COMMON COLD IN A NUTSHELL

The common cold is a viral infection of the upper respiratory tract. Common colds can be caused by over 200 distinct viral pathogens, typically from the rhinovirus, influenza virus, and other common virus families. Because there are so many distinct cold-causing viruses, developing immunity against the common cold is unlikely.

Infection occurs when the virus reaches mucous membranes (eg, eyes, nose, mouth), often via direct contact or respiratory droplets from an infected individual. Colds generally resolve without treatment, and conventional treatments are mostly palliative and aim to shorten the duration of the illness and prevent complications such as a secondary bacterial infection. However, no cold medication is yet known to effectively decrease duration, severity, or risk of complications.

Nutrients such as probiotics, vitamin D, and zinc lozenges may help prevent the common cold and aid the body’s immune response.

What are Signs and Symptoms of the Common Cold?

• Nasal swelling and congestion
• Runny nose
• Sore throat
• Coughing and sneezing
• Low-grade fever
• Mild aches

Note: Cold symptoms are usually mild. If symptoms are more severe (eg, high fever, severe body aches, shortness of breath, digestive symptoms), notify a healthcare provider as this may indicate a more serious condition, such as the flu.

What are Ways to Prevent the Common Cold?

• Wash and sanitize hands and surfaces, and avoid touching your eyes, nose, and mouth.
• Gargling with salt water and nasal irrigation may help mechanically remove viruses from mucous membranes.
• Maintain adequate vitamin D levels.
• Humidify air if you are in a low-humidity environment.
• Maintain a healthy lifestyle—avoid smoking, get enough exercise and sleep, and eat a healthy diet such as the Mediterranean diet.

What are Conventional Medical Treatments for the Common Cold?

• DO NOT take antibiotics for a common cold.
• Gargling (eg, with salt water) and nasal irrigation may help improve symptoms and reduce duration of the illness.
• Some over-the-counter medications that may help relieve cold symptoms include:
  • Analgesics
  • Decongestants
  • Antihistamines, and others.

Note: Many cold medicines contain the same active ingredients. ALWAYS read labels to ensure you do not exceed the recommended dose.

What Nutrients May Be Beneficial for the Common Cold?

• Probiotics. Specific probiotics have been shown to reduce incidence and duration of upper respiratory tract infections.
• Beta-glucans. These prebiotic fibers may stimulate the body’s antimicrobial defense and prevent infection as well as decrease symptoms.
• Vitamin D. Regular vitamin D supplementation and maintaining higher vitamin D levels are associated with a decreased risk of seasonal viral infection and acute respiratory infection.
• Zinc. Zinc deficiency has been linked to immune impairment and susceptibility to infection; zinc can bolster the body’s ability to fight off viruses. Using zinc in the form of a lozenge within 24 hours of symptom onset may reduce the duration and severity of a cold.
• Vitamin C. Vitamin C augments several aspects of the immune system and helps defend against infections. Using vitamin C may reduce the chances of catching a cold and cold duration.
• Echinacea. Echinacea may reduce the incidence of colds and sick days, as well as reducing the risk of recurrent infections.

Viral infection triggers the release of a wide array of pro-inflammatory molecules, which are responsible for the well-known symptoms of the common cold. Interferons and cytokines produced by infected cells help inhibit infection spread to nearby cells and initiate the immune response. Leukotrienes, bradykinin, and other peptides released as part of the immune response stimulate mucus secretion, vasodilation, and increased blood vessel permeability that lead to nasal congestion and runny nose. In addition, some of these molecules trigger increased acetylcholine signaling in the nervous system, which can further contribute to mucous production, coughing, and sneezing. Both viral activity and the immune response cause varying degrees of cell damage and disruption to the integrity of the epithelial barrier, leading to increased risk of secondary infections.

Ultimately, the immune response leads to containment of infection, destruction of infected cells, tissue repair, and restoration of homeostasis. In addition, specialized immune cells develop lasting memory that may prevent re-infection by the same virus. Nevertheless, since there are many cold-causing viruses with vast variability in the specific immune response they elicit, recovery from the common cold does not protect against another cold, and many people experience multiple colds in one season.

The following conditions frequently overlap or share symptoms with the common cold, and a small percentage of cases are due to bacterial infections that may respond to antibiotic therapy:

• Acute rhinosinusitis. Swelling of the nasal passages and sinuses, or rhinosinusitis, can occur during or following the common cold. In addition to nasal congestion and discharge, it may be marked by facial pain. Acute rhinosinusitis can be caused by a bacterial infection, but most cases are viral.
• Acute pharyngitis. A sore throat is a characteristic symptom of the common cold, but when it is the predominant symptom, it may indicate simple acute pharyngitis. It is estimated that 70–95% of pharyngitis cases are viral, while the rest are bacterial (eg, strep throat).
• Acute bronchitis. Bronchitis is an inflammation of the trachea and large bronchial passages, but it does not involve the lungs. Acute bronchitis frequently follows a cold and is characterized by a cough that may be accompanied by chest pain, wheezing, shortness of breath, and breath sounds known as crackles or rales that can be heard during a physical exam. Although most cases are viral, acute bronchitis can be caused by bacterial infection.

In the vast majority of cases, lab tests are not needed to diagnose the common cold.