7 days) prior to the Screening Visit. 9. Participant tests positive for H. pylori. 10. The participant has a history of hypersensitivity or allergies to dexlansoprazole or any component of dexlansoprazole or any PPI (including lansoprazole, omeprazole, rabeprazole, pantoprazole, or esomeprazole) or antacid containing Mg(OH)2 and/or Al(OH)3 or simethicone. 11. The participant is required to take excluded medications or it is anticipated that the participant will require treatment with at least one of the disallowed concomitant medications during the study evaluation period as specified in the Excluded Medications and Treatments Section 7.3. 12. The participant has a history of malignant disease (except basal cell carcinoma) within 5 years prior to Screening. 13. The participant has a condition that may require inpatient surgery during the course of the study. 14. The participant requires dilatation of esophageal strictures and/or strictures preventing passage of the endoscope during the Screening endoscopy. Schatzki's ring (a ring of mucosal tissue near the lower esophageal sphincter) is acceptable. 15. The participant is known to be human immunodeficiency virus (HIV) positive. 16. The participant has current or clinical history of Zollinger-Ellison syndrome or other hypersecretory condition. 17. The participant has a history of gastric, duodenal or esophageal surgery except simple oversew of an ulcer. A history of gastric tube and/or percutaneous endoscopic gastrostomy (PEG) placement is allowed. 18. The participant had an acute upper gastrointestinal hemorrhage within 4 weeks prior to endoscopy. 19. The participant has donated or lost ≥300 mL blood volume, undergone plasmapheresis, or has had a transfusion of any blood product within 90 days prior to the first dose of study drug. 20. The participant has a known history of alcohol abuse or illegal drug use within the past 12 months prior to the first dose of study drug. 21. The participant has any Screening Visit 1 abnormal laboratory value that suggests a clinically significant underlying disease or condition that may prevent the participant from entering the study; or the participant has: creatinine \>1.5 mg/dL, alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) \>2 times the upper limit of normal (×ULN), or total bilirubin \>2.0 mg/dL with AST/ALT elevated above the limits of normal values. 22. If female, the participant is pregnant or lactating or intending to become pregnant before, during or within 30 days after last dose of study medication; or intending to donate ova during such time period. 23. If male, the participant intends to donate sperm during the course of this study or within 30 days after last dose of study drug. 24. The participant, participant's Parent(s) or Legal Guardian is an immediate family member, study site employee, or is in a dependent relationship with a study site employee who is involved in the conduct of this study or may consent and assent under duress. Students of the institution/research facility who are under the supervision of, or in a subordinate role to, the investigator are also ineligible. 25. The participant or participant's Parent(s) or Legal Guardian, in the opinion of the investigator, is unlikely to comply with the protocol requirements or is unsuitable for any other reason. 26. The participant has participated in another clinical study and/or has received any investigational compound within 30 days prior to Screening.