What is the differential diagnosis and initial management for a patient presenting with a scratchy throat?

Differential Diagnosis for Scratchy Throat

A scratchy throat is most commonly caused by viral upper respiratory infections (rhinovirus, coronavirus, adenovirus, influenza, parainfluenza, RSV), followed by allergic rhinitis with postnasal drainage, and less commonly by Group A β-hemolytic streptococcal (GABHS) pharyngitis—which is the only bacterial cause requiring specific antibiotic treatment. 1, 2

Primary Infectious Causes

Viral Etiologies (Most Common)

• Respiratory viruses account for the majority of cases: rhinovirus, coronavirus, adenovirus, influenza, parainfluenza, and respiratory syncytial virus 2
• Epstein-Barr virus (infectious mononucleosis) presents with pharyngitis plus generalized lymphadenopathy and splenomegaly—specifically look for posterior cervical adenopathy 2
• Viral pharyngitis is strongly suggested by: conjunctivitis, cough, hoarseness, coryza (runny nose), diarrhea, anterior stomatitis, discrete ulcerative lesions, or viral exanthem 1, 2
• Herpes simplex virus can cause vesicular lesions in the throat 1
• Coxsackievirus and ECHO viruses may produce characteristic herpangina 1

Bacterial Etiologies

• GABHS accounts for 15-30% of pharyngitis in children and only 5-15% in adults, making it the most common bacterial cause requiring antibiotics 2
• Clinical features suggesting GABHS: sudden-onset sore throat, fever, tonsillar exudates, tender anterior cervical adenopathy, absence of cough, and patient age 5-15 years 1, 2
• Groups C and G β-hemolytic streptococci can cause pharyngitis with milder presentation than GABHS 2
• Mycoplasma pneumoniae and Chlamydia pneumoniae are uncommon causes, often associated with atypical pneumonia 1
• Neisseria gonorrhoeae in sexually active individuals 1
• Arcanobacterium haemolyticum (rare in US, may present with scarlet fever-like rash in teenagers/young adults) 1

Critical Distinction: GABHS Carriers vs. Acute Infection

• Chronic GABHS carriers (10.9% in children ≤14 years, 2.3% in adults 15-44 years) with intercurrent viral infections are difficult to differentiate from acute infection 2
• Carriers show extremely low risk of post-streptococcal complications and low transmission likelihood 2

Non-Infectious Causes

Allergic/Inflammatory

• Allergic rhinitis with postnasal drip presents as scratchy throat with: nasal itching, sneezing, clear rhinorrhea, nasal congestion, and often ocular symptoms (itching, tearing) 1
• Key allergic features: seasonal pattern (outdoor allergens like pollen), perennial symptoms (indoor allergens like dust mites, pet dander, mold), or episodic exposure-associated symptoms 1
• Children may only complain of malaise, fatigue, or cough—must specifically ask about rhinorrhea and nasal/ocular itch 1
• Vasomotor rhinitis (nonallergic) triggered by irritants (smoke, fumes, chemicals, temperature/humidity changes) 1

Gastroesophageal Reflux

• GERD can cause chronic throat irritation and scratchy sensation 2

Environmental/Occupational

• Chronic irritant exposure from smoking, environmental allergens, or occupational exposures 1, 2
• Medication-induced: antihypertensive drugs, psychotropic agents, and topical decongestants may cause nasal/throat symptoms 1

Life-Threatening Conditions to Rule Out

Suppurative Complications

• Peritonsillar abscess (quinsy): severe unilateral throat pain, trismus, uvular deviation, "hot potato voice"—mainly in young adults 2
• Retropharyngeal abscess: requires surgical drainage 3, 4
• Lemierre's syndrome: rare but serious—suppurative thrombophlebitis of internal jugular vein with persistent fever, neck pain, septic emboli 2

Airway Emergencies

• Epiglottitis (Haemophilus influenzae type b): cherry-red epiglottis, requires immediate airway management 3, 4
• Diphtheria: typical membrane present (rare in developed countries) 3

Diagnostic Approach Algorithm

Step 1: Identify Viral Features (No Testing Needed)

If any of these present, viral etiology is most likely—do not test or treat with antibiotics 1, 2:

• Conjunctivitis
• Cough
• Hoarseness
• Coryza (runny nose)
• Diarrhea
• Anterior stomatitis
• Discrete ulcerative lesions
• Viral exanthem

Step 2: Apply Modified Centor Criteria for GABHS Risk

Assign 1 point for each 2, 5:

• Fever (temperature >38°C)
• Absence of cough
• Tonsillar exudates
• Tender anterior cervical lymphadenopathy

Score 0-1: Do NOT test or treat—viral etiology most likely 2
Score 2: Consider testing if high community prevalence or patient preference 2
Score 3-4: Perform rapid antigen detection test (RADT) before prescribing antibiotics 2

Step 3: Assess for Allergic Rhinitis

If scratchy throat accompanied by 1:

• Nasal itching, sneezing, clear rhinorrhea
• Ocular symptoms (itching, tearing)
• Seasonal pattern or specific allergen exposure
• Absence of fever

Diagnosis: Presumptive allergic rhinitis—can be made clinically without testing 1

Step 4: Red Flags Requiring Urgent Evaluation

Immediately investigate if 1, 4:

• Unilateral symptoms (rhinorrhea, nasal blockage)
• Severe headache
• Epistaxis
• Anosmia
• Trismus or uvular deviation
• Respiratory distress or stridor
• Inability to swallow secretions

Initial Management

For Viral Pharyngitis (Most Common)

• Ibuprofen or acetaminophen strongly recommended for symptom relief 2
• Adequate hydration with cool liquids 2
• No antibiotics 2

For Suspected GABHS (Centor Score 3-4 with Positive RADT)

• Penicillin V twice or three times daily for 10 days (first-line) 2
• For penicillin allergy: first-generation cephalosporins, clindamycin, or macrolides 2
• Discuss modest benefits versus side effects, antimicrobial resistance, and costs 2

For Allergic Rhinitis

• Intranasal corticosteroids (most effective for all symptoms including postnasal drip) 1
• Second-generation oral antihistamines (effective for itching, sneezing, rhinorrhea—less effective for congestion) 1
• Allergen avoidance measures targeting identified triggers 1
• Note: Nonsedating oral antihistamines are NOT effective for nonallergic rhinitis 1

For Vasomotor/Nonallergic Rhinitis

• Intranasal corticosteroids or intranasal antihistamines 1
• Intranasal anticholinergics for predominant rhinorrhea 1
• Avoid aggravating irritants 1

Common Pitfalls to Avoid

1. Do NOT prescribe antibiotics for viral pharyngitis (presence of cough, coryza, conjunctivitis, or diarrhea) 1, 2
2. Do NOT treat GABHS carriers with antibiotics unless special circumstances exist (outbreak, family history of rheumatic fever, excessive anxiety) 2
3. Do NOT rely on clinical features alone to diagnose GABHS—microbiological confirmation required 2
4. Do NOT miss life-threatening causes: maintain high suspicion for epiglottitis, peritonsillar abscess, or retropharyngeal abscess in appropriate clinical context 4
5. Do NOT overlook medication-induced causes: review antihypertensives, psychotropic agents, and topical decongestant overuse 1