Is mononucleosis serious?

Mark P. Caruso, MD
Internal Medicine
Mononucleosis is often referred to as "mono." It is a very common viral illness. When mono strikes young children, it is usually mild and can pass as a common cold or the flu. 
But when mono hits during adolescence or adulthood, the disease can be much more serious.
It begins with flu-like symptoms -- fever, headache, and general malaise. After a few days, the lymph glands begin to swell, although this symptom is not noticeable in everyone. Swollen glands of the neck are especially typical of mono.
Most people develop a sore throat, which can be very severe, with inflamed tonsils. A fever -- usually no higher than 104 degrees -- can develop and may last up to three weeks.
The fatigue factor sets mono apart from even a bad case of the flu. Most people who come down with mono feel much better within two or three weeks, although fatigue may last for two months or even longer.

Mononucleosis itself is not usually serious, but the complications can be. Mononucleosis causes sore throat, fever, and fatigue, and in 50% of cases, it causes the spleen to enlarge. An enlarged spleen may rupture, which can be life threatening. Some may also experience liver inflammation. Rare but serious complications include an enlarged heart, brain inflammation, anemia, obstructed airways due to swollen tonsils, clotting problems, and nervous system complications.

Continue Learning about Viral Infections

Viral Infections

Viral Infections

Viral infections like herpes simplex, respiratory syncytial virus (RSV), chicken pox and rotavirus are infections caused by a virus instead of a bacterium. Viral infections do not respond to antibiotics, but some specific viruses ...

like influenza A and B can be treated with certain antiviral medications. Most commonly, treatment for viral infections includes drinking lots of fluids, getting rest, eating well and letting the illness run its course.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.