What are the signs and symptoms of pneumonia?

Signs and Symptoms of Pneumonia

Pneumonia should be suspected when a patient presents with cough or difficulty breathing accompanied by fever, tachypnea, and abnormal lung sounds such as crackles or diminished breath sounds. 1, 2

Respiratory Symptoms

• Cough is the cardinal respiratory symptom, either new onset or increased from baseline 1, 3
• Dyspnea (difficulty breathing) or breathlessness significantly increases pneumonia likelihood 1, 2
• Pleuritic chest pain (sharp pain worsening with breathing) is a key symptom to evaluate 1, 4

Systemic Signs

• Fever ≥38°C with chills and sweats are important clinical signs 1, 3
• Tachycardia commonly accompanies pneumonia but has low specificity 5
• Fatigue and malaise are frequent presenting features 4, 6
• Loss of appetite is a common systemic manifestation 4

Vital Sign Abnormalities

• Tachypnea (respiratory rate >24/min in adults, age-adjusted thresholds in children) is a critical sign 1, 2
• Hypoxemia (SpO₂ <93% or altitude-adjusted) indicates severity 5

Physical Examination Findings

• Inspiratory crackles are the most diagnostically significant breath sound, present in approximately 81% of pneumonia patients 2
• Diminished breath sounds in affected lung regions due to consolidation 2
• Rhonchi may be present but are less specific 2
• Absence of rhinorrhea (runny nose) significantly increases pneumonia probability 1, 2

Severe Pneumonia Warning Signs

In severe cases, look for WHO-defined general danger signs 5:

• Inability to drink or vomiting everything
• Convulsions
• Lethargy or unconsciousness
• Severe respiratory distress signs: head nodding, persistent nasal flaring, grunting, stridor while calm, tracheal tugging, intercostal retractions, pronounced lower chest wall indrawing 5

Laboratory Markers

• C-reactive protein (CRP) >30 mg/L strongly increases pneumonia probability when symptoms and signs are present 1, 2
• Leukocytosis (WBC >10,000/μL) or leukopenia (WBC <4,000/μL) support the diagnosis 7, 3
• CRP <10 mg/L in the absence of dyspnea and daily fever makes pneumonia less likely 1, 2

Age-Specific Presentations

Important caveat: Children and elderly patients often present atypically 4, 8:

• Children may present with headache, nausea, abdominal pain, or absence of typical symptoms 4
• Elderly patients may have acute functional or cognitive decline without classic respiratory symptoms 8

Clinical Decision Algorithm

1. Start with respiratory symptoms: If cough OR difficulty breathing is present, proceed to assess clinical signs 5
2. Assess vital signs: Check for tachypnea, fever, and hypoxemia 1, 2
3. Perform lung examination: Listen for crackles, diminished breath sounds, or rhonchi 2
4. Consider CRP measurement: When diagnosis is uncertain, CRP >30 mg/L strengthens diagnosis 1, 2
5. Obtain chest imaging: Radiography should confirm consolidation or infiltrates when clinical findings suggest pneumonia 1, 2

Common Pitfalls

• Fever and tachycardia alone have low specificity and should not drive diagnosis without respiratory findings 5
• Wheezing, cough, or rhonchi alone do not significantly increase pneumonia likelihood on chest radiograph 2
• Normal vital signs with normal lung examination make pneumonia unlikely and do not warrant routine antibiotics 2
• Elderly patients may lack fever despite radiographic pneumonia 2