What causes palpitations and a racing heart?

The causes of palpitations are diverse, mainly including the following: 1. **Heart diseases**: Such as arrhythmias (ventricular premature beats, atrial premature beats, tachycardia or bradycardia), myocardial ischemia, myocarditis, heart failure, and others. These conditions directly affect the heart's function and rhythm, leading to symptoms of palpitations. 2. **Endocrine system diseases**: For example, hyperthyroidism. Excessive secretion of thyroid hormones causes an increased heart rate, thereby triggering palpitations. 3. **Physiological and emotional factors**: Stress, anxiety, vigorous exercise, consumption of stimulants such as strong tea or coffee, and excessive fatigue can all cause sympathetic nervous system activation, leading to increased heart rate and palpitations. 4. **Anemia and hypoglycemia**: In cases of anemia, the heart rate increases to meet the body's demand for blood supply and oxygen due to low hemoglobin levels. Hypoglycemia can also lead to palpitations, often accompanied by symptoms such as sweating and hand tremors. 5. **Medication factors**: Certain medications, such as those containing hormones or some antihypertensive drugs, may secondarily cause palpitations. 6. **Diseases of other systems**: Such as respiratory diseases (COPD, bronchial asthma, etc.) and electrolyte disturbances, which may also lead to palpitations. When related symptoms occur, timely medical attention should be sought to identify the underlying cause through appropriate examinations, and targeted treatment should be carried out under the guidance of a physician.