You must be at least 17 years old to donate to the general blood supply, or 16 years old with parental/guardian consent, if allowed by state law. Learn more about the reasons for a lower age limit.
Other Causes of Elevated Heart Rate. Elevated heart rate when sick is actually your heartâs aid in order to quell the sickness. However, there can be other causes for elevated heart rate as well. Electrical signals produced and sent to the heart tissues are responsible for controlling the heart rate.
A fever can increase the body's heart rate, especially if the fever is high. Fevers can also cause sweating, shivering or chills, which can make the body feel too cold, causing the heart beat faster as it tries warm up the body.