Coughing is a common reflex during illness, often causing discomfort. While perceived as an irritating symptom, a cough is a natural, protective bodily reflex. It helps clear the airways of irritants and foreign substances, maintaining respiratory health. Understanding why we cough when sick involves exploring the mechanisms behind this reflex and how illnesses activate it.
The Body’s Coughing Mechanism
It begins when sensory receptors, such as mechanoreceptors and chemoreceptors, detect irritants, mucus, or foreign particles within the respiratory tract, particularly in the larynx, trachea, and bronchi. These receptors transmit sensory information through afferent nerves, primarily via the vagus nerve, to the medulla in the brainstem, which acts as the cough center. The brainstem then coordinates a series of muscle actions through efferent pathways.
The cough reflex involves three main phases: an inspiratory phase, a compressive phase, and an expulsive phase. During the inspiratory phase, the vocal cords open, and the diaphragm and external intercostal muscles contract, allowing a deep breath to fill the lungs. Next, in the compressive phase, the epiglottis and vocal cords close, trapping air within the lungs while abdominal and intercostal muscles contract forcefully, building significant pressure. Finally, the expulsive phase occurs as the vocal cords relax and the glottis opens, releasing air rapidly and forcefully to expel irritants from the airways.
Illnesses That Cause Coughs
Several common illnesses trigger the cough reflex through different mechanisms. Viral infections, such as the common cold, frequently lead to coughing due to inflammation of the upper airway structures and increased mucus production, which irritates the throat and airways. Post-nasal drip, where mucus drains down the back of the throat, is another common trigger associated with colds. Influenza, or the flu, also causes widespread inflammation of the respiratory tract, leading to more severe coughing fits compared to the common cold.
Bronchitis involves inflammation of the bronchial tubes. This inflammation often results in increased mucus production and irritation, prompting the body to cough to clear secretions. Pneumonia, a lung infection, causes inflammation and fluid buildup in the air sacs, and coughing helps to expel the infected material. Allergies can also induce coughing as the body reacts to irritants like pollen or dust, leading to inflammation and excess mucus in the airways. Asthma, characterized by airway constriction and inflammation, triggers coughing as the body attempts to clear narrowed passages.
Decoding Your Cough Type
The characteristics of a cough can offer clues about its underlying cause. A dry cough indicates irritation or inflammation in the airways without significant mucus production. Conversely, a wet or productive cough is characterized by the expulsion of mucus or phlegm from the respiratory tract. This helps clear secretions associated with infections or conditions that produce excess fluid.
Coughs are also categorized by their duration. An acute cough lasts for less than three weeks, commonly associated with temporary conditions like the common cold or flu. When a cough persists for more than three weeks, it is considered a persistent or chronic cough. Such prolonged coughing can indicate underlying issues, including lingering post-nasal drip, asthma, or gastroesophageal reflux disease (GERD).
When to Be Concerned About a Cough
While many coughs resolve on their own, certain signs warrant prompt medical attention. Coughing up blood, even in small amounts, is a significant warning sign that requires immediate evaluation. Experiencing severe difficulty breathing or shortness of breath alongside a cough also indicates a potentially serious respiratory problem. A high fever, when accompanied by a cough, suggests a more significant infection that may need treatment.
Chest pain associated with coughing can be a symptom of conditions ranging from muscle strain to more serious lung or heart issues. A cough that lasts longer than a few weeks, especially if worsening, should be assessed by a healthcare professional. Unexplained weight loss, night sweats, or a cough that initially improves but then significantly worsens are additional indicators that medical advice is needed.
Managing Coughs at Home
Many coughs can be managed effectively with simple home remedies that provide symptomatic relief and promote comfort. Staying well-hydrated by drinking plenty of water, warm fluids like tea, or broth helps thin mucus, making it easier to clear from the airways. Using a humidifier in your home or taking a steamy shower can also help moisten the air and soothe irritated airways, reducing the intensity of a cough.
Honey has been shown to be effective in soothing coughs for adults and children over one year of age. Over-the-counter cough suppressants can help reduce the urge to cough, while expectorants may assist in loosening and expelling mucus, though these should be used according to package directions. Getting adequate rest supports the body’s immune system in fighting off the underlying illness. Avoiding irritants such as smoke, dust, and known allergens can also prevent further irritation and reduce coughing.