The common cold is a self-limiting illness that is well known around the world. Many individuals will experience at least one cold per year, particularly in the fall and spring seasons. The symptoms and treatments of the common cold are often familiar. However, their underlying mechanisms of action might still remain a mystery to some people.
Cold Viruses
The common cold is an upper respiratory tract infection caused by a virus. The most common virus behind the cold is the rhinovirus, of which over 100 serotypes exist. The cold is also due to other types of viruses, such as coronavirus, adenovirus, and the influenza virus.
The cold virus is spread through aerosol droplets that enter the upper respiratory tract by direct contact or inhalation and make contact with the epithelial lining. This stimulates a response by the immune system, part of which involves widening of the local blood vessels and increased fluid secretion by glands underneath the respiratory epithelium. This pathophysiologic process produces the symptoms of the common cold.
Cold Symptoms
Individuals who suffer from a cold first experience a sore throat approximately one to three days after inoculation of the virus. From there, symptoms over the next few days include running nose (rhinorrhea), nasal congestion, and sneezing. Nasal secretions are initially thin fluid before they have an increased mucus content. Malaise is often another associated symptom, but fever is frequently absent in the common cold.
The cold itself is not a major illness but may be a cofactor for other illnesses. For example, patients with asthma or bronchitis may experience worsening of these conditions in response to a cold. Also, the cold may predispose one to bacterial infections such as sinusitis and middle ear infections (otitis media).
Cold Treatments
The treatment of the common cold does not target the causative virus. Instead, it addresses the symptoms while the immune system works to eliminate the cold virus. Medications for cold symptoms include antihistamines such as oral Benadryl and anticholinergic agents such as Atrovent nasal spray. These agents work by inhibiting nasal secretions. Nonsteroidal anti-inflammatory drugs (NSAIDs) are useful if fever and pain are present, and antibiotics can address concurrent bacterial infections.
Various remedies, such as zinc, vitamin C, and Echinacea, have been promoted as treatments for the common cold, but studies to date have not demonstrated significant benefit. However, handwashing and proper hygiene can prevent the spread of the cold to others.
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