Glandular fever, also called infectious mononucleosis, is usually caused by Epstein–Barr virus. It spreads mainly through saliva. Teenagers and young adults are more likely to develop typical symptoms, but infection can occur at any age.
Symptoms
- Severe sore throat and swollen tonsils
- Swollen glands, especially in the neck
- Fever and marked tiredness
- Headache, body aches or a rash
- Occasionally an enlarged spleen or liver inflammation
Fatigue may continue for several weeks or longer after the throat and fever improve.
Diagnosis and treatment
A clinician may diagnose the illness from symptoms and examination and may order blood tests. Antibiotics do not treat the virus. Rest, fluids and suitable pain or fever medicine can help. Amoxicillin or ampicillin can cause a widespread rash in people with glandular fever and should not be taken unless specifically advised after assessment.
Protecting the spleen
An enlarged spleen can rupture after an impact. Avoid contact sports, heavy lifting and activities with a risk of abdominal injury until a clinician says it is safe to resume them.
When to seek urgent help
Seek urgent care for difficulty breathing or swallowing, inability to drink, severe dehydration, jaundice or worsening illness. Sudden severe pain in the upper left abdomen, pain spreading to the left shoulder, dizziness or collapse may indicate a ruptured spleen and requires emergency help.
Sources
Reviewed: 28 August 2026