Pericarditis typically presents with classic symptoms of acute sharp, retrosternal, and pleuritic chest pain. It can have several different underlying causes including viral, bacterial, and autoimmune etiologies. The mainstays of pericarditis treatment are nonsteroidal anti-inflammatory drugs and colchicine with glucocorticoids or other immunosuppressive drugs used for refractory cases and relapse. Myocarditis is an inflammatory disease of the cardiac muscle that is caused by a variety of infectious and noninfectious conditions. It mainly affects young adults (median age 30–45 years), and men more than women. The clinical manifestations of myocarditis are highly variable, so a high level of suspicion in the early stage of disease is important to facilitate diagnosis. The treatment of myocarditis includes nonspecific treatment aimed at complications such as heart failure and arrhythmia, as well as specific treatment aimed at underlying causes. Pericarditis and myocarditis associated with vaccine have been extremely rare before coronavirus disease 2019 (COVID-19). There is a small increase of incidence after COVID-19 messenger ribonucleic acid vaccine, but the relative risk for pericarditis and myocarditis due to severe acute respiratory syndrome coronavirus 2 infection is much higher. Therefore, vaccination against COVID-19 is currently recommended for everyone aged 6 years and older.