Mononucleosis (also called mono) is a contagious viral infection. Most infants and children exposed to the virus get only mild flu-like symptoms or no symptoms at all. However, infection is usually more serious in teens and young adults. While the virus is active, it causes symptoms and can spread to others. After symptoms subside, the virus stays in the body and eventually becomes inactive. The virus can reactivate and develop symptoms, especially in people with weak immune systems.

The virus is usually spread by contact with saliva, often by kissing, or sharing food or eating utensils. It may also spread by breastmilk, blood, or sexual contact. It takes about 4 to 6 weeks to develop symptoms after exposure.

Early symptoms include headache, nausea, tiredness and general muscle aching. This is followed by sore throat and fever. Lymph glands in the neck, under the arms, or in the groin may be swollen. Symptoms usually go away in about 1 to 2 months. But they can last up to 4 months.

In the first few days to weeks, a common blood test (the monospot test) us ed to diagnose this disease may be negative even though you have the illness. In this case, other tests may be done.

Taking the antibiotics ampicillin or amoxicillin during a mono infection may cause a skin rash. This is not serious and will fade in about a week. The rash may not mean you are having an allergic reaction to the antibiotic.

Mono can cause your spleen to swell. The spleen is a fist-sized organ in the upper left abdomen that stores red blood cells. Injury to a swollen spleen can cause the spleen to rupture. This can cause life-threatening internal bleeding. To prevent this from happening, don't play contact sports or do strenuous activity for 8 weeks, or until your healthcare provider says it's OK. A sharp blow or pressure to the area could rupture a swollen spleen

Home care

  • Rest in bed until the fever and weakness have gone away.

  • Drink plenty of fluids, but don't drink alcohol. Otherwise, you may eat a regular diet.

  • Ask your healthcare provider about using over-the-counter medicines to treat symptoms such as fever, pain, or an itchy rash.

  • Over-the-counter throat lozenges may help soothe a sore throat. Gargling with warm salt water (1/2 teaspoon in 1 glass of warm water) may also be soothing to the throat.

  • You may return to work or school after the fever goes away and you are feeling better. Continue to follow any activity restrictions you have been given.

Preventing spread of the virus

To limit the spread of the virus, don't expose others to your saliva for at least 6 months after your illness (no kissing or sharing utensils, drinking glasses, or toothbrushes).

Follow-up care

Follow up with your healthcare provider within 1 to 2 weeks, or as advised to be sure that there are no complications. If symptoms of extreme fatigue and swollen glands last longer than 6 months, see your healthcare provider for further testing.

When to seek medical advice

Call your healthcare provider right away if any of the following occur:

  • Excessive coughing

  • Yellow skin or eyes

  • Trouble swallowing

  • Dizziness

  • Paleness

Call 911

Call 911 if any of the following occur:

  • Severe or worsening abdominal pain

  • Trouble breathing

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