What Is Bronchoconstriction?

Bronchoconstriction is tightening of the smooth muscles of the bronchi and bronchioles (airways), causing the airways to become narrow and obstructing the movement of air into and out of the lungs. Bronchoconstriction is characteristic of asthma as well as lung diseases such as emphysema, viral infections, stress, and other health concerns.

Bronchoconstriction can lead to a respiratory emergency, such as an asthma attack, which must be treated with inhaled medication to relieve symptoms. Future occurrences can be prevented with medication, trigger avoidance, and/or other treatments (depending on the cause).

Types of Bronchoconstriction

Airway constriction is a symptom of many medical conditions but most often is associated with various types of asthma and asthma-like conditions.

For example:

• Allergic asthma: An allergy activates the immune system, causing the release of chemicals that lead to inflammation and cause constriction of the airways. Symptoms of bronchoconstriction typically do not develop in response to the first exposure to an allergen. Problems typically occur during the second exposure or later.
• Exercise-induced bronchoconstriction (EIB): With EIB, breathing changes during physical activity directly result in the narrowing of the airways. EIB occurs during or immediately after exercise for some people with asthma or other lung diseases, but it can also occur in otherwise healthy individuals.

Among other lung diseases associated with susceptibility to bronchoconstriction:

• Chronic obstructive pulmonary disease (COPD)
• Emphysema
• Chronic bronchitis

In people with these conditions, bronchoconstriction often is triggered by irritants, such as cigarette smoke, dust, or other air pollutants. This isn't an allergic reaction but a direct irritation of the airway tissues. Several other things can trigger bronchoconstriction in susceptible people as well.

Bronchoconstriction Symptoms

As the airways that carry air to and from the lung constrict, several breathing-related problems can occur. Some may be minor and easy to overcome. However, if the symptoms do not resolve on their own or with medication and/or are severe, they can lead to serious complications.

Symptoms of bronchoconstriction due to any cause are similar to typical asthma symptoms and include:

• Shortness of breath
• Chest tightness
• Chronic cough
• Wheezing

In rare instances, bronchoconstriction can cause serious medical complications or fatality. In most cases, however, these episodes can be managed with proper treatment.

Shortness of Breath

When airways are constricted, it becomes difficult to get enough air into the lungs to support body functions. In response, the brain sends out a signal that you need to breathe faster to get more oxygen.

These brief, rapid inhalations are characteristic of shortness of breath. While the intent is to get more air inside the lungs, as long as the airway is narrowed, the need for more oxygen will persist. If shortness of breath continues, it can lead to oxygen deprivation, which can cause confusion or loss of consciousness.

Chest Tightness

Chest tightness is the feeling that a band around your chest is preventing you from pushing air in and out of your lungs. It can begin at the same time as other symptoms or occur after they’ve started.

This sensation and the feeling that you can't control your breathing can cause anxiety that only worsens your symptoms.

Chronic Cough

A chronic cough is one that can't be soothed. In the case of bronchoconstriction, cough receptors are stimulated as the airway is narrowed, although why this occurs is not well understood.

The result is a cough that is dry and non-productive, which means there is no phlegm or mucus involved. Instead, the cough sounds raspy, dry, and wheezy. 

Wheezing

Wheezing is the high-pitched sound that you make when you inhale or exhale through a narrowed airway. Wheezing after physical activity may be the first sign of asthma or EIB, especially in children.

While this is not a life-threatening symptom, it can alert you to the fact that you are at risk for asthma attacks. Discuss the possibility of EIB, asthma, or other lung problems with your healthcare provider.

Causes

The process of bronchoconstriction starts when something triggers the muscles along the airways to tighten. This squeezes the bronchi and bronchioles, which narrows your airway. In susceptible people, a variety of stimuli in the airway can cause tightening.

Healthcare providers don't yet understand the full process, but evidence suggests certain stimuli trigger multiple complex responses from your body that have to do with specialized immune-system cells, blood circulation, and nerves. Genetics may also play a role.

Further complicating the matter, different triggers can cause bronchoconstriction in different ways.

Allergens, irritants, and cold air are the most common triggers.

Allergens and Irritants

For some people, seemingly harmless materials or natural elements are seen by the immune systems as foreign and dangerous. Exposure to these substances produces antibodies called immunoglobulin E (IgE), which release chemicals (such as histamine) that cause bronchial inflammation and constriction that blocks normal airflow.

Common asthma triggers include:

• Cockroaches
• Dust mites  
• Mold
• Pets
• Pollen

Irritants cause bronchoconstriction via a biological process that's similar but involves a different mix of cells and chemicals in your body. Common airway irritants include:

• Environmental chemicals
• Gases
• Smoke
• Particulates
• Dust
• Strong odors

Even if you're not allergic to them, airborne pollen and dust can irritate your airways too.

Inhaling Cold Air

Bronchoconstriction occurs in people who are sensitive to cool air traveling through their airways. This is a particular concern for those with EIB.

When you exercise, you breathe in through your mouth as you try to pull in more oxygen to keep up with the physical exertion. The air you breathe in through your mouth is cooler than the air you breathe in through the nose.

If you're exercising in a cold environment, such as outdoors in the winter, the low-temperature air may trigger a reaction that causes the muscles around your airways to contract.

Research shows people susceptible to cold-weather muscle tightening of the airways include those with lung disease as well as healthy people—even high-level athletes—with no known lung ailments.

Other Triggers

While less common, numerous other stimuli can cause bronchoconstriction in susceptible people, including:

• Viral infection: In susceptible people, some viral infections appear to increase sensory-nerve activity. This leads to changes in how the nervous system controls the airways, resulting in bronchoconstriction.
• Sudden temperature changes: An extreme temperature change is believed to trigger sensory nerves to send signals to the autonomic nervous system that lead to bronchoconstriction.
• Gastroesophageal reflux disease (GERD): In some cases, stomach acid in the esophagus irritates nerves. In other cases, stomach contents may enter the lungs themselves. Both events start processes that end in tightened airways.
• Psychological stress: Physiological components of psychological stress may lead to changes in the vagus nerve and central nervous system that trigger bronchoconstriction.
• Strong emotions: Anger, fear, yelling, crying, laughing, and excitement all can lead to bronchoconstriction through changes in breathing and muscle tension.

Diagnosis

The initial diagnosis of bronchoconstriction is based on self-reported symptoms. Your healthcare provider will investigate to determine what triggers the constriction. The evaluation will include a complete history, physical examination, and pulmonary function testing.

An EIB diagnosis usually requires an exercise test. Your practitioner will use spirometry to measure your lung function before and after exercise. The test may include checking your tolerance of cold air.

To determine whether bronchoconstriction is caused by an allergen, you will need to undergo allergy testing. This may include skin tests in which common allergens are placed on or just under the top layer of your skin to see if you have a response. Blood tests may also be done to see how your immune system reacts when you're exposed to possible allergens.

If the cause of your symptoms isn't clear at that point, your healthcare provider may perform other tests and evaluations determined by the specifics of your case. These may be tests for other lung-related problems or other conditions with similar symptoms.

Similar Conditions

Some conditions have symptoms very similar to asthma and bronchoconstriction but aren't actually related to them, including vocal cord dysfunction and cardiac asthma.

In vocal chord dysfunction, restricted breathing is caused by the vocal cords closing over the airways, not a tightening of the airways themselves.

Despite what its name suggests, cardiac asthma isn't really a type of asthma. It's a symptom of left-sided heart failure, which causes breathing problems due to fluid accumulating in the lungs (pulmonary edema).

These distinctions are important, as vocal chord dysfunction and cardiac asthma don't respond to the same treatments as bronchoconstriction and asthma.

Treatment

The first step in treating bronchoconstriction is determining what your triggers are and avoiding them. While this sounds easy, it can be challenging. Many times you need to act like a detective, recording your symptoms, habits, and exposures and looking for links between them.

If your trigger is another condition, such as GERD or viral infection, treating that condition will likely improve your bronchoconstriction.

If you have frequent episodes brought on by stress or strong emotion, your healthcare provider may recommend stress management training or mental health counseling.

Medication

When an attack does occur, rescue inhalers are the first medication used to treat bronchoconstriction. Using the inhaler, you breathe the medications into your airways. Following a bronchoconstriction episode, your healthcare provider may prescribe an inhaler that you can use in case of future attacks.

• Short-acting beta agonists (SABAs): SABAs such as albuterol are called rescue inhalers. They can ease symptoms and protect against future episodes for about four to six hours. For EIB, your practitioner may advise you to use this inhaler 15 minutes before you exercise.
• Long-acting beta agonists (LABAs): LABAs such as Serevent (salmeterol) are daily control medications. When used regularly, they can prevent bronchoconstriction for up to 12 hours.

SABAs and LABAs relax the smooth muscles that line the airways, allowing them to open again so breathing can return to normal and symptoms cease. In addition to easing symptoms during an attack, these medications can prevent exercised-induced bronchoconstriction from occurring.

SABAs and LABAs do not decrease underlying inflammation, however. Your healthcare provider may also prescribe an inhaled steroid, which is a powerful anti-inflammatory medication.

In addition to these common treatments, other medical approaches that might be used include:

• Leukotriene receptor antagonists
• Ipratropium
• Mast cell stabilizers

Coping

If you're at risk for bronchoconstriction, you should always have your rescue inhaler handy. This can be particularly important for EIB since bronchoconstriction can be prevented by using your inhaler before activity.

Even if you're not diagnosed with asthma, you and your healthcare provider should develop a plan that outlines what triggers to avoid.

If you're an athlete who doesn't want to stop enjoying exercise, you might consider replacing endurance sports with activities that require shorter bursts of exercise, which may help you avoid bronchoconstriction.

Some simple measures, such as wearing a scarf over your mouth when it's cold or a mask during allergy season, may make a big difference in your symptoms.

A Word From Verywell

While bronchoconstriction can be frightening, especially the first few times it happens, you have options for getting and keeping it under control. Working closely with your healthcare provider, sticking to your treatment regimen, and avoiding irritants whenever possible can keep you breathing freely and living fully.