What Is the Cough Reflex & How Does It Work?

The cough reflex causes every cough you experience. Cough receptor locations throughout your airway recognize irritants that may need to be cleared. These sensors send a signal to your brain, which activates coughing muscles in your chest and abdomen. The result is an expulsion of air traveling up to 100 miles per hour, clearing anything in its way in order to keep your respiratory system healthy.

Continue reading to learn more about the cough reflex, including how coughing works and what happens in your body when you cough. 

Cough Reflex Arc

The cough reflex is designed to keep your airways clear so that you can continue breathing. The cough reflex is activated when your body senses anything that could pose a threat to breathing. This could be a mechanical item, like mucus that blocks part of your airway, or a chemical item like spicy food or smoky air. 

Once your body senses the need to cough, the cough signal travels through three different pathways. This is known as the cough reflex arc. 

Sensory Afferent Pathway

The sensory afferent pathway is the first step of the cough reflex arc. This is the point at which your body recognizes that there is an irritant it needs to clear from the airway. 

There are cough receptors spread throughout your upper airway and lead all the way down to your diaphragm. There are cough receptors in your airway, voice box, and lungs. These sensory nerve fibers are tied to the vagus nerve.

Some fibers are attuned to detect a mechanical input, like something blocking the airways, while others detect chemicals or heat. At this stage in the cough reflex arc, the sensors detect a problem and send a signal to your brain.

Central Pathway

The central pathway is the second step in the cough reflex arc. Once the receptors detect a problem, they send signals to the brain through the vagus nerve. This travels to the medulla oblongata, an area of the brain located between the brain stem and the pons, which controls critical functions like circulation, breathing, and coughing.

When the signal for the need to cough is received in the medulla oblongata, this area of the brain uses motor neurons to activate coughing muscles. 

Motor Efferent Pathway

The third and final stage of the cough reflex arc is the motor efferent pathway. During this stage, motor neurons activate a series of actions in the coughing muscles. The diaphragm, larynx, intercostal muscles (muscles in the rib cage), and abdominal muscles all contract at once, causing the coughing sensation that we’re all familiar with.

Cough Reflex Phases

Understanding the cough reflex arc is interesting, but it can be a bit abstract. The cough reflex phases help you understand what you experience when you cough. The cough reflex has three phases. 

Inspiratory Phase

In the first stage, the inspiratory phase, your body is taking in more air. After the cough receptors detect an irritant, your muscles contract to let more air enter your lungs. First, the vocal cords open widely, allowing you to take the deep breath that often precedes a cough. Next, your external intercostals (the muscles between your ribs) contract. At the same time, the diaphragm contracts, allowing your lungs to fill fully.

Compression Phase

During the second stage, the compression phase, the air in your lung becomes pressurized. First, the epiglottis, the flap that covers the top of your windpipe, closes. The vocal cords also close, and the air pressure builds.

Expiratory Phase

The final stage, or expiratory phase, is the cough that we’re all familiar with. At this stage, the intercostal muscles and abdominals contract. The epiglottis and vocal cords open, allowing the air to quickly be expelled from the lungs. The force of the air clears the contaminants that prompted the cough.

Conditions and Complications

The cough reflex is an important evolutionary adaptation that keeps people healthy. Coughing expels not only contaminants and irritants but also viruses and bacteria that might make you sick. However, the cough reflex can become unhealthy or frustrating in some people. 

If you’re coughing often, you may not get enough sleep. Coughing can also be painful and interrupt normal activities like exercise or making professional presentations. For these reasons, cough is one of the most common concerns for which people see their healthcare provider.

Chronic cough is a condition in which the cough reflex is regularly activated. There are many causes of chronic cough, including:

• Asthma
• Allergies
• Postnasal drip
• Acid reflux

Recently, the medical community and researchers have been exploring cough hypersensitivity syndrome. Researchers propose that people with cough hypersensitivity syndrome have cough receptors that are very sensitive to even low levels of irritants, including heat or cold. This could explain why some people have chronic coughs that don't have another explanation. 

Cough Treatment

If you have a chronic cough, there are various treatments that you can try, including home remedies, over-the-counter (OTC) medications, and prescription medications. 

To know what treatment is best for you, you have to identify what’s triggering your cough reflex. If you’re coughing because of postnasal drip caused by seasonal allergies, taking an allergy medication could help. On the other hand, if your cough is triggered by an underlying condition like gastroesophageal reflux disease (GERD), or acid reflux, you’ll need to treat that condition. 

Some remedies, like cough drops, honey, and hot water focus on soothing the cough receptors so they’re not triggering the need to cough. 

Blocking the Cough Reflex

If your cough seems to be triggered for no reason, you can talk to your healthcare provider about using a cough medication that blocks the cough reflex. This is done with medication that has the active ingredient dextromethorphan. Dextromethorphan blocks the brain signals that cause cough. It’s found in medications including:

• Delsym
• Dimetapp
• Theraflu
• Robitussin

Dextromethorphan can be dangerous in some cases, so always talk to your healthcare provider about whether it’s safe for you. 

Summary

Coughing is extremely common, but it's caused by a complex process unfolding in the body. Cough receptors in your airways detect irritants like particles, chemicals or warm or cold air. They send a message through the vagus nerve to the medulla oblongata, an area of the brain.

That then uses motor neurons to cue the muscles involved in coughing. Once this happens, the airway expands to take lots of air into the lungs. The air is pressurized, and then it's expelled at a high speed in order to clear away the irritants. 

A Word From Verywell 

The cough reflex is a natural response your body uses to keep you healthy. However, having a problem with your cough reflex can wreak havoc on your well-being. Talk to your healthcare provider about any cough that lasts for more than two weeks, so that you can get back to feeling like yourself.