Heartburn in an 8-year-old child can be caused by myocarditis, gastroesophageal reflux, and intercostal muscular neuritis. 1. Myocarditis: usually occurs a few days after an upper respiratory tract infection, and the pain in the mouth of the heart can radiate to the abdomen, while the child is accompanied by pallor, poor spirit, poor appetite and other systemic symptoms. 2. Gastroesophageal reflux (GERD): the typical symptom is also pain in the heart and mouth, due to the reflux of gastric acid to the throat, triggering a burning sensation in the throat, manifested as pain in the heart and mouth, accompanied by acid reflux, belching and other conditions. 3. Intercostal neuritis: usually caused by viral infection, thoracic spine tuberculosis, thoracic spine injury, can be manifested as pain in the mouth of the heart, usually distributed along the intercostal nerve. The 8-year-old child’s heart pain must be taken seriously, and it is recommended to immediately consult a doctor to identify the cause and actively treat it.