Common Cold & Upper Respiratory Tract Infection (URI): Symptoms, Diagnosis, Red Flags, Treatment Guide, and When to Use Antibiotics
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📌 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) |
🩺 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
🧑⚕️ 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 |
🔬 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)
💊 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 |
🚫 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 |
✅ 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 |
📋 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
💊 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 |
🗣️ 9. Patient Advice
- Hydrate well
- Rest and avoid dust/smoke/cold air
- Reassess if:
- Symptoms worsen
- Persist >7–10 days
- Fever >3 days
🔚 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 |
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