What is glandular fever?
Glandular fever, known medically as infectious mononucleosis and often shortened to 'mono', is a common viral infection. It is usually caused by the Epstein-Barr virus (EBV), a very widespread virus that most people are infected with at some point in their lives. When infection with EBV happens in childhood it often causes few or no symptoms, but when it occurs in the teenage years or early adulthood it more commonly produces the recognisable illness of glandular fever.
The illness is characterised by a triad of a severe sore throat, marked tiredness, and swollen glands, usually alongside a fever. It is sometimes called the 'kissing disease' because it spreads through saliva, including through kissing but also through sharing cups, cutlery or toothbrushes and through coughs and sneezes. Although glandular fever can make you feel very unwell for a couple of weeks, it is rarely serious and almost everyone makes a full recovery.
Symptoms of glandular fever
Glandular fever symptoms often develop gradually over a week or two after infection and can be more intense and longer-lasting than a typical sore throat or cold. The most common symptoms include:
- •A severe sore throat, often worse than an ordinary sore throat, that can make swallowing painful
- •Extreme tiredness and fatigue, which is often the most striking feature
- •A high temperature (fever)
- •Swollen, tender glands in the neck, and sometimes the armpits and groin
- •Swollen tonsils, sometimes with a whitish coating
- •Headache and aching muscles
- •A general feeling of being unwell (malaise) and loss of appetite
- •Sometimes a swollen spleen, causing discomfort in the upper left abdomen
Glandular fever versus tonsillitis and strep throat
Because glandular fever causes a severe sore throat with swollen tonsils and glands, it can be mistaken for tonsillitis or strep throat, and in the early days they can genuinely look alike. The clue that points towards glandular fever is the combination of an unusually severe or prolonged sore throat with profound tiredness and widely swollen glands, particularly in a teenager or young adult, and symptoms that drag on rather than settling within a week.
The distinction matters for a practical reason. Glandular fever is viral, so antibiotics do not help it. In fact, a particular class of antibiotics (amoxicillin and ampicillin) can cause a widespread rash in someone with glandular fever, which is one reason doctors are careful about diagnosing a sore throat correctly before prescribing. If a sore throat is severe, lingers beyond a week, or comes with marked fatigue and swollen glands, a doctor can arrange a blood test to check whether glandular fever is the cause.
How is it diagnosed and treated?
A doctor may suspect glandular fever from the pattern of symptoms — especially the combination of severe sore throat, fatigue and swollen glands in a young person — and can confirm it with a blood test. Blood tests can detect antibodies the body makes in response to the Epstein-Barr virus, and may also show changes in the white blood cells typical of the infection. Not everyone needs a test, but it is helpful when the diagnosis is unclear or symptoms are severe.
There is no specific cure or antiviral treatment for glandular fever, because it is caused by a virus the body clears on its own. Treatment focuses on easing symptoms and resting while you recover. This means getting plenty of rest, drinking fluids to stay hydrated, and using paracetamol or ibuprofen to reduce fever and ease the sore throat and aches. Most people gradually feel better over two to four weeks, though the tiredness can take longer to lift completely.
Recovery and looking after yourself
Recovery from glandular fever is usually a matter of patience and rest rather than any particular treatment. The sore throat and fever tend to improve within a couple of weeks, but the fatigue is often the last symptom to go and can persist for several weeks or occasionally months. Trying to return to full activity too quickly can prolong the tiredness, so it helps to build back up gradually and listen to your body rather than pushing through exhaustion.
One important piece of advice concerns the spleen. Glandular fever can cause the spleen to swell, and a swollen spleen is more vulnerable to injury. For this reason, it is generally advised to avoid contact sports, heavy lifting and vigorous exercise for the first few weeks of the illness — usually at least three to four weeks, and longer if advised — to reduce the small risk of the spleen rupturing. Your doctor can advise on when it is safe to return to sport based on your recovery.
Because glandular fever spreads through saliva, simple measures reduce the chance of passing it on while you are unwell: avoid kissing, do not share cups, cutlery, toothbrushes or food, and cover coughs and sneezes. The period of contagiousness is not precisely defined and the virus can be present in saliva for some time, but common-sense hygiene during the illness is the sensible approach.
When glandular fever needs more attention
For the great majority of people, glandular fever is an unpleasant but self-limiting illness that resolves with rest. However, a few situations warrant prompt medical attention. Severe abdominal pain, particularly in the upper left side, could indicate a problem with the swollen spleen and should be assessed urgently. Difficulty breathing or swallowing, or a throat so swollen that it is hard to drink, also needs medical review, as very occasionally the swelling around the throat becomes significant.
Other reasons to seek advice include symptoms that are unusually severe or that are getting worse rather than better, signs of dehydration from being unable to drink, or a persistent high fever. While complications of glandular fever are uncommon, being aware of these warning signs means you can seek help in the rare situations that need it, while managing the typical illness confidently at home. If you are unsure whether your symptoms are normal for glandular fever, it is always reasonable to check with a doctor.