What are the causes of sudden increase in pulse rate in teens?

Increased pulse rate: There are several reason for sudden increase in pulse rate in teens, most common causes are 1.Cardiac arrythmia, high fever, hyperthyroidism, anxiety and certain medication can also cause increased heart rate.

Food sensitivities: Sudden increases in pulse rate can be a sign that you are "sensitive, " and therefore "reactive, " to a food that you have just eaten. In fact, one of the ways to see if you are "allergic" to a particular food is to take your pulse shortly after eating the food to see if your pulse has (temporarily) increased more than 10 beats per second. A handy diagnostic tool for food allergies...

Substance abuse: You should also be careful not to miss substance abuse in teenagers. Psychostimulants in particular (ritalin (methylphenidate) and others) are known to do that.