Overview
Infectious mononucleosis (glandular fever) is a viral illness caused by Epstein-Barr virus (EBV). It most commonly affects teenagers and young adults, presenting with severe fatigue, sore throat, fever, and swollen lymph nodes. Most people recover fully within 2 to 6 weeks, though fatigue can persist for months. Almost all adults have been infected with EBV by age 40.
How common is it?
Glandular fever mostly affects teenagers and young adults and is most common between ages 15 and 24. Symptoms can last for weeks, with tiredness sometimes lasting longer.
Causes and risk factors
EBV (Human Herpesvirus 4) is transmitted primarily through saliva. The virus infects B lymphocytes and causes a marked T-lymphocyte response responsible for most clinical features.
Common risk factors
- Close contact with saliva of an infected person (kissing disease)
- Sharing drinks, utensils, or food
- Teenagers and young adults most susceptible (primary EBV infection in childhood is usually mild)
- Immunosuppressed individuals: severe or prolonged illness
Symptoms
- Severe sore throat (often the most prominent symptom, with white exudate on tonsils)
- Profound fatigue
- High fever
- Grossly swollen lymph nodes, especially at the back of the neck
- An enlarged spleen can occur, increasing the risk of injury during contact sports.
- Liver swelling or inflammation can occur; yellow skin or eyes needs medical assessment.
- Morbilliform (measles-like) rash if ampicillin or amoxicillin given erroneously
When to see a doctor
Seek emergency help for severe breathing difficulty, inability to swallow saliva, or severe abdominal pain, especially with faintness. An enlarged spleen can rarely rupture. Seek urgent advice for dehydration or worsening jaundice.
Diagnosis
Diagnosis uses symptoms and examination, with blood tests when needed. EBV-specific antibodies can help confirm infection. Monospot tests can be falsely negative or positive and do not reliably confirm EBV on their own. Liver tests may also be checked.
Treatments
Supportive care
Rest during the acute illness, adequate fluid intake, and paracetamol or ibuprofen for fever and sore throat. No specific antiviral treatment is recommended for uncomplicated cases.
Corticosteroids
A short course of prednisolone is indicated for severe pharyngeal swelling causing airway compromise, severe thrombocytopenia, or neurological complications.
Avoidance of contact sports
Avoid contact sports, heavy lifting and strenuous exercise while recovering, usually for at least the first month. Discuss the timing of return with a clinician, especially if the spleen is enlarged or symptoms persist.
Self-care and lifestyle
- Rest while unwell and return to ordinary activity gradually as symptoms allow; avoid strenuous exercise until advised it is safe.
- Avoid alcohol (liver involvement is common)
- Tell your prescriber if glandular fever is suspected: amoxicillin or ampicillin can cause a rash and do not treat EBV. Do not start or stop a prescribed antibiotic without advice.
- Avoid contact sport until splenomegaly confirmed to have resolved
Prevention
EBV spreads through saliva. Avoid kissing and sharing drinks or utensils while unwell, and practise hand hygiene. There is no vaccine; transmission cannot always be prevented.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to diagnosis, self-care, treatment, urgent-care guidance, key facts, prevention, frequency, symptoms. This update covers the named sections; a full review of the remaining guide is pending.