Myocarditis is the inflammation of the heart muscle. It is a rare disease and can be caused by several factors: infections, allergic reactions, diseases with an immunological cause, etc. In some patients there are no symptoms, but in the majority of cases this disease manifests through chest pain, fatigue, fever, joint pain, or respiratory distress, among other symptoms. A series of tests (a general analysis, a heart ultrasound and an electrocardiogram) are required for diagnosis. Treatment aims to eradicate the cause of the inflammation of the heart muscle through the prescription of antibiotics or anti-inflammatories, and the recommendation of a low-salt diet, or a decrease in physical activity. In many cases, recovery with appropriate treatment can lead to the patient’s complete cure, avoiding major complications such as heart failure.