Mononucleosis (Mono)

How mono spreads

Epstein-Barr virus spreads mainly through saliva: kissing, sharing cups, bottles, utensils, toothbrushes or lip balm, and sometimes through coughs. It can also spread through blood and sexual contact.

• Symptoms appear 4 to 6 weeks after exposure, so people often do not know where they caught it.
• People can shed the virus in saliva for months after symptoms go away, and intermittently for life.
• Most adults have had EBV at some point. In young children, infection is often mild or symptom-free.

Symptoms

• extreme tiredness and weakness, often the first and longest-lasting symptom
• sore throat, often severe, with swollen tonsils that may have a white coating
• fever
• swollen lymph nodes, especially at the back and sides of the neck, and sometimes in the armpits and groin
• headache and body aches
• loss of appetite
• swollen spleen, felt as fullness or discomfort in the upper left belly
• swollen liver or mild jaundice
• puffy eyelids
• a rash, especially after taking amoxicillin or ampicillin

Mono vs strep throat

The two can occur together, and a strep test is often done as well.

Diagnosis

• Examination: throat, lymph nodes, spleen and liver.
• Monospot (heterophile antibody) test: a quick blood test. It can be falsely negative in the first week and in children under 4.
• EBV-specific antibody tests: more accurate, and show whether the infection is recent.
• Blood count: often shows increased lymphocytes, including atypical lymphocytes.
• Liver tests: often mildly raised.
• Strep test to check for coexisting strep throat.

Treatment and home care

There is no specific antiviral treatment, and antibiotics do not help. Care focuses on symptoms:

• rest as needed, then a gradual return to activity
• fluids to prevent dehydration
• pain and fever relief: acetaminophen (paracetamol) or ibuprofen at the label dose. Do not give aspirin to children or teenagers.
• throat comfort: salt-water gargles, lozenges, cold drinks and soft foods
• steroids are sometimes given for severe tonsil swelling that threatens breathing
• avoid alcohol while the liver is inflamed

Amoxicillin and ampicillin often cause a widespread rash in people with mono. This is not usually a true allergy, but tell your doctor.

Spleen precautions and return to sport

The spleen swells in about half of people with mono and is at risk of rupture, which is rare but serious. Most ruptures occur in the first 3 weeks.

• Avoid contact sports, heavy lifting and vigorous activity for at least 3 to 4 weeks from the start of symptoms, and longer if the spleen is still enlarged or you still feel unwell.
• Your doctor will advise when it is safe to return, sometimes with an ultrasound.
• Sudden upper left belly pain is an emergency.

Complications

• ruptured spleen (rare)
• airway obstruction from very swollen tonsils
• hepatitis and jaundice
• low blood counts (anemia, low platelets)
• rarely, nerve problems such as Guillain-Barre syndrome, meningitis or encephalitis
• prolonged fatigue, and in some people a post-infectious fatigue syndrome resembling chronic fatigue syndrome

EBV is also linked over the long term to some lymphomas and nasopharyngeal cancer, and to multiple sclerosis, though most people with EBV never develop these.

How long mono lasts

• Fever and sore throat: usually improve within 1 to 2 weeks.
• Swollen glands and spleen: settle over 3 to 4 weeks.
• Fatigue: often lasts 2 to 4 weeks, but can persist for several months in some people.

Preventing spread

• do not kiss or share drinks, utensils, toothbrushes or lip products while sick
• wash hands regularly
• there is no vaccine for EBV

Students usually can return to school when they feel well enough, as isolation is not required.

Frequently asked questions

How long is mono contagious?

People can spread EBV in saliva for weeks to months after symptoms start, and occasionally for life. Avoid kissing and sharing drinks or utensils while ill and for several weeks afterward. Many people who spread it have no symptoms.

How long does mono last?

Most symptoms improve within 2 to 4 weeks. Fatigue can last longer, sometimes several months. Gradually increasing activity as energy returns helps recovery.

Can you get mono twice?

Usually not. After infection, EBV stays dormant in the body and you develop lifelong immunity. The virus can reactivate without symptoms. A second mono-like illness may be caused by a different virus such as cytomegalovirus.

When can I play sports after mono?

Avoid contact sports and heavy lifting for at least 3 to 4 weeks after symptoms start, and until your doctor confirms your spleen is no longer enlarged and you feel well. Returning too early risks a ruptured spleen.

Is mono serious?

Usually not. Most people recover fully with rest. Rare complications include a ruptured spleen, severe tonsil swelling that blocks breathing, hepatitis and nerve problems. Seek urgent care for sudden belly pain, trouble breathing or inability to drink.