| Cardiovascular |
| Angina pectoris, arrhythmias, heart failure, hypertension, hypovolemia, myocardial infarction, syncope (multiple causes), valvular disease, vascular collapse (shock) |
| Dietary |
| Caffeine, monosodium glutamate (Chinese restaurant syndrome), vitamin-deficiency diseases |
| Drug-related |
| Akathisia (secondary to antipsychotic drugs), anticholinergic toxicity, digitalis toxicity, hallucinogens, hypotensive agents, stimulants (amphetamines, cocaine, related drugs), withdrawal syndromes (alcohol, sedative-hypnotics), bronchodilators (theophylline, sympathomimetics) |
| Hematologic |
| Anemias |
| Immunologic |
| Anaphylaxis, systemic lupus erythematosus |
| Metabolic |
| Hyperadrenalism (Cushing's disease), hyperkalemia, hyperthermia, hyperthyroidism, hypocalcemia, hypoglycemia, hyponatremia, hypothyroidism, menopause, porphyria (acute intermittent) |
| Neurologic |
| Encephalopathies (infectious, metabolic, toxic), essential tremor, intracranial mass lesions, postconcussive syndrome, seizure disorders (especially of the temporal lobe), vertigo |
| Respiratory |
| Asthma, chronic obstructive pulmonary disease, pneumonia, pneumothorax, pulmonary edema, pulmonary embolism |
| Secreting tumors |
| Carcinoid, insulinoma, pheochromocytoma |
