Tonsillitis: Symptoms, Assessment, Treatment and Red Flags

Most people have experienced a sore throat, but not every sore throat is tonsillitis. Tonsillitis means inflammation of the tonsils, usually caused by an acute infection. It is particularly common in children and young people, although adults can also be affected. For student nurses, the important part is not simply recognising a red, painful throat. It is understanding what is happening, assessing the whole patient and recognising when an apparently straightforward infection may need escalation.

What are the tonsils?

The palatine tonsils are paired collections of lymphoid tissue at the back of the oropharynx. They form part of Waldeyer's ring, together with the pharyngeal tonsil (adenoid), lingual tonsils and tubal tonsils. This ring of lymphoid tissue samples microorganisms entering through the nose and mouth and contributes to the immune response.

The tonsillar surface contains folds called tonsillar crypts. These increase contact between inhaled or swallowed material and immune tissue. B lymphocytes, T lymphocytes and antigen-presenting cells within the tonsils help recognise antigens and coordinate immune responses (Abbas, Lichtman and Pillai, 2023; Mescher, 2024).

What happens in tonsillitis?

Tonsillitis develops when infection triggers an inflammatory response within the tonsillar tissue. Immune cells release inflammatory mediators, local blood vessels dilate and vascular permeability increases. Fluid and immune cells move into the affected tissue.

This explains many of the clinical features. Vasodilation contributes to erythema, tissue oedema causes enlarged tonsils and inflammatory mediators stimulate pain receptors, producing a sore throat and pain on swallowing. The cervical lymph nodes may become enlarged and tender as the lymphatic system responds to infection.

In simple terms:

infection → immune activation → inflammation → swollen, erythematous tonsils → pain and difficulty swallowing

What causes tonsillitis?

Acute sore throat, including tonsillitis, is commonly viral and is usually self-limiting. Bacterial infection is also possible. The bacterial organism most often considered clinically is Streptococcus pyogenes, also known as group A streptococcus (GAS) (NICE, 2018).

The appearance of the throat alone cannot reliably distinguish a viral infection from a bacterial one. Tonsillar exudate can occur with bacterial infection, but clinical findings need to be considered together rather than treating one sign as diagnostic.

What might the patient present with?

A patient with acute tonsillitis may report a sore throat, painful swallowing, fever, headache, malaise or reduced oral intake. On examination there may be enlarged erythematous tonsils, tonsillar exudate and tender cervical lymphadenopathy.

Symptoms such as cough, coryza or other features of an upper respiratory tract infection can support a viral cause, although no single symptom provides a definitive diagnosis.

Assessment: look beyond the throat

For a student nurse, assessment should begin with the patient rather than the tonsils. Consider the patient's general appearance, airway, breathing, circulation, temperature, hydration, pain, ability to swallow and ability to manage oral secretions. Record observations and use the appropriate local early warning score where indicated.

Ask about the onset and duration of symptoms, fever, swallowing difficulty, oral intake, urine output, medication already taken, allergies and relevant medical history. Also establish whether symptoms are improving or deteriorating.

A patient who is alert, drinking and managing their secretions presents very differently from someone who is unable to swallow fluids, drooling, becoming dehydrated or developing airway symptoms.

FeverPAIN and Centor scores

In UK practice, NICE recommends clinical scoring systems such as FeverPAIN or Centor to help estimate the likelihood of streptococcal infection and support antibiotic prescribing decisions. They do not replace clinical judgement (NICE, 2018).

FeverPAIN considers five features: fever during the previous 24 hours, purulence, attendance within three days of symptom onset, severely inflamed tonsils and no cough or coryza. Each feature scores one point.

Centor considers tonsillar exudate, tender anterior cervical lymphadenopathy, history of fever and absence of cough. Again, these findings are used collectively to estimate the likelihood of streptococcal infection.

The important learning point is that these scores support decisions about antimicrobial treatment. A high score does not mean that the nurse has independently diagnosed bacterial tonsillitis, and prescribing decisions remain within the appropriate clinician's scope of practice.

Treatment

Most acute sore throats improve within about one week without antibiotics. Management therefore often focuses on symptom relief and maintaining hydration. NICE advises simple analgesia such as paracetamol or, where suitable, ibuprofen, alongside adequate fluid intake (NICE, 2018).

Antibiotics are not routinely required for every patient. NICE recommendations use clinical assessment and FeverPAIN or Centor scores to identify patients who are unlikely to benefit from antibiotics, those for whom a back-up prescription may be appropriate, and those in whom immediate antibiotics may be considered. Patients who are systemically very unwell or at increased risk of complications require individual clinical assessment (NICE, 2018).

This approach matters because unnecessary antibiotic use exposes patients to adverse effects without benefit and contributes to antimicrobial resistance.

Complications: when tonsillitis is no longer straightforward

One important complication is peritonsillar abscess, commonly called quinsy. Infection spreads into the tissues adjacent to the tonsil and an abscess forms. A patient may develop severe, often unilateral throat pain, worsening difficulty swallowing, a muffled or altered voice, drooling, trismus or visible asymmetry around the tonsillar area. This requires urgent clinical assessment because infection and swelling can threaten the airway or spread into deeper neck tissues.

Other complications of severe infection can include dehydration and spread of infection beyond the tonsils. The clinical priority is therefore recognising deterioration rather than assuming every sore throat will remain uncomplicated.

Red flags requiring urgent escalation

Escalate urgently if the patient develops signs of airway compromise, stridor, significant breathing difficulty, inability to swallow or manage secretions, drooling, severe dehydration, rapidly worsening symptoms, marked unilateral swelling, trismus, a muffled voice, significant systemic illness or other features that cause concern.

In an acutely deteriorating patient, use an ABCDE approach, obtain appropriate observations and seek senior or emergency clinical support according to local policy.

Student nurse scenario

Imagine you are caring for a young adult admitted with a severe sore throat. They were previously drinking small amounts but now tell you swallowing has become much more painful. You notice they are reluctant to speak, their voice sounds different and they are struggling to swallow their saliva.

The important action is not to wait for the next routine observation round or simply offer another drink. Reassess the patient, consider airway and breathing first, obtain observations and escalate promptly. The change in swallowing and voice raises concern for a complication such as peritonsillar infection and potentially evolving airway compromise.

This is the difference between recognising the diagnosis and nursing the patient: you are watching for what is changing.

Key points for student nurses

• Tonsillitis is inflammation of the tonsils, most commonly associated with acute infection.
• Many acute sore throats are viral and resolve without antibiotics.
• Throat appearance alone cannot reliably determine whether an infection is viral or bacterial.
• FeverPAIN and Centor support assessment of the likelihood of streptococcal infection and antibiotic decisions.
• Assess hydration, swallowing, secretions and the patient's overall clinical condition, not only the throat.
• Recognise possible quinsy and airway red flags early and escalate deterioration promptly.

References

• Abbas, A.K., Lichtman, A.H. and Pillai, S. (2023) Basic Immunology: Functions and Disorders of the Immune System. 7th edn. Philadelphia, PA: Elsevier.
• Mescher, A.L. (2024) Junqueira's Basic Histology: Text and Atlas. 17th edn. New York: McGraw Hill.
• National Institute for Health and Care Excellence (NICE) (2018) Sore throat (acute): antimicrobial prescribing. NICE guideline NG84. Available at: NICE NG84.
• NHS (2023) Tonsillitis. Available at: NHS.
• National Institute for Health and Care Excellence (NICE) (2025) Clinical Knowledge Summaries: Sore throat – acute. Available at: NICE Clinical Knowledge Summaries.
• Resuscitation Council UK (2024) The ABCDE approach. London: Resuscitation Council UK. Available at: Resuscitation Council UK.