In mononucleosis, the headache is usually mild but persistent. When the patient has fever, it may become moderate-severe and it may be necessary to take over-the-counter painkillers to relieve it.
Fatigue is an important symptom of mononucleosis from the start of the infection. Many experts say that fatigue in mononucleosis is caused by all the systemic disorders (including alterations in the blood cells) that the virus may cause. Patients describe it as lack of energy or motivation to do something.
This symptom is usually acute, but in some patients, it becomes chronic and lasts between 3 and 6 months.