The heart rate will increase when there is a fever, and this can be seen in physiologic conditions, such as strenuous exercise, emotional excitement, and the consumption of stimulating foods such as strong tea and coffee. In addition, for the pathological state, can be seen in infectious diseases caused by fever state, can appear heart rate accelerated. Endocrine diseases such as hyperthyroidism can cause rapid heart rate, and blood system diseases including severe anemia can cause rapid heart rate. Various organic heart diseases can cause rapid heart rate, and diseases other than circulatory system diseases can also cause rapid heart rate. For drug factors, it can also cause rapid heart rate. There are many factors that can cause an increased heart rate, with fever being one of the common causes of increased heart rate.