Common Cold
The common cold is a mild, self-limited viral upper respiratory infection and the single most frequent reason people miss work or school.
Symptoms
Runny nose, congestion, sneezing, mild sore throat, and cough, usually without the high fever or severe body aches of flu.
Causes and risk
Rhinovirus is the most common culprit among 200-plus possible viruses. Close contact, season, and young children in the household all raise exposure risk.
How it is evaluated
Colds are distinguished from flu and COVID by symptom pattern -- gradual onset, lower fever prominence, less body ache -- though overlap is real enough that testing is the only reliable way to tell flu and COVID apart when it matters clinically.
Treatment
Symptomatic care -- fluids, rest, saline rinses, analgesics -- is the mainstay. ACP/CDC high-value care guidance recommends against antibiotics, which have no role in preventing sinusitis, ear infections, or asthma flares from a cold. Cochrane evidence does not support vitamin C, echinacea, intranasal steroids, or heated humidified air for uncomplicated colds; combination antihistamine-decongestant-analgesic products and zinc taken within 24 hours have modest supporting evidence. Cough and cold medicines should be avoided in children under 4, and aspirin should never be given to children with a viral illness.
When to seek care
Symptoms lasting beyond 10 days, worsening after initial improvement ("double sickening"), high fever, or difficulty breathing warrant a visit rather than continued home care.