Glandular Fever (Mono): Symptoms, Recovery and When to Worry

Glandular fever, also called infectious mononucleosis or “mono”, is a viral infection usually caused by the Epstein-Barr virus (EBV). It spreads through saliva, which is why it is nicknamed the kissing disease, and it is most common between the ages of 15 and 24.¹ When it starts with a severe sore throat, fever, large tonsils and swollen neck glands, it is easily mistaken for tonsillitis.

This guide covers the symptoms, how it spreads, how it is diagnosed, what recovery looks like, and when you should get help without waiting.

What is glandular fever?

Glandular fever is an infection usually caused by the Epstein-Barr virus, and it mostly affects teenagers and young adults.¹ In young children the infection is often mild or causes no symptoms at all; older children and adults typically have fever, widespread swollen lymph nodes and a sore throat with a white-grey coating on the tonsils.²

The virus spreads through saliva, most often by kissing or by sharing cups and cutlery.¹ The incubation period is about 4 to 6 weeks.² The NHS notes that you can pass it on for up to 7 weeks before symptoms appear and for several months after you feel better.¹ Most people only have it once; a second episode is rare.³

Symptoms

• a high temperature;
• a sore throat and pain on swallowing;
• swollen glands in the neck, armpits or groin;
• headache and marked tiredness;
• sometimes a rash.¹

Symptoms usually last from one to several weeks.² For most people tiredness settles within a few weeks, but around 1 in 10 develop post-viral fatigue that can last several months.³

How it differs from tonsillitis

Because the tonsils can become large and coated, glandular fever often looks like bacterial tonsillitis at first. The pointers below help, but an examination and sometimes a blood test are needed to tell them apart.^1,4

“I took antibiotics, my throat did not get better and then I came out in a rash” is a classic story that should raise the possibility of glandular fever.² How the decision about tonsil surgery is made for repeated tonsillitis is explained in when is tonsillectomy needed.

How it is diagnosed

Diagnosis is based on the examination and a blood test. The test looks for antibodies to the Epstein-Barr virus and helps rule out conditions such as tonsillitis.¹ Very early in the illness the test can be negative; if glandular fever is still suspected, it may be repeated a few weeks later.³

Treatment and self-care

Glandular fever is viral, so antibiotics are not used, and it gets better on its own.¹ While you recover:^1,3

• rest;
• drink plenty of fluids (small, frequent sips if swallowing hurts);
• use painkillers such as paracetamol or ibuprofen; do not give aspirin to children under 16;
• avoid alcohol until you are better;
• avoid kissing, sharing cups or cutlery, and giving blood.

There is not enough evidence to recommend steroids routinely.³ If the tonsils become so large that swallowing or breathing is seriously affected, this needs urgent assessment, and treatment is decided by the doctor.

Sport, the spleen and getting back to normal

The spleen can enlarge during the infection and becomes vulnerable to knocks, so contact sports should be avoided during recovery.² Patient.info advises avoiding contact sports such as rugby for eight weeks; the spleen settles in about three weeks in most people but can take eight weeks in some.³ Heavy lifting and strenuous exercise should also be avoided for a while.¹

You can go back to work or school once you feel better,¹ and children do not need to be excluded from school.² Athletes, especially in contact sports, should plan their return with their doctor.

When it is urgent

The NHS advises calling emergency services straight away if:¹

• you cannot swallow, including your own saliva;
• you are having severe difficulty breathing;
• you have severe tummy pain (which can be related to the spleen).

Difficulty or pain when swallowing, breathlessness, a very high temperature, a severe or worsening sore throat, swelling on either side of the neck or extreme exhaustion also need same-day advice.¹ Do not drive yourself to hospital in these situations.

Frequently asked questions