Pharyngitis

Basics

Description

Acute or chronic inflammation of the pharyngeal mucosa
Group A Streptococcus (GAS) pharyngitis is notable for preventable suppurative (e.g., retropharyngeal or peritonsillar abscess) and nonsuppurative (e.g., rheumatic sequelae) complications
Synonyms: sore throat; tonsillitis; “strep throat”

Epidemiology

1–2% of all outpatient and 6% of all pediatric visits to primary care physicians
~50% of cases of acute pharyngitis occur <18 years of age, and incidence declines in adults after 40 years of age
- Low likelihood at <3-years-old
Most commonly viral (50–80% of cases)
GAS is the most common bacterial cause of acute pharyngitis, accounting for 15–30% of pediatric cases (with peak incidence in 7 to 8 year olds) and 5–15% of adult cases
Less common causes of pharyngitis include Fusobacterium necrophorum, non-GAS, and Neisseria gonorrhoeae if sexually active.
Rheumatic fever is a serious sequela but is rare in the United States (<1 case per 100,000). Early antibiotic use has reduced occurrence.
3,000 to 4,000 patients with GAS must be treated to prevent one case of acute rheumatic fever.

Pediatric Considerations
The highest incidence of rheumatic fever is in children 5 to 18 years old as a rare sequela of streptococcal pharyngitis.

Etiology and Pathophysiology

Acute, viral
- Most common pathogens: rhinovirus; adenovirus; coronavirus; enterovirus; influenza; parainfluenza virus; coxsackievirus; respiratory syncytial virus
- Less common pathogens: herpes simplex virus; Epstein-Barr virus (EBV); cytomegalovirus (CMV); HIV
Acute, bacterial (associated with higher fevers)
- Group A, C, or G Streptococcus
- N. gonorrhoeae; Corynebacterium diphtheriae (diphtheria); Haemophilus influenzae
- Moraxella catarrhalis; Chlamydia pneumoniae
- Fusobacterium necrophorum (20% young adult cases)
- Arcanobacterium haemolyticum; Mycoplasma pneumoniae; Francisella tularensis (tularemia)
Acute, noninfectious
- May be caustic, mechanical, or trauma-related
Chronic, more likely noninfectious
- Allergic rhinitis
- Gastroesophageal reflux disease (GERD)
- Smoking or smoke exposure
- Dry air exposure
- Vocal strain
- Medication side effects
- Neoplasms
- Vasculitis
- Radiation

Genetics

Patients with family history of rheumatic fever have a higher risk of rheumatic sequelae following an untreated GAS infection.

Risk Factors

Epidemics of GAS
Cold season (late fall through early spring)
Age (rheumatic fever possible, especially in children/adolescents 5 to 15 years)
Close contact with infected people
Immunosuppression
Smoking or smoke exposure
Allergic rhinitis
GERD
Oral sex
Recent illness
Chronic colonization of bacteria in tonsils/adenoids

General Prevention

Avoid close contact with infectious people.
Wash hands frequently.
Vaccinations
Avoid smoking or secondhand smoke.
Manage preventable causes (e.g., GERD, allergic rhinitis).

Diagnosis

Diagnosis is clinical, but suspicion for bacterial cause may warrant testing based on prediction rules.

History

Sore throat
Cough, coryza, and hoarseness (associated with viral infections)
Dysphagia/odynophagia
Rhinorrhea
Fever
Anorexia
Chills
Malaise; fatigue
Headache
Dysuria and arthralgias (suggesting gonococcal etiology)
Sick contacts with similar symptoms or confirmed diagnosis

Physical Exam

Enlarged tonsils with or without exudate
Pharyngeal erythema; palatal petechiae
Cervical adenopathy (anterior suggestive of GAS, posterior associated with infectious mononucleosis)
Fever (higher in bacterial infections)
More concerning findings
- Unilateral tonsillar swelling or uvular deviation (concern for peritonsillar abscess)
- Trismus; stridor; drooling (concern for peritonsillar/retropharyngeal abscess or epiglottitis)
- Neck stiffness or pain with neck extension (concerning for retropharyngeal abscess)
Associations with specific infections
- Pharyngeal ulcers (CMV, HIV, Crohn, other autoimmune vasculitides)
- Punctate erythematous macules with reddened flexor creases and circumoral pallor (Scarlet fever—GAS)
- Gray oral pseudomembrane suggests diphtheria or infectious mononucleosis (EBV/CMV).
- Characteristic erythematous-based clear vesicles (HSV or coxsackie A virus)
- Conjunctivitis (adenovirus)
- Hepatomegaly (EBV/CMV)

Differential Diagnosis

Viral infection, including acute HIV, EBV, and CMV
Streptococcal infection
Allergic rhinitis
GERD
Malignancy (lymphoma, squamous cell carcinoma)
Irritants/chemicals (detergent/caustic ingestion)
Atypical bacterial (e.g., gonococcal, chlamydial, syphilis, pertussis, diphtheria)
Oral candidiasis (patients typically complain of dysphagia)
Thyroiditis (can be painful or painless, possibly associated with hyperthyroid syndrome)
Epiglottitis (associated with stridor, drooling, and respiratory distress)
Referral from extrapharyngeal source (e.g., otitis media, dental abscess)
Foreign body

Diagnostic Tests & Interpretation

Prediction rules determine need for further testing (see below).
Testing is generally not needed with overt viral clinical features (e.g., cough, rhinorrhea, hoarseness, oral ulcers)
Avoid testing for GAS pharyngitis in children <3 years old as acute rheumatic flare is rare, unless there is a close sick contact who is GAS-positive.
Modified Centor (McIsaac) clinical prediction rule for GAS infection:
- +1 point: tonsillar exudates or swelling
- +1 point: tender anterior chain cervical adenopathy
- +1 point: absence of cough
- +1 point: fever by history
- +1 point: age <15 years
- 0 point: age 15 to 44 years
- −1 point: age >44 years
Scoring:
- 4 points: positive predictive value ~80%; treat empirically
- 2 to 3 points: positive predictive value ~50%, rapid strep antigen; treat if GAS-positive
- 0 or 1 point: positive predictive value <20%; do not test; treat symptomatically with follow-up as needed.

Initial Tests (lab, imaging)

Testing is usually for GAS, as clinical features do not reliably discriminate between GAS and viral etiologies. Options include:
- Rapid antigen detection test (RADT); quick adjunct to throat culture with 96% specificity and 86% sensitivity (1)[A]
  - Not needed for individuals scoring as low-risk with validated clinical decision-making tool
- Blood agar throat culture; gold standard (90–95% sensitivity) (1)[A]
  - Not needed for adults with negative RADT but recommended for children with negative RADT due to the higher likelihood of complications
- Antistreptolysin O is not recommended for diagnosis.
Other tests if history suggests a different diagnosis:
- NAAT (N. gonorrhoeae)
- Viral cultures (HSV)
- Monospot (EBV)
- IgM serology (CMV)
- HIV viral load
Imaging may be indicated if sequelae of pharyngitis such as retropharyngeal abscess are suspected.

Follow-Up Tests & Special Considerations

Assess for signs of severe infection, such as muffled voice, stridor, or respiratory distress as this may indicate impending airway compromise requiring immediate stabilization or transfer to higher level of care.
Recurrent GAS infection may indicate β-lactamase production by host and may require anti-β-lactamase therapy.

Test Interpretation

Bacitracin disk sensitivity of hemolytic colonies suggests GAS

Treatment

Treatment is aimed at symptomatic relief, unless bacterial infection is suspected or confirmed.

General Measures

Conservative therapy recommended for viral cases:

Salt water gargles
Acetaminophen 10 to 15 mg/kg/dose q4h PRN (pediatric); in adults, do not exceed >4 g/day
Nonsteroidal anti-inflammatory drugs (NSAIDs) are more effective than acetaminophen for GAS pharyngitis.
Although not generally recommended, a single dose of steroids may hasten pain relief for patients aged >5 years.
Anesthetic lozenges
Cool-mist humidifier
Hydration (PO or IV if PO is not tolerated)
Viscous lidocaine (2%) 5 to 10 mL PO q4h swish/spit (severe pain)

Pediatric Considerations
Lower threshold to start antibiotics given higher risk of rheumatic fever

Medication

Antibiotics are used primarily to prevent complications of GAS.
- 60–70% primary care visits by children with pharyngitis result in antibiotic prescriptions, contributing to antibiotic overuse (2)
- Antibiotics minimally reduce risk of poststreptococcal glomerulonephritis
- Antibiotics shorten symptom duration by ~16 hours.
- Antibiotics may prevent pharyngitis/fever by day 3 (NNT 4 if GAS-positive, 6.5 if GAS-negative, 14.4 if untested).
Corticosteroids, when used with antibiotics, may provide a small reduction in the duration of symptoms (24 hours); routine use is not currently recommended (1)[B]

First Line

Recommended first-line antibiotic therapies for GAS include:

Penicillin V: children (<27 kg): 250 mg PO TID (BID dosing sufficient if compliant); adolescents and adults (>27 kg): 250 mg PO QID or 500 mg PO BID for 10 days
Penicillin G benzathine: children <60 lb (27 kg): 600,000 units IM 1 dose; children ≥60 lb and adults: 1.2 million units IM 1 dose
Amoxicillin: 50 mg/kg PO once daily (max 1,000 mg/dose) or 25 mg/kg PO BID (max = 500 mg/dose) for 10 days
- Use with caution if unclear diagnosis as using amoxicillin with EBV infection may induce rash.
In patients who need oral liquids, oral amoxicillin is usually preferred over penicillin.

Second Line

If type IV hypersensitivity without anaphylactic penicillin allergy:
- Cephalexin 20 mg/kg PO BID or (children) 25 to 50 mg/kg/day divided BID or (adults) 1,000 mg PO QID (max = 4 g/day) for 10 days
- Cefadroxil 30 mg/kg PO once daily (max = 1 g/day) for 10 days
If history of anaphylactic penicillin allergy (type I hypersensitivity):
- Azithromycin 12 mg/kg PO once daily (max = 500 mg/dose), then 6 mg/kg (max = 250 mg/dose) once daily for 4 days after
- Clarithromycin 7.5 mg/kg PO BID (max = 250 mg/dose) or (adults) 250 to 500 mg PO BID for 10 days
- Clindamycin 7 mg/kg PO TID (max = 300 mg/dose) or (children) 10 to 30 mg/kg/day PO divided TID–QID or (adults) 150 to 450 mg PO TID–QID for 10 days
Penicillin is most commonly used to prevent rheumatic sequelae; cephalosporins have a lower rate of failure for streptococcal pharyngitis.
For children with lab-confirmed recurrence of GAS pharyngitis, treatment can include a previously used agent.

Issues for Referral

Document GAS-confirmed episodes to support need for future tonsillectomy/adenoidectomy.
Tonsillectomy is recommended for those who have had ≥7 throat infections in 1 year, ≥5 infections/year for the past 2 years, or ≥3 infections/year for the past 3 years
- Tonsillectomy is also recommended in patients who are difficult to treat medically, such as those with allergies to many antibiotics or history of peritonsillar abscess.

Ongoing Care

Follow-up Recommendations

Follow-up culture is not recommended.
If symptoms worsen or persist >5 days, consider peritonsillar abscess.

Diet

As tolerated; ice, tea, soups, and honey may be used for symptom relief with adequate fluid intake.

Prognosis

Acute viral and bacterial infections are typically self-limited to 5 to 7 days.
- GAS symptoms resolve without treatment, but rheumatic complications are still possible.
Treatment failures (symptoms >10 days) may be due to antibiotic resistance, poor compliance, or untreated contacts.
- Without confounding factors, prolonged symptoms should prompt workup for alternative cause.

Complications

Rheumatic fever (e.g., carditis, valve disease, arthritis)
Poststreptococcal glomerulonephritis
Peritonsillar abscess: considered a clinical diagnosis and does not warrant imaging
- Generally requires percutaneous/transoral drainage
- Treatment may involve tonsillectomy, but most sources recommend resolution of infection before surgery.
Acute airway compromise can often be bypassed with nasal trumpets; consult anesthesiologist/otolaryngologist.
Repeated positive GAS tests may represent a chronic carrier of GAS. Antibiotics to treat GAS carriage is not recommended as risk of complications and transmission is low.

Authors

Munima Nasir, MD, FAAFP
Makayla B. Lagerman, MD

References

Sauve L, Forrester AM, Top KA. Group A streptococcal pharyngitis: a practical guide to diagnosis and treatment. Paediatr Child Health. 2021;26(5):319–320. [PMID:34336062]
Hamilton JL, Mccrea L. Streptococcal pharyngitis: rapid evidence review. Am Fam Physician. 2024; 109(4):343–349. [PMID:38648833]

Additional Reading

Miller JM, Binnicker MJ, Campbell S, et al. Guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2024 update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). Clin Infect Dis. 2024:ciae104. doi:10.1093/cid/ciae104. [PMID:38442248]

Codes

ICD-10

J31.1 Chronic nasopharyngitis
A54.5 Gonococcal pharyngitis
B08.5 Enteroviral vesicular pharyngitis
A56.4 Chlamydial infection of pharynx
J02.9 Acute pharyngitis, unspecified
J02 Acute pharyngitis
J31 Chronic rhinitis, nasopharyngitis and pharyngitis
A50.03 Early congenital syphilitic pharyngitis
J02.0 Streptococcal pharyngitis
J31.2 Chronic pharyngitis
J02.8 Acute pharyngitis due to other specified organisms

SNOMED

232403001 Chlamydial pharyngitis
195660001 Acute staphylococcal pharyngitis
195658003 Acute bacterial pharyngitis
312422001 Infective pharyngitis
363746003 Acute pharyngitis
405737000 Pharyngitis
195663004 Allergic pharyngitis
1532007 Viral pharyngitis
140004 Chronic pharyngitis
39271004 Ulcerative pharyngitis
78430008 Adenoviral pharyngitis
74372003 Gonorrhea of pharynx
43878008 Streptococcal sore throat
58031004 Suppurative pharyngitis
232402006 Meningococcal pharyngitis
195662009 Acute viral pharyngitis
195924009 Influenza with pharyngitis
195780008 Pharyngitis sicca
195782000 Chronic follicular pharyngitis

Clinical Pearls

Most cases of pharyngitis are viral and do not require antibiotics.
The risk associated with undiagnosed and untreated GAS is rheumatic sequelae.
The Modified Centor score helps guide testing and treatment.
Penicillin is the preferred first-line therapy for GAS infection, children may prefer amoxicillin for adherence.

Last Updated: 2027