Common Cold (Acute Nasopharyngitis) ไข้หวัด

• ICD-10:
  • J00 – Acute nasopharyngitis (common cold)
  • J06.9 – Acute upper respiratory infection, unspecified
• ICD-11 (MMS 2025-01):
  • CA00 – Acute nasopharyngitis (common cold)
  • CA00.0 – Acute coryza
  • CA00.1 – Rhinopharyngitis
  • CA00.Y – Other specified acute nasopharyngitis
  • CA00.Z – Acute nasopharyngitis, unspecified

Overview

The common cold, or acute nasopharyngitis, is a mild, self-limiting viral infection of the upper respiratory tract (URT), affecting the nasal mucosa, pharynx, and occasionally the lower airways. It is one of the leading causes of absenteeism from work and school, with adults experiencing 2–4 episodes and children up to 8–12 episodes annually.

Clinically, the disease manifests with nasal congestion, rhinorrhoea, sore throat, cough, sneezing, and malaise, often without high-grade fever. Symptoms peak within 2–3 days and resolve spontaneously. Though benign, the common cold imposes a significant socioeconomic burden due to its high prevalence.

Epidemiology

The common cold is ubiquitous and affects individuals of all ages worldwide. Incidence is highest in children under 6 years and declines with age due to the gradual development of adaptive immunity. Seasonal peaks occur in temperate climates during autumn and winter and in tropical regions during the rainy season. Rhinoviruses account for 30–50% of cases, with over 150 known serotypes, making lasting immunity difficult.

Risk factors include young age, exposure to crowded environments (e.g. schools, daycare centres), poor hand hygiene, smoking, allergic rhinitis, and immunocompromised states.

Microbiology

Pathophysiology

Systemic symptoms such as fatigue and malaise are mediated by cytokine-induced systemic inflammation. Viral shedding peaks in the first 2–3 days and declines thereafter, though PCR may detect viral RNA for several weeks post-symptom resolution.

Clinical Presentation

Sign & Symptom	Pathogenesis	Frequency	Specificity
Nasal congestion / rhinorrhoea	Mucosal inflammation, vasodilation, mucus hypersecretion	++++	++
Sore throat / pharyngitis	Mucosal irritation and inflammation	+++	++
Sneezing	Stimulation of trigeminal sensory fibres	++++	+
Cough (dry or mild productive)	Postnasal drip, airway irritation	+++	+
Low-grade fever, malaise	Systemic cytokine release	++	+

Investigation

The diagnosis of common cold is clinical. Laboratory testing is not routinely required except in atypical or severe cases.

• General findings: Normal WBC count or mild lymphocytosis.
• CRP/ESR: Typically normal or minimally elevated.
• Virology: PCR or rapid antigen tests can identify viral pathogens (mainly in research or outbreak settings).
• Imaging: Not indicated unless complications suspected (e.g. sinusitis, pneumonia).

Diagnosis Criteria (Dx)

The diagnosis is made clinically based on the following features:

• Sudden onset of nasal congestion, rhinorrhoea, sneezing, and sore throat.
• Mild, self-limited symptoms lasting ≤10 days.
• Absence of high fever, purulent nasal discharge, or severe systemic symptoms (which suggest influenza or bacterial infection).

Laboratory or imaging studies are unnecessary in uncomplicated cases. Differential diagnosis should be considered when symptoms persist beyond 10–14 days, worsen after initial improvement, or present with focal findings.

Differential Diagnosis (DDx)

Disease	Distinguishing Features	Laboratory Findings	Specific Test
Influenza	Sudden high fever, myalgia, headache, severe fatigue	Leukopenia, ↑ CRP	Rapid influenza antigen / PCR
COVID-19	Loss of taste/smell, prolonged fever, cough, fatigue	Variable; may show lymphopenia	RT-PCR for SARS-CoV-2
Allergic rhinitis	Itchy eyes/nose, sneezing fits, seasonal pattern	Eosinophilia on nasal smear	Skin prick / IgE test
Acute sinusitis	Facial pain, purulent nasal discharge, symptoms >10 days	↑ ESR/CRP occasionally	Sinus X-ray / CT if complicated
Group A streptococcal pharyngitis	Sudden sore throat, tonsillar exudate, absence of cough	Leukocytosis	Rapid antigen detection test, throat culture

Treatment Overview

The treatment of the common cold is primarily supportive, aiming to relieve symptoms and improve patient comfort while the body’s immune system clears the infection. Because the disease is viral, antibiotics are not indicated unless secondary bacterial infection is suspected.

The mainstays of therapy include adequate hydration, rest, antipyretics, and symptomatic medications for nasal congestion, cough, or sore throat. Pharmacologic and non-pharmacologic approaches may be combined to optimise patient recovery and prevent complications such as sinusitis or otitis media.

• Rest and hydration: Maintain fluid intake to prevent dehydration and thin mucus secretions.
• Antipyretics/analgesics: Paracetamol or NSAIDs relieve headache, myalgia, and fever.
• Decongestants: Provide temporary relief of nasal obstruction.
• Antitussives/expectorants: For troublesome cough only; otherwise, limited evidence of benefit.
• Saline irrigation or steam inhalation: Improves nasal patency and reduces mucosal dryness.

Pharmacology

Pharmacologic treatment of the common cold is symptomatic and targeted at the most bothersome symptoms. There are no agents that shorten the duration of illness substantially, but certain medications can improve quality of life during the symptomatic period.

1. Antipyretics and Analgesics

Paracetamol (acetaminophen) remains the first-line agent for fever, sore throat, and headache. It acts centrally by inhibiting prostaglandin synthesis in the hypothalamus. The standard dose for adults is 500–1000 mg every 6 hours (maximum 4 g/day). In children, 10–15 mg/kg per dose every 4–6 hours is recommended.

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (400 mg every 6–8 hours) are alternatives with anti-inflammatory effects but should be avoided in patients with gastritis, renal impairment, or peptic ulcer.

2. Decongestants

Topical nasal decongestants (e.g., oxymetazoline 0.05% nasal spray, 1–2 sprays per nostril every 8–12 hours) act via α-adrenergic agonism causing vasoconstriction and reduced mucosal swelling. They provide rapid relief but should not be used for more than 5 consecutive days due to the risk of rebound congestion (rhinitis medicamentosa).

Oral decongestants such as pseudoephedrine (60 mg every 6 hours) or phenylephrine (10 mg every 6 hours) improve nasal airflow but may cause insomnia, hypertension, or tachycardia, and are contraindicated in patients with cardiovascular disease or uncontrolled hypertension.

3. Antihistamines

First-generation antihistamines (e.g., chlorpheniramine 4 mg every 6 hours, diphenhydramine 25 mg every 6 hours) are sometimes used in combination with decongestants to reduce rhinorrhoea and sneezing. Their benefit is modest and due mainly to anticholinergic drying effects rather than histamine blockade. Sedation and impaired psychomotor function are common adverse effects, making them unsuitable for drivers or machine operators.

Second-generation antihistamines (cetirizine, loratadine, fexofenadine) have minimal sedative properties but are less effective for cold symptoms.

4. Cough Remedies

Cough in the common cold is usually due to postnasal drip rather than lower respiratory involvement. Antitussives such as dextromethorphan (10–20 mg every 6 hours) suppress the cough reflex and may be helpful in dry, non-productive cough. Expectorants like guaifenesin (200–400 mg every 6 hours) are used to loosen mucus, though evidence of efficacy is limited.

5. Mucolytics

Agents such as acetylcysteine (200 mg three times daily) may aid in mucus clearance but are not routinely required in uncomplicated colds.

6. Intranasal Corticosteroids

Corticosteroid sprays (fluticasone, mometasone) have limited utility in the common cold but can be beneficial in patients with concurrent allergic rhinitis. They act by reducing mucosal inflammation and nasal blockage.

7. Zinc and Vitamin C

Evidence for zinc lozenges (≥75 mg elemental zinc/day) suggests a potential to shorten symptom duration if initiated within 24 hours of onset, but gastrointestinal upset and metallic taste are common. Vitamin C prophylaxis may reduce cold incidence in physically stressed populations (e.g., athletes) but not in the general population.

8. Herbal and Alternative Remedies

Echinacea, ginseng, and honey-based preparations have been studied but results are inconsistent. Honey (1–2 teaspoons at bedtime) may reduce nocturnal cough in children >1 year (avoid in infants due to botulism risk).

Summary Table

Drug Class	Example	Mechanism	Typical Adult Dose	Comments
Antipyretic	Paracetamol	Central COX inhibition	500–1000 mg q6h	First-line for pain and fever
NSAID	Ibuprofen	Peripheral COX inhibition	400 mg q8h	Alternative; avoid in renal disease
Decongestant (topical)	Oxymetazoline spray	α-adrenergic agonist	1–2 sprays q12h	Use ≤5 days to avoid rebound
Antihistamine	Chlorpheniramine	H1 receptor antagonist	4 mg q6h	Causes sedation
Antitussive	Dextromethorphan	Cough reflex suppression (medulla)	10–20 mg q6h	For dry cough only
Expectorant	Guaifenesin	Increase airway secretion	200–400 mg q6h	Hydration improves effect

No antiviral drugs are indicated for routine common cold management. Antibacterial therapy is reserved only when secondary bacterial infection develops. The rational use of symptomatic medications, avoidance of polypharmacy, and patient education remain the cornerstone of care.

Treatment Guideline

Management follows international consensus and national guidelines, focusing on supportive care and patient education.

• Step 1: Confirm viral nature by absence of bacterial red flags (fever >38.5°C, purulent sputum, unilateral sinus pain).
• Step 2: Advise rest, hydration, and non-pharmacologic measures (saline nasal irrigation, steam inhalation).
• Step 3: Provide symptomatic treatment:
  • Paracetamol or ibuprofen for pain and fever
  • Topical or oral decongestant for nasal blockage
  • Honey, throat lozenges, or antitussive for cough
• Step 4: Avoid unnecessary antibiotics; re-evaluate after 7–10 days if symptoms persist or worsen.
• Step 5: Educate on hygiene, cough etiquette, and avoidance of spreading infection.

Example Doctor’s Orders

Prognosis

The common cold is a self-limiting illness with an excellent prognosis. Most cases resolve spontaneously within 7–10 days. Cough may persist up to 2–3 weeks due to postnasal drip.

Complications are uncommon and include acute sinusitis, otitis media (especially in children), and lower respiratory tract infection in elderly or immunocompromised patients.

Prevention

• Frequent handwashing with soap and water for at least 20 seconds.
• Avoid touching the face, eyes, and mouth with unwashed hands.
• Use alcohol-based hand sanitisers when washing is unavailable.
• Cover mouth and nose with tissue or elbow when coughing or sneezing.
• Disinfect commonly touched surfaces and maintain good ventilation.
• Maintain adequate sleep, nutrition, and exercise to boost immunity.

Conclusion

Quiz (USMLE / OSCE)

Frequently Asked Questions (FAQ)

Q1: Do antibiotics help in the common cold?

A: No. The common cold is viral, and antibiotics have no role unless bacterial superinfection is suspected.

Q2: Can vitamin C or zinc prevent colds?

A: Routine vitamin C does not prevent colds but may slightly reduce duration. Zinc lozenges may help if taken early but can cause nausea or metallic taste.

Q3: Are children more susceptible?

A: Yes. Children have immature immunity and frequent exposure in schools, leading to more episodes per year than adults.

Q4: How to differentiate between influenza and the common cold?

A: Influenza has abrupt onset, high fever, and severe myalgia; the common cold is milder and gradual.

Q5: When should I seek medical attention?

A: If symptoms persist beyond 10 days, worsen after initial improvement, or are associated with high fever, dyspnoea, or purulent discharge.