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What Happens When You Cough?

An acute cough frequently goes along with a common cold. Even though that cough is unpleasant, annoying, and disruptive to everyday life, it actually serves as one of the body’s defense mechanisms.2 Inhaled foreign particles such as dust or pollen can be irritating or can be harmful to the respiratory system, and coughing is a way to clear the airways of potentially injurious substances. Cough is a reflex that requires a number of different sensors, nerves, and muscles to work together (Figure 1).3

Why Do We Cough?

Figure 1. Anatomical features of cough reflex.

Anatomy of the Cough

Special sensory proteins called “receptors” are found on the surface of some cells that line the upper respiratory tract.2 Locations in the body where these receptors are found include the back of the throat, the trachea (windpipe), and the upper bronchi where the trachea branches to the lungs. When these receptors are stimulated, they send a signal to sensory nerve fibers, such as those found in the vagus nerve.2 The sensory fibers transmit information to the brain for interpretation. The part of the brain that monitors the throat and upper airway region has been called the “cough center.” When the cough center receives a signal that the lining of airway is irritated the lining of the airway, muscles in the throat and chest receive action signals that trigger the cough mechanism, which is a 3-part process:4

  • First, a volume of air is inhaled.
  • Second, the opening to the trachea (the epiglottis) closes as the chest constricts, compressing the air within the lungs.
  • Third, the epiglottis opens, allowing a rapid burst of air to be expelled through the mouth.

Quotation marksEven though that cough is unpleasant, annoying, and disruptive to everyday life, it actually serves as one of the body’s defense mechanisms.Quotation marks

During a cold, mucus production in the airways increases, and coughing is how the body expels excess mucus from accumulating in the airways and lungs. Cough also can result from another common cold symptom, postnasal drip.2 Increased nasal secretions can run down the back of the throat and irritate sensitive cough touch points, creating the feeling that you need to clear your throat. This type of irritation also signals the brain to trigger the cough reflex. For many people, postnasal drip is especially annoying at night.

There are different ways that nonprescription products can help to relieve a cough and chest congestion (Table 1). Centrally acting cough suppressant medications are so named because they can act directly on the brain’s cough center.2 The most common of these is dextromethorphan (DM), which is found in many over-the-counter cough remedies. It can help reduce the sensitivity and activity of the cough center and prevent it from triggering a cough. Another class of ingredients is expectorants like guaifenesin, which help to make mucus thinner and easier to clear from the airways.2 The soothing action of a liquid cough medications can also play a role in their ability to provide relief. Liquid formulations can have a high viscosity, or thickness, can coat the throat and help reduce the irritation that is signaling the brain’s cough center.4

An understanding of the anatomy of cough and the nature of the cough reflex is an important part of knowing how to best provide relief.

Table 1. Different Approaches to Treat an Acute Cough and Chest Congestion
Class of Ingredient Mechanism of Action
Centrally acting cough suppressant (eg, dextromethorphan) Inhibits activity at sites in the brain
Expectorant (eg, guaifenesin) Thins mucus, making it easier to clear



  1. Dicpinigaitis PV, Colice GL, Goolsby MJ, Rogg GI, Spector SL, Winther B. Acute cough: a diagnostic and therapeutic challenge. Cough. 2009;5:11.
  2. Chung KF, Widdicombe JG, HA B, eds. Cough: Causes, Mechanisms, and Therapy.: Blackwell Publishing; 2003.
  3. Irwin RS, Rosen MJ, Braman SS. Cough. A comprehensive review. Arch Intern Med. 1977;137(9):1186-1191.
  4. Eccles R. Mechanisms of the placebo effect of sweet cough syrups. Respir Physiol Neurobiol. 2006;152(3):340-348.
  • †Robitussin Naturals are DIETARY SUPPLEMENTS. †Ivy Leaf relieves occasional cough and helps clear mucus associated with hoarseness, dry throat and irritants; non-naturally derived vitamin C (Immune Health gummies) and zinc (Immune Health liquids) support a healthy immune system.*
  • **True Source Honey is ethically and transparently sourced. Click here to learn more
  • ††Among leading cough and cold brands.
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  • This product contains the active ingredients Dextromethorphan.
  • *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
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