Medical information for patients

Glandular fever (Infectious mononucleosis)

Glandular fever (Infectious mononucleosis) is a virus infection causing sore throat, fever, enlarged and tender glands, and sometimes inflammation of the liver (hepatitis). It frequently causes a prolonged period of tiredness and debility.


Glandular fever often starts with a few days of mild symptoms, including headache, and tiredness. The major symptoms then develop, and may last seven to twenty one days. They vary in how badly they affect you, but usually include a fever, sore throat, and tiredness, along with aches and pains all over the body.

This phase of the illness may last a few days to a few weeks. It is accompanied by tender enlargement of the glands (the lymph glands or lymph nodes) which are around the body to help defend against infection.

A small number of people (about one in ten) develop a faint red rash on the trunk and limbs. Sometimes the liver may become inflamed (hepatitis), even to the extent of making you go yellow (jaundiced).

After the worst of the initial symptoms have passed, most people continue to feel tired all the time, and easily exhausted. This is frequently accompanied by depression.

After a period of weeks or months, most people return to normal.


The spleen, an organ tucked in under the ribs on the left side at the back, is sometimes enlarged in glandular fever. A rare complication is for the spleen to get very swollen and to rupture.

If this happens an urgent operation to remove the spleen is required, as it can lead to heavy internal bleeding. This would probably be associated with abdominal pain and a sudden deterioration in the patient. This is a rare occurrence, but if you suspect such a change in yourself or someone in your family, it is wise to contact the duty doctor.


The cause of glandular fever (infectious mononucleosis) is a virus known as Epstein-Barr virus (EBV). This is most frequently seen in teenagers and young adults. It is thought to spread in a similar way to many other viruses, from saliva, and is sometimes jokingly referred to as the kissing disease, as it is often passed from boyfriend to girlfriend or vice versa.

Incubation period

Glandular fever takes about four to seven weeks to come out after contact with someone who has it, although it is sometimes faster.


It appears that someone who catches glandular fever may be infectious for weeks to months afterwards, but just over half of the population have developed immunity while young, with a milder form of the condition. These people are not at risk of catching it again. The rest are more likely to pick up glandular fever as teenagers or young adults.


Your doctor may suspect the diagnosis from the fact that you have recently been in contact with someone with glandular fever. It may be suspected from your symptoms and the findings on examining you.

Your doctor may ask for a blood test to look for any abnormalities in the white blood cells, and a specific test for glandular fever. If your doctor suspects hepatitis a test will be done to check on the liver.


There is no specific treatment for glandular fever. Antibiotics are not helpful, as this is a virus infection. In fact there is one antibiotic, ampicillin, which is more likely to cause a rash if given to people with glandular fever.

You can treat the symptoms of fever and pain with pain killers (analgesics) such as paracetamol or non-steroidal anti inflammatory drugs such as ibuprofen or aspirin (16+ only). You will probably need more rest and sleep than usual for a prolonged period.

Drink plenty of fluids, even if you are off your food.

If you have any evidence of hepatitis you should avoid alcohol until the liver is completely recovered, which might be many months. Your doctor will, of course, advise you.

It is wise not to rush back to full activity too soon, and to build up slowly.

Glandular fever often affects children and young adults at the time of critical examinations, and may well affect revision and even performance in the examinations. If this applies to you, you would be well advised to either consider delaying the examination, or asking your doctor for a letter to present to the examining board before you sit the exam.

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