Reviewed by The Wellness Team. Last reviewed October 2026.
A sore throat that will not shift, crushing tiredness and swollen glands that drag on for weeks often turn out to be glandular fever. It is common in teenagers and young adults, but it can strike at any age. Here is how to recognise it, how a simple blood test confirms it and what recovery really looks like.
What is glandular fever
Glandular fever, also called infectious mononucleosis, is usually caused by the Epstein-Barr virus. It spreads through saliva, which is why it is sometimes called the kissing disease, though sharing drinks and cutlery spreads it too. Most people catch the virus at some point in life; only some develop the full illness.
Symptoms of glandular fever
- A severe sore throat that can look like tonsillitis
- Swollen, tender glands, especially in the neck
- Profound tiredness that feels out of proportion to everything else
- Fever, sweats and aching muscles
- Loss of appetite, and sometimes a tender upper left abdomen from an enlarged spleen
- Occasionally a widespread rash, particularly if amoxicillin or ampicillin has been taken
Symptoms typically build over one to two weeks. In younger children the illness is often mild or passes unnoticed.
How glandular fever is diagnosed
A blood test confirms it. A full blood count shows a characteristic pattern of white cells, and a specific antibody test (sometimes called the Monospot or heterophile antibody test) confirms recent Epstein-Barr infection. Blood tests also check liver function, which is commonly affected, and help rule out other causes of a prolonged sore throat and fatigue.
How long glandular fever really lasts
The acute illness usually settles over two to four weeks. The tiredness is the part that lingers: most people feel fully back to normal within two to three months, but a minority find fatigue persists for longer. Recovery is not linear, and doing too much too soon commonly sets people back a few days.
Treatment and what actually helps
There is no specific antiviral treatment and antibiotics do not help, because glandular fever is viral. NICE guidance supports:
- Rest in the acute phase, then a gradual return to normal activity paced by symptoms
- Plenty of fluids and regular meals as appetite returns
- Paracetamol or ibuprofen for fever and throat pain
- Avoiding alcohol while the liver is affected
- Avoiding contact sports and heavy lifting for at least four weeks, because an enlarged spleen is vulnerable to rupture
When to see a GP
Book a review if a severe sore throat and swollen glands last more than a week, if tiredness is stopping you working or studying, or if you are simply unsure what is wrong. Seek urgent help for severe abdominal pain (especially left sided), difficulty breathing or swallowing, jaundice, or confusion.
What an online GP can do today
A GP can assess your symptoms, arrange the confirming blood tests, check for other causes of prolonged fatigue, and advise on a safe, staged return to work, study or sport. A fit note can be issued for time off while you recover. Appointments cost £59 by phone, £150 by video and £220 in person at 10 Portman Square, Marylebone, and comprehensive blood panels are available from £495.
Same day appointments are usually available. Message us on WhatsApp at https://wa.me/447961280835 to book.
Sources: NICE Clinical Knowledge Summaries, Glandular fever (infectious mononucleosis); BMJ Best Practice, Infectious mononucleosis.
Reviewed by The Wellness Team