Bacteria can also result in myocarditis, although it is rare in patients with normal heart function and without a preexisting immunodeficiency. A list of the most relevant infectious organisms is below. Viral: adenovirus, parvovirus B19, coxsackie virus, rubella virus, polio virus, Epstein-Barr virus, hepatitis C virus, and severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2, causing COVID-19)
Protozoan: Trypanosoma cruzi and Toxoplasma gondii (causing Chagas disease and toxoplasmosis, respectively)
Bacterial: Brucella, Corynebacterium diphtheriae, Neisseria gonorrhoeae, Haemophilus influenzae, Actinomyces, Tropheryma whipplei, Vibrio cholerae, Borrelia burgdorferi, Leptospira, Rickettsia, Mycoplasma pneumoniae
Fungal: Aspergillus
Parasitic: Ascaris, Echinococcus granulosus, Paragonimus westermani, Schistosoma, Taenia solium, Trichinella spiralis, visceral larva migrans, Wuchereria bancrofti

Immune conditions
Allergic reaction (e.g., to acetazolamide or amitriptyline)
Kawasaki disease
Autoimmunity (scleroderma, lupus, sarcoidosis, and systemic vasculitides)
Toxic shock syndrome

Drug reactions and toxins
Anthracyclines and other forms of chemotherapy
Antipsychotics including clozapine
Alcohol
Stimulants such as mephedrone and cocaine
Arsenic
Carbon monoxide
Snake venom
Heavy metals (copper or iron)

Vaccination
Myocarditis and pericarditis can be a rare side effect of some vaccines like the smallpox vaccine. Some COVID-19 vaccination doses carry a very small risk (33 per million overall) of causing myocarditis and pericarditis, more so in young men at repeated administration. According to a meta-analysis that does not differentiate between the two mRNA-vaccines BNT162b2 and mRNA-1273, the risk is less than that associated with COVID-19 itself. In adolescent males aged 16 to 17 years the crude reporting rate of myocarditis was 105.9 per million doses of the BNT162b2 vaccine.
Milrinone, sold under the brand name Primacor, is a pulmonary vasodilator used in patients who have heart failure. It is a phosphodiesterase 3 inhibitor that works to increase the hearts contractility and decrease pulmonary vascular resistance. Milrinone also works to vasodilate which helps alleviate increased pressures (afterload) on the heart, thus improving its pumping action. While it has been used in people with heart failure for many years, studies suggest that milrinone may exhibit some negative side effects that have caused some debate about its use clinically.Overall, milrinone supports ventricular functioning of the heart by decreasing the degradation of cyclic adenosine monophosphate (cAMP) and thus increasing phosphorylation levels of many components in the heart that contribute to contractility and heart rate. Milrinone is used as a drug that causes positive inotropy and it will lead to an increased force of contraction. Milrinone use following cardiac surgery has been under some debate because of the potential increase risk of postoperative atrial arrhythmias. However,  in the short term milrinone has been deemed beneficial to those experiencing heart failure and an effective therapy to maintain heart function following cardiac surgeries. There is no evidence of any long term beneficial effects on survival. In critically ill patients with evidence of cardiac dysfunction there is limited good quality evidence to recommend its use.Milrinone is administered IV only and eliminated unchanged in the urine. Dose adjustment is required for patients with renal impairment.