Glandular fever (mononucleosis):
weeks of exhaustion & what helps

1. What is glandular fever?

Glandular fever — known medically as infectious mononucleosis — is an infection with the Epstein-Barr virus (EBV), a member of the herpesvirus family. The typical triad is fever, an inflamed throat and swollen lymph nodes. On top of that comes an exhaustion that many people find harder to deal with than all the other symptoms put together.^¹

The virus is extremely widespread: over 90 per cent of people carry EBV, and almost everyone has been infected by the age of 30.^² Most notice little or nothing of it. Like all herpesviruses, EBV stays in the body for life after the first infection — in a dormant state that, as a rule, causes no symptoms.

Important for putting things into perspective: after glandular fever, tiredness lasting a few weeks is normal. It becomes a concern if it has not improved after months or if it clearly gets worse every time you exert yourself — more on this in section 8 and in the article on fatigue.

2. Forms: from silent infection to mononucleosis

How an EBV infection shows itself depends heavily on age. In young children it often goes unnoticed, whereas in teenagers and young adults it frequently takes the form of full-blown mononucleosis.^¹,²

A severely weakened immune system is a special case, for example after an organ transplant. Here EBV can cause serious problems, up to and including certain forms of lymph node cancer (lymphomas).^² In the long term, EBV has also been linked to multiple sclerosis. For the individual, this is no cause for concern: almost everyone carries the virus, and only very few people develop such diseases.

3. Symptoms, timeline and warning signs

The typical symptoms

• Severe sore throat — the tonsils are often very swollen and covered with a greyish-white coating, and the voice sounds thick and muffled. Swallowing can hurt so much that drinking becomes difficult; see sore throat.^¹
• Swollen lymph nodes — usually on both sides of the neck, typically at the back of the neck as well; more under swollen lymph nodes.
• Fever — often high, usually settling within ten to 14 days.^¹
• Marked fatigue — along with headache, muscle aches and aching limbs.
• Enlarged spleen and liver — the spleen is enlarged in around half of those affected; slightly raised liver values are common and usually return to normal within three to four weeks.^¹ Jaundice is rare.
• Other signs — swollen eyelids, pinpoint bleeding on the palate (petechiae), sometimes a skin rash.^³ A rash after taking amoxicillin is a special case — see section 7.^⁴

The timeline

There are usually several weeks between infection and the first symptoms — which is why it is rarely possible to say who you caught it from.^³ It often starts non-specifically with fatigue and headaches, followed by fever and a sore throat. The sore throat is at its worst in the first three to five days and then eases over roughly one to two weeks. The acute illness usually lasts two to three weeks; the increased tendency to tire can persist for weeks to months.^¹

4. Cause, transmission and medicines

• Pathogen: the Epstein-Barr virus, also known as human herpesvirus 4. It infects the lining of the throat and certain white blood cells (B lymphocytes); the immune response to this causes a large part of the symptoms.^³
• Spread through saliva: mainly through kissing — hence the nickname “kissing disease” — but also via shared glasses, bottles or cutlery.^²
• Long shedding: after the illness, the virus can still be found in saliva for months. Healthy people who had the infection long ago also shed it from time to time — often without knowing.^¹ Strict isolation is therefore neither necessary nor effective.
• Immune system weakened by medicines: immunosuppressants after transplants, high-dose cortisone or certain medicines for rheumatic conditions and cancer can make EBV more severe or cause it to become active again in the body.^²

5. Diagnosis: glandular fever or strep throat?

The suspicion is often obvious after questions and an examination. The diagnosis is confirmed with a blood test — with one caveat: in the first week of illness, some tests still come back negative.^¹,²

• Consultation and examination: the throat, lymph nodes, spleen and liver are examined by touch. Important: which medicines have you taken in the last few weeks, including antibiotics?
• Strep test: it helps to identify bacterial tonsillitis. A positive result does not rule out glandular fever, though — some people carry streptococci in their throat without them being the cause of the symptoms.
• Blood count: an increased number of conspicuously altered lymphocytes is typical. This supports the suspicion but does not prove it on its own.^¹
• Rapid EBV test: a positive test confirms the diagnosis. In the first week and in children, it is more often still negative.^¹
• EBV antibodies: measuring VCA IgM, VCA IgG and EBNA distinguishes a recent infection from a past one. The test is most informative from the second week of illness.^¹
• Liver values and ultrasound: show how much the liver and spleen are involved.
• Considering other causes: a similar picture can be caused by cytomegalovirus, toxoplasmosis or a recent HIV infection, for example. An HIV test for unexplained mononucleosis is not a sign of mistrust but of thoroughness.^³

Bring a complete list of your medicines to the appointment, including cold remedies and painkillers from the pharmacy. How to prepare well is explained in the guide Prepare for a doctor's appointment; what individual lab values mean is covered in Understanding blood values.

6. Treatment: what helps — and what does not

The honest answer first: there is no treatment against the Epstein-Barr virus itself that noticeably shortens the illness. Treatment relieves the symptoms until the immune system has the infection under control — and it keeps an eye out for the rare complications.^¹,²,³ Which measures are right for you is decided by the treating practice.

7. Painkillers, the liver and the amoxicillin trap

Paracetamol or ibuprofen?

Both are options, and with glandular fever each has one point you should watch out for:

• Paracetamol: the liver is often involved in mononucleosis. The maximum daily dose stated in the package leaflet therefore applies especially strictly — and paracetamol is also contained in many combination cold remedies. Taking two products with the same active ingredient is an avoidable mistake. If liver values are markedly raised, the practice will clarify whether paracetamol is suitable and how much.
• Ibuprofen: relieves a sore throat and fever well. If you are barely drinking because swallowing hurts, anti-inflammatory painkillers put more strain on the kidneys — drinking is part of the treatment here. If you have stomach problems or take blood thinners, check with your practice first.
• No aspirin for children and teenagers: in this age group, acetylsalicylic acid can trigger Reye's syndrome during feverish viral infections — a rare, dangerous condition with liver and brain damage. And this is precisely the age group most often affected by glandular fever.

Why the liver and kidneys generally matter with painkillers is explained in the guide Medications, kidneys and liver.

The amoxicillin trap

Because glandular fever and strep throat are so similar, some people are initially given an antibiotic. If it is amoxicillin or ampicillin, mononucleosis frequently leads to an extensive, itchy, blotchy rash. The Summary of Product Characteristics (SmPC) therefore advises avoiding amoxicillin if mononucleosis is suspected.^⁴ Exactly how often the rash occurs is disputed: older figures cite the large majority of those affected, more recent observations considerably fewer.^¹

According to current understanding, this rash is usually not a classic, permanent penicillin allergy, but a reaction arising from the interplay between the virus and the drug. Even so, you should not judge it yourself. Have the practice document what happened — a photo helps — and later clarify specifically whether there really is an allergy. A “penicillin allergy” recorded too hastily means that for future infections you will often be given broader-spectrum antibiotics that are less well tolerated. This also fuels antibiotic resistance.

8. When the exhaustion persists

The question many people ask most often is: why am I still so tired after weeks? The answer is unspectacular: for some of those affected, this is part of the normal course. Increased tiredness and reduced stamina can persist for weeks to months, even when the fever and sore throat are long gone.^¹,²

What helps

• Pace your energy — spread tasks across the day and plan breaks before you are exhausted.
• Build up gradually — better to return to school, university or work in stages than to go from zero to a hundred.
• Keep a record — a short daily energy log shows whether things are improving and is worth more at a follow-up appointment than anything you can remember.

When you should have things checked further

If the exhaustion has not improved after a few months, or if you regularly feel much worse after physical or mental exertion — often only after a delay of a day — this should be checked by a doctor. EBV infection is one of the known triggers of ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome). Its hallmark is exactly this worsening after exertion.^⁵ Similar patterns are known from long COVID.

If ME/CFS is suspected, the rule is: do not force exertion. Rigidly “training against the tiredness” can do harm when there is exercise intolerance. The approach belongs under medical supervision. At the same time, it is worth checking for other treatable causes — such as iron deficiency anaemia, an underactive thyroid, depression or medicines that make you tired.

9. Spleen, sport and the way back

In mononucleosis the spleen is often enlarged, and its capsule is taut and more vulnerable. A ruptured spleen is very rare but can be life-threatening — caused by knocks, falls or strong straining, and in isolated cases even without any obvious reason.^¹,²

How long the break from sport should last is not backed by studies — and recommendations vary accordingly. The German GP guideline advises avoiding strenuous physical exertion and contact sports for three to four weeks.^¹ The German federal health portal recommends a break of at least four to six weeks from sport and physical exertion.^² The best time to return is something to discuss with your practice — if necessary after an ultrasound check of the spleen.

• Everyday activities and short walks are usually possible early on, as you feel able, once the fever has gone.
• Contact and combat sports, ball sports, horse riding and heavy strength training only after explicit clearance — blows to the abdomen and strong straining are the main risk.
• Competitions and intensive endurance training come last and in stages — your fitness often takes longer to recover than your spleen.

10. Everyday life with glandular fever

• School, university, work: unlike chickenpox or scarlet fever, glandular fever does not come with a legal ban on attending under the German Infection Protection Act. You can go back once you are free of fever and feel up to it; a gradual return is often more realistic.
• Share nothing: do not share glasses, bottles or cutlery during the acute phase, and avoid kissing. There is no way to fully protect the people around you, because many of them already carry the virus anyway.
• Pause alcohol: as long as liver values are raised, alcohol is an additional strain. What alcohol does in combination with medicines is explained in the guide Medications and alcohol.
• Dose correctly for children: give children fever and pain medicines according to body weight, and no aspirin. Tips in the guide Medications for children.
• Put everything on one list: including lozenges, cold remedies and supplements. That way duplicate active ingredients stand out; instructions under Keeping a medication list.

Weeks of recovery under control — with brite

Painkillers without duplicates, energy and progress documented. Free.

Get started now