Pharyngitis - red flag symptoms

Significant pathologies that need to be considered when patients present with sore throat include COVID-19, HIV and quinsy, writes Dr Pipin Singh.

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
  • Persistent cough, fever, loss of taste and loss of smell
  • 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, with the majority of cases being self-limiting viral upper respiratory tract infections (URTIs). However, less common causes of sore throat need to be excluded, including COVID-19.1 If you suspect COVID-19 infection, ask the patient to arrange a test and to follow the appropriate government advice around self-isolation.2

It is important to know why the patient has presented now, and what their ideas, concerns and expectations are. A lot of patients may still feel an antibiotic is required to treat an acute sore throat. This may be a suitable time to educate your patient in the appropriateness of antibiotics for self-limiting viral illnesses, and 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 on infective pathology and a longer history may allow enquiry around more sinister aetiologies.

Questions to ask include:

  • How long have the symptoms been present? Have they got worse?
  • Has the patient noticed any cough, dyspnoea, high temperatures, neck stiffness, or photophobia? Is there any loss of taste or smell?
  • Are they having any difficulty swallowing or 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? 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.

You may also wish to explore sexual history if you suspect that a sexually transmitted infection such as gonorrhea may be causing the symptoms. The patient’s occupation may also be relevant, for example, if they are a singer.

Guidance on examination

The COVID-19 pandemic has changed advice around when and how to perform throat examination. RCPCH guidance states that throat examinations in children are to be avoided if possible.3 You could ask your patient to take a picture of the back of their throat with a smart phone.

If you feel that you still need to examine a throat directly after exploring other options, then ensure you wear appropriate PPE.4

RCPCH guidance on tonsillar examination

  • Follow PHE guidance on taking a combined nose and throat swab for COVID-19 for throat examination; examine the oropharynx of children only if essential
  • Effective precautions can be taken by using droplet PPE (apron/gloves/surgical mask) with eye protection. This can be visor, goggles or safety spectacles. Visors should be available in primary care.
  • Where a diagnosis of tonsillitis is suspected on clinical history, the default remains not to examine the throat unless absolutely necessary.

Face-to-face examination

  • 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. You may also want to examine oxygen saturations.
  • 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 below). 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.

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 (FBC) — 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, for example, in a patient on carbimazole, then you may wish to send the patient to hospital to have an 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
  • Swab for gonorrhoea
  • COVID-19 test
  • Chest X-ray, if there are persistent respiratory symptoms

When to refer

Persistent unexplained sore throat for >6 weeks will need a routine referral to ENT for further evaluation. If red flag symptoms are present, then you may wish to refer on a 2-week wait.

Same-day admission is needed if there is trismus, drooling, or evidence of quinsy on examination, as well as when there are symptoms suggestive of meningitis.

Neutropenia noted on FBC will need admission.

Persistent unilateral tonsillar enlargement will need referral on a two-week wait pathway. Refer suspected gonococcal pharyngitis to your local genitourinary medicine (GUM) clinic

Causes of pharyngitis

  • Non-specific viral infection
  • Bacterial tonsillitis (for example with Streptococcus)
  • Viral tonsillitis
  • Infectious mononucleosis
  • Quinsy
  • Tonsillar malignancy
  • Thrush
  • Hayfever
  • HIV seroconversion illness
  • Gastro-oesophageal reflux disease (GORD)
  • Iatrogenic causes such as carbimazole
  • COVID-19
  • Occupations such as singing may make a person prone to a persistent sore throat
  • Pharyngitis secondary to gonococcus

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 (see box). Antibiotic choice and duration should be dictated by the antimicrobial policy of your local CCG or health board.

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 4 weeks, if relevant.

Suspected hay fever will likely require antihistamines, intranasal steroid spray and appropriate eye drops.

An occupational cause may require the input of speech and language therapy.

Thrush secondary to the use of steroid inhaled therapy may require education around appropriate mouth care after inhaler usage.


The FeverPAIN score has been shown to have slightly better validity than the Centor tool, which it has now largely replaced.5 FeverPAIN looks at presence of fever in the past 24 hours, absence of cough or coryza, and symptom onset within the past 72 hours.

Examination findings include inflammation of tonsils or purulent tonsils. A score of 1 suggests no antibiotics, at 2–3 consider a delayed prescription, and for a score of 4–5 consider an antibiotic prescription.

  • Dr Singh is a GP in Northumberland

This is an updated version of an article that was first published in 2016.

Click here to take a test on this article and claim a certificate on MIMS Learning


  1. WHO. Coronavirus. [Accessed 27 January 2021]

  2. Stay at home: guidance for households with possible or confirmed coronavirus (COVID-19) infection. Updated 19 January 2021.

  3. Royal College of Paediatrics and Child Health. COVID-19 guidance for paediatric services. Updated 11 January 2021.

  4. NHS England. COVID-19 infection prevention and control. Updated 21 January 2021.

  5. NICE. Sore throat (acute): antimicrobial prescribing. NG84.

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