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7-year-old Amy comes in complaining of a sore throat and feeling sorry for herself.  She has pus all over his tonsils.

Should you treat her with antibiotics?

Bottom Line

Tonsillitis is usually viral

Treatment is mainly symptomatic (fluids, pain relief)

The main reason for antibiotics is in strep pyogenes to prevent the complication of rheumatic heart disease

The antibiotic benefit is only significant in high risk groups

Where are the tonsils?

The tonsils are a mass of lymphoid tissue found in the oropharynx. They are part of Waldeyer’s ring – the tonsils, adenoids and associated lymphoid tissue at the back of the throat. What we usually think of as tonsils are the palatine tonsils. You can find them between the palatoglossal arch anteriorly and the palatopharyngeal arch posteriorly. They are covered with several deep crypts. These increase the surface area exposed to foreign material (and are an excellent place for tonsil stones* to form).

Location of the tonsils in Waldeyer's ring

The tonsils look like a pair of almonds – ἀμυγδαλή, amygdalē, ‘almond – hence amygdalitis is another name for tonsillitis.

What do the tonsils do?

They are part of the body’s immune system and help to fight off infections by trapping and identifying potentially harmful bacteria and viruses that enter the body through the mouth or nose. As puberty hits, the tonsils start to involute; hence tonsillitis is much less common in adults.

What are the signs and symptoms of tonsillitis?

Local features

  • Sore throat
  • Ear pain
  • Odynophagia
  • Hoarse voice
  • Tonsillar-pharyngeal erythema or exudate
  • Soft palate petechiae
  • Cervical lymphadenitis

Systemic features

What causes a tonsillar exudate?

Tonsillar exudate is made up of lymphocytes and neutrophils mixed up with proteins. Unfortunately, its presence or absence does not help you determine the cause.

What is the difference between tonsillitis and pharyngitis?

Pharyngitis is simple inflammation and irritation of the throat – a sore throat, if you will. Patients are more likely to have coryzal symptoms, cough and conjunctivitis as well as GI symptoms – abdominal pain and diarrhoea.

What are the causes of tonsillitis?

Most cases of tonsillitis are viral. Group A Streptococcus is responsible for 10-20% of cases.

The predominant age is 4-11 years, and it is rare in <3 year olds.

Due to concerns about potential non-suppurative complications of strep infection, such as rheumatic fever and glomerulonephritis, many kids get unnecessary antibiotic prescriptions.

Pus on the tonsils does not mean it’s bacterial!

What are some viral causes of tonsillitis?

The most commons viruses causing tonsillitis/pharyngitis are rhinovirus; coronavirus; adenovirus; herpes simplex; parainfluenza; echovirus; coxsackie A; Epstein-Barr; CMV.

Epstein-Barr Virus (EBV)

In EBV, the patient presents with malaise, headache and fever, exudative pharyngitis, posterior cervical node enlargement, splenomegaly, and hepatomegaly.

Diagnosis is clinical and by Monospot (heterophile antibody).  EBV immunoglobulin, atypical lymphocytes on the film and liver enzyme derangement can also be seen.

The morbilliform rash of EBV plus amoxicilli

Although 5% of the general population develop an ‘amoxicillin rash’, this increases to 90% in patients with EBV. This usually develops a few days after starting amoxicillin. It is a maculopapular or morbilliform rash that begins on the trunk.

Treatment of EBV is supportive, with IV fluids and pain relief if needed. They should avoid contact sports for six weeks to reduce the chance of the spleen exploding.

CMV Tonsillitis

This is similar to EBV, so it should be considered if EBV-like symptoms persist but the Monospot remains negative.  Fevers and malaise are the predominant symptoms, with less cervical lymphadenopathy and splenic enlargement than in EBV.  Immunoglobulin (IgM and IgG) testing can confirm the diagnosis.

HIV Tonsillitis

HIV is uncommon in children but should be considered in adolescents with high-risk behaviours.  Pharyngitis is the presenting complaint in 50-70% of patients (often presents like EBV pharyngitis).

Factors that point towards HIV tonsillitis are the absence of exudate; tonsillar hypertrophy; rash; mucocutaneous ulceration.

Consider candida and mycobacterium in the immunocompromised patient.

What are some bacterial causes of tonsillitis?

Group A beta-haemolytic strep

Strep pyogenes, or Group A beta-haemolytic strep (GABHS), is the most common bacterial cause (15-30%). Hence the term Strep throat.  It is rare in children under two years of age.

It’s worth considering diphtheria in unvaccinated patients.

How can I determine if it is bacterial or viral?

There are two scoring systems for assessing the likelihood of GABHS and helping with your risk stratification.

Centor Criteria

If 4 of the Centor criteria are met, PPV is 60%. The absence of 3 or 4 of the Centor criteria has a fairly high NPV of 80%. The recommendation is to treat with 4, don’t treat with 0-1, culture with 2 and think about treatment with 3.

The modified Centor criteria give you another point if you are between 3 and 14 years old.

History of fever >38°C

Tonsillar exudate

Tender anterior cervical adenopathy

Absence of cough

Streptococcal Score Card

Season = late autumn, winter, early spring

No symptoms of a viral upper respiratory infection (conjunctivitis, rhinorrhoea, or cough). If 5 of the criteria are met, a positive culture for GABHS is predicted in 59% of children; if 6 of the criteria are met, a positive culture is predicted in 75% of children.

5 to 15 years

Season (late autumn, winter, early spring)

Fever (≥38.3°C)

Cervical lymphadenopathy

Pharyngeal erythema, oedema, or exudate

Testing for GABHS

Rapid Strep test

Rapid antigen testing can be performed at the bedside. Depending on manufacturer, it has a specificity of 88 to 100% but a sensitivity of around 61 to 95%.

How long does tonsillitis last?

GABHS has a 3-4 day natural history and is self-limiting.

How do we treat tonsillitis?

As most cases are viral, antibiotics won’t make any difference. Patients need symptomatic relief and supportive treatment. This means antipyretics/analgesia and hydration.

Why do we prescribe antibiotics?

The aims of antibiotic therapy in bacterial tonsillitis are:

Studies show that antibiotics shorten the course of the illness by about 16 hours.

What about steroids in sore throats?

de Cassan, S., Thompson, M.J., Perera, R., Glasziou, P.P., Del Mar, C.B., Heneghan, C.J. and Hayward, G., 2020. Corticosteroids as standalone or add‐on treatment for sore throat. Cochrane Database of Systematic Reviews, (5).

This Cochrane review, updated in 2020, combined adult and paediatric research. Children accounted for 369 of the 1319 participants across nine trials. They came up with an NNT of 5 to stop pain by 24 hours. Adverse events were few and far between, but the quality of reporting was poor. They might also be useful in peritonsillar and retropharyngeal abscesses.

What are the complications of tonsillitis?

Suppurative complications

NNT to prevent surgical intervention from complications is 200.

NNT to prevent quinsy is uncertain but actually, evidence suggests that many of these presents without a sore throat.

Peritonsillar abscess or quinsy

As pus collects between the pharyngeal constrictor muscles and the capsule of the tonsil, an abscess forms. Patients may present with trismus, drooling and a hot-potato voice. If you can see the oropharynx, you might see a unilateral bulging tonsil with uvula deviation. The treatment is generally surgical with incision and drainage.

You can confirm the diagnosis with a bedside ultrasound.

Only 20-30% have a prior history of tonsillitis, but 100% present with concomitant acute tonsillar infection.

Case courtesy of The Pocus Atlas

Retro-pharyngeal abscess

If the infection spreads beyond the tonsillar capsule posteriorly, it can form an abscess space between the posterior pharyngeal wall and the pre-vertebral fascia. Just like other cases of tonsillitis, children may complain of odynophagia and difficulty opening their mouths (trismus). Unlike in cases of a peritonsillar abscess, you may not see anything when you look at the back of the throat. A lateral soft tissue x-ray of the neck (or a CT scan) might confirm the diagnosis.

Case courtesy of Maulik S Patel, From the case rID: 13128

Cervical lymphadenitis



Otitis media 

We’ve got a whole blog post on otitis media here.

Lemierres syndrome

This is thrombosis of the internal jugular vein, most often becasue of infection by Fusobacterium necrophorum, seeding from the tonsils.

Non-suppurative complications

There is no definitive evidence that antibiotics prevent glomerulonephritis.

Some evidence for antibiotics preventing rheumatic heart disease (but this was in American Marines in the 1950s).  NNT to prevent rheumatic heart disease was 63.

Group A strep can also cause post-streptococcal glomerulonephritis. This is an immune-mediated response and so antibiotics make no difference to the course of the disease.

What about rheumatic fever?

It is now rare, and the incidence is <1 in 100,000.

Of those who do get it, only one-third get carditis and of these, only a small minority get valve dysfunction.

So who should I treat?

Antibiotics are only required in high-risk populations to prevent rheumatic heart disease. They do very little to relieve the actual presenting complaints. They may reduce the duration of symptoms by 12 to 24 hours only.

This has to be balanced against the risk of allergy (severe penicillin allergy seen in 10-40 per 100,000), rashes and antibiotic resistance.

In many countries, treatment is not recommended.

High-risk populations

Patients aged 2-25 with sore throat in communities with a high incidence of acute rheumatic fever (some Indigenous communities in northern Australia and also some lower socio-economic communities)

Patients of any age with existing rheumatic heart disease

Patients with scarlet fever

If treatment is given:

Phenoxymethylpenicillin (15 mg/kg up to 500mg BD for 10 days)

Roxithromycin would be the second line treatment

Some centres use a single dose of glucocorticoid to decrease pain and swelling

What about recurrent or chronic tonsillitis?

Recurrent tonsillitis is five or more tonsillitis episodes in one year. It’s worth considering primary immunodeficiency in children who seem to suffer more than the average.

*What the heck are tonsil stones?

Tonsil stones, or tonsilloliths, are yellow/white concretions of white blood cells, that collect in the deep crypts of the tonsil. They can lead to pain and bad breath.


Ahmed, K., Jones, A.S., Shah, K. and Smethurst, A., 1994. The role of ultrasound in the management of peritonsillar abscess. The Journal of Laryngology & Otology108(7), pp.610-612.

Anderson, J. and Paterek, E., 2022. Tonsillitis. In StatPearls [Internet]. StatPearls Publishing.

BMJ Best Practice, Tonsillitis

Centor, R.M., Witherspoon, J.M., Dalton, H.P., Brody, C.E. and Link, K., 1981. The diagnosis of strep throat in adults in the emergency room. Medical Decision Making1(3), pp.239-246.

Guthrie K, My throat hurts, Life in the Fast Lane

Hayward, M. Thompson, R. Perera, P. Glasziou, C. Del Mar and C. Heneghan, “Corticosteroids as standalone or add-on treatment for sore throat.,” Cochrane Database Systematic Review, vol. 17, no. 10, 2012.

Hsieh, T.H., Chen, P.Y., Huang, F.L., Wang, J.D., Wang, L.C., Lin, H.K., Lin, H.C., Hsieh, H.Y., Yu, M.K., Chang, C.F. and Chuang, T.Y., 2011. Are empiric antibiotics for acute exudative tonsillitis needed in children?. Journal of Microbiology, Immunology and Infection44(5), pp.328-332.

Krebs, M Strep Throat Mimics: Pearls & Pitfalls

McIsaac, W.J., Kellner, J.D., Aufricht, P., Vanjaka, A. and Low, D.E., 2004. Empirical validation of guidelines for the management of pharyngitis in children and adults. JAMA, 291(13), pp.1587-1595.

Pearce JM. Amygdala. European Neurology. 2008 Apr 1;59(5):283.

Pelucchi, C., Grigoryan, L., Galeone, C., Esposito, S., Huovinen, P., Little, P. and Verheij, T., 2012. Guideline for the management of acute sore throat: ESCMID Sore Throat Guideline Group. Clinical microbiology and infection18, pp.1-28.

Roggen I, van Berlaar G, Gordts F, Pierard D, Hubloue I, Centro criteria in children in a paediatric emergency department for what it is worth. BMJ Open, 2013;3::e002712. doi:10.1136/bmjopen-2013-002712



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5 thoughts on “Tonsillitis”

  1. Great summary.

    For those in the northern hemisphere there is NICE guidance on the subject as well. (CG69 – Respiratory Tract Infections )