Conditions · Infectious and tropical diseases
Common cold (acute viral rhinopharyngitis) !
The common cold is a mild viral infection of the nose and throat. It clears by itself in about a week, and antibiotics do not help.
Updated 2026-11-01
Structures involved
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Microorganisms that cause it
Why it happens
- Histamine, serotonin, bradykinin and the plasma protein cascades
- Airway defenses, cough and mucociliary clearance
- The airway: from nose to bronchioles
What it is
A self-limited viral infection of the upper airway, mainly the nasal mucosa and pharynx, causing runny or blocked nose, sneezing, sore throat and mild cough. It is the most frequent infection in humans.
Who gets it
Adults have a few colds a year and young children several more, especially in day care. In Colombia and other tropical countries colds occur all year, with peaks in the rainy seasons. Colds and other acute respiratory infections are a leading reason for primary-care visits and for unnecessary antibiotic prescribing.
Causes
- Rhinoviruses, the most common cause
- Seasonal human coronaviruses, parainfluenza viruses, adenoviruses, enteroviruses, respiratory syncytial virus and human metapneumovirus
- Spread by droplets, by hand contact with secretions and contaminated surfaces, then self-inoculation of the nose or eyes
Risk factors
- Young age and attendance at day care or school
- Close contact with children or crowded living spaces
- Smoking and exposure to tobacco smoke
- Psychological stress and poor sleep
- Asthma or chronic lung disease (more severe course, not more colds)
Pathophysiology
The virus infects the epithelium of the nose and nasopharynx, often with little cell destruction. Inflammatory mediators such as bradykinin and cytokines dilate vessels and increase mucus secretion, which causes congestion, rhinorrhoea and sore throat. Swollen mucosa can block the sinus ostia and Eustachian tube, which is why colds often precede sinusitis and otitis media.
Symptoms and signs
- Sore or scratchy throat, often the first symptom
- Sneezing, runny nose and nasal blockage; discharge may turn thick, yellow or green without meaning bacterial infection
- Cough, which can persist for one to two weeks or more
- Mild headache, malaise and body aches
- Low or no fever in adults; fever is more common in young children
Diagnosis
- Clinical
- Diagnosed from the typical history and examination: nasal congestion and rhinorrhoea with a red, mildly sore pharynx, clear chest and no signs of severe illness.
- Tests
- Usually none. Testing for influenza or SARS-CoV-2 is considered when those are circulating or the person is at high risk, because specific antivirals exist for them. A rapid streptococcal test is reserved for sore throat with features of bacterial pharyngitis.
- Imaging
- Not needed. A chest X-ray is only for suspected pneumonia.
Differential diagnosis
- Influenza (abrupt high fever, myalgia, prostration)
- COVID-19
- Allergic rhinitis (itching, sneezing, seasonal pattern, no fever)
- Acute bacterial sinusitis
- Streptococcal pharyngitis (fever, tonsillar exudate, tender neck nodes, no cough)
- Foreign body in the nose (one-sided foul discharge in a child)
Goal of treatment
Relieve symptoms while the infection clears on its own, avoid unnecessary antibiotics and recognise complications or other infections early.
Treatment
- Conservative
- Rest, adequate fluids, saline nasal irrigation or drops, honey for cough in children over one year, and handwashing to limit spread.
- Medical
- Symptomatic drugs such as analgesic-antipyretics (paracetamol, NSAIDs) and, in adults, short courses of topical decongestants. Antibiotics have no effect on the cold, and aspirin is avoided in children and adolescents because of Reye syndrome.
- Follow-up
- Watch for breathing difficulty, dehydration, high fever or prolonged symptoms, particularly in infants, older adults and people with asthma or COPD.
Complications
- Acute otitis media, especially in children
- Acute bacterial sinusitis
- Asthma or COPD exacerbation
- Lower respiratory infection such as bronchitis, bronchiolitis or pneumonia
- Adverse effects and resistance from unnecessary antibiotics
Prognosis
Excellent. Most symptoms improve within a week, though cough can last longer. Repeated colds are expected because many different viruses cause them and immunity is short-lived.
Prevention
- Handwashing and covering coughs and sneezes
- Staying home while sick and cleaning shared surfaces
- No vaccine exists for the cold itself; influenza and COVID-19 vaccines prevent illnesses that resemble it
Test yourself
Think of the answer, then tap the question to see it.
Which virus is the most common cause of the common cold?
Rhinovirus.
Does green or yellow nasal discharge in a cold mean a bacterial infection needing antibiotics?
No. Coloured discharge is common in viral colds; antibiotics do not help and add harm.
Which ear complication most often follows a cold in young children?
Acute otitis media, from Eustachian tube blockage by swollen mucosa.
Why is aspirin avoided for colds in children and adolescents?
Because of the risk of Reye syndrome (acute liver failure and encephalopathy) after viral infections.
Related conditions
- Influenza (flu)
- COVID-19
- Allergic rhinitis
- Acute rhinosinusitis
- Acute otitis media
- Streptococcal pharyngitis
- Acute bronchitis
- Bronchiolitis (RSV)
- Asthma
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Common Cold | Viral Infection | MedlinePlus (MedlinePlus (U.S. National Library of Medicine), 2024); About Common Cold | Common Cold | CDC (Centers for Disease Control and Prevention, 2024).
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