Common Cold & Upper Respiratory Tract Infection (URI): Symptoms, Diagnosis, Red Flags, Treatment Guide, and When to Use Antibiotics

📌 1. Clinical Presentation

Symptom	Typical Findings
Fever	May or may not be present; usually low-grade (<38.3°C)
Cough	Dry or productive
Sore throat	May or may not occur
Nasal symptoms	Rhinorrhea (runny nose), nasal congestion — may be absent
Sputum color	Can be clear/yellow/green → NOT always a bacterial cause
Tonsils	Normal size, no exudate, mild pharyngeal injection
Extra findings	Aphthous-like ulcers in the oropharynx (especially in viral cases)

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🩺 2. History Taking (Mnemonic: DODCRAFTS → for non-pain URI complaints)

Primary History (DODCRAFTS)

• D: “I feel tired, runny nose, nasal congestion.”

• O: Onset? — When did it begin?

• D: Duration — How long so far?

• C: Constant or intermittent?

• R: Not relevant in URI

• A: Associated symptoms — fever? chills? myalgia?

• F: What worsens or improves it? (cold air, lying down, etc.)

• T: Worse at night/morning?

• S: Severity? Mild/moderate?
  

Transition to System Review (THEN FR CS PUB SAW ID)

• T: Travel/contact with sick person?

• H: Headache?

• E: Edema/myalgia?

• N: Nausea, fever, chills?

• F: Racing heart/fever?

• R: Rash/cough/sputum?

• C: Chest pain/SOB?

• S: Sleep?

• P: Pain in joints?

• U: Urinary problems?

• B: Bowel issues?

• S: Sleep?

• A: Appetite?

• W: Weight changes?

• I: Immunization (flu, COVID)?

• D: Dizziness?
  

Key Red Flags:

• Fever > 3 days

• Purulent nasal discharge > 10 days

• Tonsillar exudate + tender cervical nodes
  

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🧑‍⚕️ 3. Physical Examination (HEENT Focused)

Exam Area	Findings
General	Afebrile or low-grade fever
Tonsils	Normal size, no exudate
Pharynx	Mild pharyngeal injection
Cervical LN	No palpable lymph nodes
Nose	May have clear/mucoid discharge
Lung	Clear breath sounds, no crepitation/wheeze

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🔬 4. Lab Investigations

• Usually not needed in typical URI

• Consider only if prolonged/atypical/red flag symptoms:

  • CBC: Mild lymphocytosis → suggest viral

  • CRP: Usually low in viral URI

  • COVID Ag test if relevant

  • ❌ Do not send dengue/lepto/scrub tests on day 1 unless risk factors

  • Strep test: ONLY if tonsillar exudate, fever, tender cervical LN (Centor ≥3)
    

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💊 5. Symptomatic Treatment Options

Drug/Class	Indication	Dose and Notes
Paracetamol	Fever, myalgia	500 mg PO q6h PRN
Chlorpheniramine/Diphenhydramine	Rhinorrhea, congestion	CPM 4 mg q6h PRN or Diphenhydramine 25 mg q8h PRN
Saline Nasal Spray	Nasal moisture, drainage	As needed; no rebound congestion
Dextromethorphan	Dry cough	10–20 mg PO q6–8h PRN — Avoid if productive cough
Ambroxol (preferred)	Productive cough	30 mg PO tid; better mucokinetic effect
Bromhexine	Alternative mucolytic	8–16 mg PO tid

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🚫 6. When NOT to Use Antibiotics

Feature	Interpretation
Sore throat without exudate	Suggests viral
Nasal discharge <10 days	Likely viral
Low CRP, no red flags	Viral
No Centor ≥3	No strep

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✅ 7. When to Consider Antibiotics (per Thai CPG)

Indication	Reason/Diagnosis
Fever > 3 days	May suggest bacterial superinfection
Purulent nasal discharge > 10 days	Likely bacterial sinusitis
Tonsillar exudate + tender cervical LN	Streptococcal pharyngitis
Positive rapid strep test	Confirmed strep
Centor Score ≥3	Predicts higher chance of strep

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📋 Modified Centor Criteria:

Criteria	Score
Tonsillar exudate	+1
Tender anterior cervical nodes	+1
Fever >38°C	+1
Absence of cough	+1
Age 3–14	+1
Age 15–44	0
Age ≥45	–1

• 0–1 pts: No testing/antibiotic

• 2–3 pts: Consider test or culture

• ≥3 pts: Empiric antibiotics or test-and-treat
  

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💊 8. Antibiotic Options (if Indicated)

Drug	Dose
Amoxicillin	50 mg/kg/day ÷ q8–12h (Max: 500 mg q8h)
Amoxiclav (if failure/recurrent)	500/125 mg q8h or 875/125 mg q12h for 5–10 days

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🗣️ 9. Patient Advice

• Hydrate well

• Rest and avoid dust/smoke/cold air

• Reassess if:

  • Symptoms worsen

  • Persist >7–10 days

  • Fever >3 days
    

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🔚 Summary Decision Tree

Clinical Picture	Antibiotics?	Reason
Viral URI, <7 days, clear discharge	❌ No	Self-limited, viral
Purulent nasal discharge >10d, facial pain	✅ Yes	Bacterial sinusitis
Tonsillar exudate + tender anterior LN + fever	✅ Yes	Likely strep pharyngitis
Centor <2	❌ No	Low risk