Red flag symptoms: Pharyngitis

Symptoms that may indicate significant pathology in patients presenting with sore throat, questions to ask, and when to refer.

Examine the pharynx and look for signs of tonsil enlargement
Examine the pharynx and look for signs of tonsil enlargement

Red flag symptoms

  • Persistent sore throat for > 6 weeks
  • Excessive drooling
  • Trismus
  • Unilateral facial swelling
  • Dysphagia
  • Dyspnoea
  • Immunosuppressant medication such as carbimazole
  • Persistent unilateral tonsillar enlargement
  • Neck stiffness
  • Photophobia
  • Non-blanching rash

Pharyngitis is a common primary care presentation and the majority of cases are self-limiting viral URTIs, although rarer causes of sore throat need to be excluded.

It is important to know why the patient has presented now and what their ideas, concerns and expectations are. Despite multiple media campaigns and public advertisements, a lot of patients still may feel an antibiotic is required. This may be an appropriate time to educate your patient in the appropriateness of antibiotics for self-limiting viral illnesses, and also to undertake some opportunistic health promotion such as smoking cessation advice.


History needs to be focused and will largely depend on the duration of the symptoms. A short history will be more focused around infective pathology and a longer history may prompt the clinician to enquire around more sinister aetiologies.

Questions to ask include the following:

  • How long have the symptoms been present?
  • Have they got worse?
  • Has the patient noticed any associated symptoms such as cough, dyspnoea, high temperatures, neck stiffness, or photophobia?
  • Are they having any difficulties swallowing?
  • Are they having any difficulties in opening their mouth?
  • Have they had a look in their own throat and noted anything unusual such as swollen tonsils, pus on the tonsils or any new lesions on the palate?
  • Are there any unilateral symptoms?
  • Have they had these symptoms before?
  • Is there a history of reflux at all?
  • Is there a history of asthma for which the patient takes inhalers? If so, do they rinse their mouth post-use?
  • Does the patient smoke or drink much alcohol?
  • Have they noticed sneezing or itchy eyes?

A drug history may be relevant to ensure patients are not taking any significant medications such as carbimazole or any other immunosuppressants. Inhalers could be a cause of persistent sore throat.


Look for signs of any respiratory distress. Is the patient having any difficulty opening their mouth? Is there any drooling or significant airway compromise?

Look for signs of sepsis, such as hypotension, tachycardia, and pyrexia. Open the mouth and examine the pharynx. Look for signs of tonsillar enlargement. If present, is this bilateral or unilateral? There are four grades of tonsillitis to be aware of (see box 1). Is there any exudate present on the tonsils? Examine the palate if relevant and ensure there is no other significant pathology such as thrush or abnormal lesions. Palpate for lymph nodes. If you suspect infectious mononucleosis, you may wish to palpate the spleen.

Box 1: grading of tonsillitis
Grade 1 - tonsils hidden within tonsil pillars
Grade 2 - tonsils extending to the pillars
Grade 3 - tonsils are beyond the pillars
Grade 4 - tonsils extend to midline

Primary care investigations

Most pharyngitis will not require any investigation although you may wish to consider the following investigations depending on what the history has revealed:

  • Full blood count - this may be relevant if you suspect neutropenia or infectious mononucleosis. Ensure you have a plan for how the results of the FBC will be managed. Will it fall into the out-of-hours service? If so, ensure this is handed over. If you suspect agranulocytosis, then you may wish to send the patient to hospital to have a FBC performed there
  • Monospot test
  • Throat swab
  • Helicobacter pylori faecal antigen test or serology (depending on your local policies for this)
  • HIV testing may be appropriate depending on the history and concern about seroconversion.

When to refer

Persistent unexplained sore throat for > 6 weeks will need a referral to ENT for further evaluation. If red flag symptoms are present then you may wish to refer on a two-week wait.

Same-day admission is needed if there is trismus, drooling or evidence of quinsy on examination.

Neutropenia noted on FBC will need admission.

Same-day admission is needed if there are symptoms suggestive of meningitis.

Persistent unilateral tonsillar enlargement will need referral on a two-week wait pathway.

Causes of pharyngitis

  • Non-specific viral infection
  • Bacterial tonsillitis (for example with streptococcus)
  • Viral tonsillitis
  • Tonsillar malignancy
  • Infectious mononucleosis
  • Quinsy
  • Thrush
  • HIV seroconversion illness
  • GORD
  • Latrogenic causes such as carbimazole
  • Hayfever

Treatment options

Treatment options depend on aetiology. Acute viral pharyngitis in the absence of red flags or significant examination findings should be managed conservatively with attention to symptom control. A good explanation of why antibiotics are not necessary, a discussion of the red flag symptoms and a discussion of when to expect resolution of symptoms should suffice. You may wish to consider a delayed prescription for antibiotics with a clear, well-documented discussion of when would be appropriate to use them.

You may also wish to consider the Centor criteria (presence of three or more of tonsillar exudate, tender anterior cervical lymphadenopathy or lymphadenitis, history of fever and an absence of cough) when considering whether an antibiotic prescription would be appropriate.1 This is a useful evidence-based tool for helping you negotiate a plan for the patient.

Persistent unilateral tonsillar enlargement may require biopsy under the care of ENT to exclude a malignant pathology.

Quinsy will require emergency ENT admission for drainage.

Suspected GORD will require initiation of the GORD pathway.

Confirmed infectious mononucleosis requires no specific treatment, other than an explanation to the patient of what to expect regarding resolution of the symptoms and potential complications such as splenomegaly. It would be appropriate to advise against contact sports for four weeks if relevant

  • Dr Singh is a GP in Northumberland

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  1. NICE Respiratory tract infections - antibiotic prescribing. London, NICE 2008.

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