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

Most often, tonsillitis is caused by a virus and should not be treated with penicillin. Your doctor can determine whether bacteria cause the tonsillitis and whether you need treatment with penicillin. Mono (mononucleosis or glandular fever) should be suspected in the case of tonsillitis that lasts longer than 1 week.

Tonsillitis is frequent with younger adults and is caused by either virus or bacteria. Far the most common cause of tonsillitis is virus. Only one in every fifth case of tonsillitis with adults is caused by bacteria and should be treated with penicillin.

Mono (mononucleosis or glandular fever) that is caused by a virus is a more rare form of tonsillitis. You can only have mono once in a lifetime. The illness cannot be treated with antibiotics.

Viruses that cause tonsillitis occur especially during the winter. First the throat becomes irritated. Then, light pains in connection with swallowing, rise in temperature to around 38,0ºC, closeness in the nose and possibly the nose runs with a thin secrete together with a cough. It appears as a common cold with a sore throat. Your throat becomes red and on the outside of the throat small sore lumps appear. Sometimes you will be able to see white spots on the tonsils. There is no treatment for the illness and antibiotics do not help. The illness passes by itself after some days but can possibly be relieved by painkilling medication bought over the counter.

If bacteria cause the tonsillitis, the nuisances are worse. Often, the temperature is high, meaning more than 38.5ºC (see Fever). You become more ill and prefers to stay in bed. The pains in the throat are aching that worsen when you swallow. Usually, there is no running nose or cough. Your throat becomes crimson red and the tonsils increase heavily in size with greyish spots. It can be hard to distinguish between a viral and a bacterial attack. By a grafting from your throat and/or a blood sample, your doctor can quickly determine whether bacteria cause the tonsillitis and you should be treated with antibiotics.

Scarlet fever is tonsillitis caused by a certain bacteria that causes a rash. The rash begins in the face and later spreads to neck, chest and arms. The rash looks like ‘goose pimples’ but is completely red. You can feel the ‘goose pimples’. Scarlet fever can be treated with antibiotics. After you have taken antibiotics for 2 days, you will be free of fever and feel much better.

Mono (mononucleosis or glandular fever) is a type of tonsillitis that especially occurs with larger children and teenagers. The first signs of mono is tiredness, muscle pain and headache for a couple of weeks. Hereafter, there is fever, pains in connection with swallowing and swelling on the neck. The tonsils are heavily increased in size with thick, white confluent spots. The illness lasts around 2 to 4 weeks. Most often, mono is discovered by the tonsillitis not improving after around a week. With a blood test, your general practitioner can determine whether you have mono. There is no treatment for mono.


Depends on what type of tonsillitis you have. A viral tonsillitis is highly contagious, since virus is transmitted from person to person through the air. Bacteria are less contagious than viruses. Most frequently, the contagion is transmitted by direct contact and not through the air. In the case of mono, a considerable amount of spit is must be transferred for the illness to infect – this is why the illness is also called kissing disease.

When can I go to work?
When you are free of fever.


To soothe the pains, you can take painkilling medication (aspirin, paracetamol or ibuprofen) up to 3 to 4 times a day. Only tonsillitis that is caused by bacteria should be treated with antibiotics. Scarlet fever should be treated with antibiotics. There is no treatment for mono.

What can you do?

In the case of high fever, you should dress lightly, stay in a cool room and drink plenty of fluids. If yo have mono, you should avoid heavy physical activity (e.g. running a marathon or elite sports) for 3 months, while regular exercise is still recommended.

Contact the doctor tomorrow

If you have more than 38.0ºC, heavy pains in connection with swallowing and you throat is red. If you suspect scarlet fever. If you receive penicillin for tonsillitis and after 2 days you still have a fever and a sore throat. If your throat is sore for more than one week.

Contact the doctor immediately

If you have mono and you have stomach pains. If you have trouble breathing.