Early symptoms of myocarditis in children include weakness, palpitations (rapid heartbeat, often accompanied by panic), symptoms of infection, etc. In mild cases, there are no obvious clinical manifestations, and symptoms of heart failure may appear in later stages. 1. Weakness, palpitation: some patients have insidious onset of symptoms, such as weakness, activity limitation, palpitation, chest pain and so on. 2. Symptoms of infection: typical cases have respiratory or intestinal infections a few days or 2 weeks before the appearance of cardiac symptoms, and may have fever, sore throat, diarrhea, skin rash and other symptoms. 3. Heart failure symptoms: mainly lack of appetite, nausea, vomiting, dyspnea, pallor, fever, precordial discomfort, dizziness, abdominal pain, myalgia and so on. When children have the above symptoms, parents should take them to the hospital in time and standardize the treatment under the guidance of doctors.