Mono Symptoms

Infectious Mononucleosis Basics

Fatigue is a common mono symptom.
Fatigue is a common mono symptom. Photo (c) Ana Blazic

Infectious mononucleosis, or mono, can often be hard to recognize or diagnose.

After all, the main symptoms of mono are very similar to the symptoms of strep throat and many viral infections.

Mono Symptoms

Surprisingly, some children, especially those who are younger than five years, may not have any symptoms at all when they get mono.

Most other children, especially older children and teens, do get classic mono symptoms, which can include:

  • a sore throat*, which is often described as the worst sore throat the child has ever had
  • a high fever*
  • enlarged lymph nodes or glands in the neck*, armpit, or groin
  • malaise and fatigue* (not feeling well and feeling tired)
  • anorexia (loss of appetite)
  • muscle aches
  • a rash, especially if your child was taking antibiotics, like ampicillin or amoxicillin
  • a headache
  • nausea
  • abdominal pain

(*classic symptoms of mono)

If your child has mono, your pediatrician might also notice that your child has an enlarged spleen, an enlarged liver, arthralgia (joint pain without swelling or other signs of arthritis), jaundice, many enlarged lymphocytes (atypical lymphocytosis) on a blood test, elevated liver function tests, and a positive mono spot test.

Long-Term Mono Symptoms

When parents think of mononucleosis, they usually picture symptoms lasting many months and a child who is going to miss a lot of school. Fortunately, most kids get over their main mono symptoms, especially the fever and sore throat, over 2 to 4 weeks.

The malaise and fatigue can sometimes take several more months, or more rarely, years, to completely go away, so it may take some time for your child to get back to full activities.


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