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Mononucleosis (Mono)

By Bjarne Lühr Hansen PhD, MD and Philipp Skafte-Holm MD, Mentor Institute

Mono is a viral infection. The illness is especially seen with teenagers and adults. It appears as fever, a sore throat and swollen lymph glands. You should consider mono is you have prolonged and severe tonsillitis. There is no treatment for the illness. In far the most cases, the illness is benign. You must call the doctor immediately, if you have trouble breathing or it you suddenly have stomach pains and feel like you are going to faint.

Mono is tonsillitis caused by a certain virus – called the Epstein-Barr virus. The illness is seen with teenagers and young adults – typically in the age of 15 to 25 years. It is a very common illness, thus the majority of all adults more than 25 years old will have had mono. You can only have mono once in a lifetime.

The illness starts with tiredness, a sensation of being ill, muscle pains all over the body, a tendency to sweating and headache – almost like influenza. 1 to 2 weeks later, fever and pains in the throat follow that worsen as you swallow together with swollen lymph glands. The fever is around 39 to 40 degrees and can last up to 3 weeks. Most often, it lasts 1 week. Pain on swallowing is conspicuous and makes it difficult to eat and drink. When you have mono, you feel really ill and prefer to stay in bed and sleep.

The swollen lymph glands can feel like sore lumps the size of peas on the neck, in the neck and sometimes in the armpit and the groin. If you look into the mouth, you can see that the tonsils are big with thick white coatings. Approximately one in every ten with mono has a big rash or red spots on the chest.

There is only one way to find out whether you have mono – and that is with a blood sample. To be sure that the sample reaches the right answer, it must be taken after you have been ill for at least 1 week. If the blood sample has been taken before that, it is useless.

In far the most cases, mono is no serious illness. However, it takes a long time (2 to 4 weeks) before you have fully recovered from mono. Especially the fever and the tiredness are lengthy. In many was, mono is similar to regular tonsillitis – only, you are ill for a longer time and feel more ill, when you have mono. Therefore, you should consider mono if your tonsillitis lasts long (more than 1 week) or if you feel very ill.

When you have mono, the liver is almost always affected. This is apparent in the presence of elevated transaminases in the blood. The affect on the liver passes by itself and is not dangerous. It is not necessary to keep track of the elevated transaminases with repeated blood samples – the liver is not harmed by it.

In very rare cases, complication with mono may arise:

Closing of the throat is a very rare but of course feared complication of the illness. Closing of the throat appears when you cannot breathe.

Bursting of the spleen is a dramatic but very rare complication of mono. If this should happen, you will have stomach pains and feel like you are going to faint. Only occurs the first 3 weeks after the illness has started. The spleen can burst during rest as well as during physical activity. Therefore, it does not make sense to cease all physical activity for a longer period but violent sports with close contact like martial arts is advised against for 1 month after mono.


The illness transmits through the transfer of spit. A lot of spit has to be transferred – as is the case when you French kiss someone. It takes 30 to 45 days from you have been infected till you fall ill – this is a long time.

When can I go to work?
It depends on how ill you become. You should not go to work before you are completely free of fever and it can take from 1 to 3 weeks.


Antibiotics do not help. Ordinary painkilling medication and antipyretics can soothe the nuisances.

What can you do?

There is no effective treatment for mono. Take it easy until the temperature is normal. Make sure to drink plenty. It is not sensible to cease all physical activity for a longer period but violent sports with close contact like martial arts is advised against for 1 month after mono. You can enjoy alcohol as usual.

Contact the doctor tomorrow

If you believe you have mono.

Contact the doctor immediately

If you have trouble breathing. If you suddenly have stomach pains and feel you are going to faint.