Tachycardia is common in hot weather in two ways: 1. In hot weather, there are certain changes in the body’s neurological and humoral regulation that lead to increased cardiac excitability, which can easily lead to physiological tachycardia. This condition usually does not require deliberate treatment, and the heart rate will return to normal after the ambient temperature is normalized. 2. Pathological tachycardia is usually associated with myocardial ischemia and massive water loss in a hot environment. If a patient has tachycardia combined with thirst and dizziness, dehydration is more likely and rehydration therapy is recommended. If the tachycardia is combined with chest pain and tightness, the relative lack of blood supply to the myocardium due to vasodilation should be considered, and treatment to improve the blood supply to the myocardium is required. Because of the high risk of sudden death from heart disease, patients are advised to seek medical attention promptly when similar symptoms occur to avoid delaying the condition by self-treatment.