Mononucleosis (glandular fever): symptoms, causes, treatment and how long it lasts

The NHS says glandular fever is most common in people aged 15 to 24. NHS inform lists the common symptoms below and a longer set of other symptoms: feeling generally unwell, aching muscles, chills, sweating a lot, loss of appetite, pain around or behind the eyes, swollen tonsils and adenoids which may affect breathing, a very red throat that oozes fluid, small red or purple spots on the roof of the mouth, a rash, puffiness around the eyes, a tender or swollen tummy and jaundice.

• A high temperature (fever).

• A very sore throat.

• Swollen glands in the neck, and sometimes the head, armpits, elbows or groin.

• Extreme tiredness (fatigue).

• Headache.

• A rash, which may be harder to see on black or brown skin.

Mononucleosis is the American name for glandular fever. NHS inform says it is a type of viral infection that mostly affects young adults, normally gets better without treatment, but can make you feel very ill.

The cause is the Epstein-Barr virus. NHS inform says EBV may still be found in the saliva of someone who has had glandular fever several months after their symptoms pass, and that some people may continue to have the virus in their saliva on and off for years.

The NHS says glandular fever should get better by itself, and that you should start to feel better within 2 to 4 weeks. NHS inform says it normally lasts 2 to 3 weeks, but in some cases you can feel ill for months.

The NHS lists long-term tiredness (chronic fatigue), which may last for several months, among possible complications. You can go back to work or school as soon as you start to feel better, according to the NHS. It advises avoiding strenuous activities such as heavy lifting or playing sports.

There is no specific treatment. The NHS advises resting, drinking plenty of fluids to avoid dehydration (small sips frequently if swallowing is painful) and taking painkillers like paracetamol or ibuprofen. It says not to give aspirin to children under 16.

A GP may order a blood test to confirm glandular fever and to rule out other illnesses such as tonsillitis, testing for the Epstein-Barr virus. The NHS says the GP will not give you antibiotics because glandular fever is caused by a virus, so antibiotics will not work. NHS inform says that occasionally antibiotics or corticosteroids may be prescribed if complications develop, and that some people with severe symptoms may need to be looked after in hospital for a few days.

The NHS says glandular fever is spread through spit, so you can get it through kissing or by sharing cups or cutlery. NHS inform adds exposure to coughs and sneezes, sharing glasses and unwashed cutlery, and sharing toothbrushes.

The NHS says you are infectious for up to 7 weeks before you get symptoms, and you may be infectious for several months after being unwell. To prevent spreading it, wash your hands regularly, wash anything that may have your spit on it, and do not kiss others, share cups or cutlery, or give blood.

The NHS says to see a GP if you have a very high temperature or feel hot, cold or shivery, a severe sore throat, swelling on either side of your neck, extreme tiredness or exhaustion, or a sore throat that is not getting better.

Call NHS 111 if you have difficulty breathing (you may be more short of breath than usual) or difficulty and pain when swallowing. Call 999 if you cannot swallow, including your own spit, have severe difficulty breathing (gasping, choking or not able to get words out) or have severe stomach pain. NHS inform also lists a rasping breath (stridor) as a reason to phone 999.

The NHS says most people get better with no problems, but glandular fever can sometimes lead to other problems. NHS inform describes complications as uncommon but possibly serious.

• Liver conditions such as hepatitis.

• Heart problems such as inflammation of the heart.

• Kidney problems.

• Blood conditions, including low platelets (thrombocytopenia) or sepsis.

• Neurological conditions such as Guillain-Barre syndrome or Bell's palsy.

• A ruptured spleen, which may need surgery. This is why the NHS advises avoiding heavy lifting and sport while unwell.

• Long-term tiredness that may last for several months.

On the NHS, glandular fever is usually assessed by a GP or by NHS 111 if you are unsure, with a blood test to confirm it where needed. Most people are managed at home with self-care.

Private GP and walk-in clinics can also arrange blood tests. Severe breathing or swallowing difficulty needs emergency care, not an appointment.