Enlarged tonsils. One of the distinctive symptoms of mononucleosis is a considerable swelling of the tonsils. This swelling can become so extensive that you may have trouble breathing, and certainly have extreme issues in ingesting food or drink. The enlarged tonsils may also be a source of considerable pain, and medical care is definitely advised at the earliest.

A rapid pulse. You may be intrigued to know that when you suffer from mononucleosis your heart rate is accelerated, much the same as it is when you exercise. The accelerated heart rate is a response to stress – in the case of exercise, it is physical stress, while in the case of mononucleosis it is the stress of the infection. A rapid heart rate at rest is a symptom that demands closer examining. In mononucleosis, your heart should put out ten extra beats every minute when at rest.