Asthma is a chronic medical condition that causes breathing difficulties. These difficulties result from the airways narrowing and swelling. Asthma can also lead to the production of mucus in your airways. Asthma may cause wheezing, shortness of breath, and coughing.

Asthma can be mild and need little or no medical treatment. However, it can also be severe and life threatening.

Medical professionals classify chronic asthma into four types ranging from mild intermittent to severe persistent. These types are determined by the frequency and severity of your asthma symptoms, along with results from objective testing, such as with a spirometer or a peak flow meter.

There are also different terms used to describe an acute asthma exacerbation, also known as an asthma attack. Asthma attacks are generally short lasting. Other types of asthma-related terms are used to describe certain asthma subtypes, or phenotypes.

Keep reading to learn how chronic asthma is classified, along with some terminology used to describe asthma and the different subtypes.

Chronic asthma classification

  • mild intermittent asthma
  • mild persistent asthma
  • moderate persistent asthma
  • severe persistent asthma

Acute asthma terminology

  • acute severe asthma
  • life threatening asthma
  • near-fatal asthma

Common asthma subtypes

  • nocturnal asthma
  • occupational asthma
  • allergic (atopic or extrinsic) asthma
  • nonallergic (nonatopic or intrinsic) asthma
  • child- vs. adult-onset asthma
  • seasonal asthma
  • exercise-induced asthma (also referred to as exercise-induced bronchoconstriction)
  • eosinophilic asthma

Asthma itself is considered a chronic, or long-term, lung disease, where symptoms may come and go. However, chronic asthma describes cases where you experience asthma symptoms more regularly.

Signs and symptoms may include:

  • wheezing or whistling when breathing
  • coughing
  • swollen airways
  • mucus in the airways

A doctor will determine the severity and control of your asthma based on how frequently you have symptoms and on your lung function, based on the results of spirometry and peak flow meter tests. Asthma can change from one category to another.

Chronic asthma is classified into four categories, according to the National Institutes of Health (NIH) 2007 Guidelines for the Diagnosis and Management of Asthma. While these guidelines received an update in 2020, the classification of asthma severity was not changed.

Mild intermittent asthma

Mild intermittent asthma means you experience symptoms, such as wheezing and coughing, up to 2 days per week. You may also have asthma flareups at night up to twice per month.

Any asthma symptoms that occur more frequently than this are considered “persistent.”

Mild persistent asthma

As the least severe type of persistent asthma, having mild persistent asthma means that you have symptoms greater than 2 days per week, but not daily. Nighttime symptoms can occur three to four times per month.

In mild persistent asthma, a person’s peak expiratory rate (PEF), a measure of their maximum speed of expiration, is greater than 80 percent of their predicted or personal best within the first second of breathing out, as measured with a peak flow meter. This test is performed when they are asymptomatic.

Moderate persistent asthma

With moderate persistent asthma, you’re likely to experience symptoms every day. Asthma flare-ups may last several days, somewhat limiting your participation in daily activities. Those with moderate persistent asthma can experience sleep interference at night at least once per week, though not nightly.

In untreated moderate persistent asthma, a person’s PEF falls within 60 to 80 percent, as measured during the first second of expiration using a peak flow meter.

Severe persistent asthma

Severe persistent asthma is the most serious, but least common form of chronic asthma. With this type of asthma, you experience symptoms throughout the day, every day.

Nighttime awakenings can occur as often as 7 times per week. You may experience severe limitations to your daily activities.

When untreated, severe persistent asthma can lead to a PEF of less than 60 percent of predicted or personal best, as measured during the first second of expiration with a peak flow meter.

Most people with asthma will not develop chronic obstructive pulmonary disease (COPD), and many people with COPD don’t have asthma. However, it’s possible to have both.

Asthma-COPD overlap syndrome (ACOS) occurs when someone has these two conditions at once.

How is it treated?

The goals of asthma treatment are to improve symptoms, reduce the risk of hospitalization and loss of lung function, and minimize adverse effects from asthma medications, like oral corticosteroids.

Effective asthma management typically focuses on prevention. This can mean regular visits where a doctor:

  • assesses your symptoms
  • monitors your lung function
  • adjusts your medications, if needed
  • provides education
  • discusses how you can avoid triggers

In general, people with mild intermittent asthma usually only need a rescue inhaler to treat their symptoms. You do not typically need daily medication, since your symptoms only occur occasionally.

However, chronic controller medications are usually necessary if you’re classified as having persistent asthma. It’s important that all people with asthma have immediate access to an inhaled bronchodilator with a rapid onset of action for quickly relieving asthma symptoms.

People with persistent asthma often need to take asthma medication daily. This can help keep their asthma under control, even if they do not experience daily symptoms. These medications are considered long-term control medications and they work by reducing inflammation in the airways.

Depending on the specific drug, long-term control medications can come in an inhaler or in tablet form.

The type a doctor prescribes, along with your dosage, can depend on your individual symptoms and their severity.

If your asthma is designated as moderate to severe, a doctor may prescribe more than one medication.

While long-term control medications can help reduce the frequency of your attacks, you will also need another medication if one occurs. It’s important to keep these medications on hand so you can treat symptoms as they arise.

For people with mild persistent asthma, a doctor may prescribe a low dose inhaled corticosteroid medication. An inhaled corticosteroid is taken by quickly inhaling it. It’s usually taken once or twice a day.

If your asthma is brought on by exercise, a doctor may instruct you to use your rescue inhaler before exercise to prevent symptoms.

Often called an “asthma attack,” acute asthma refers to a sudden worsening of this lung disease, causing symptoms that can include:

These symptoms may also occur with or without long-term treatment. While a rescue inhaler may be used during an acute asthma attack, acute asthma can be life threatening and require hospitalization.

The following terms may also be used to describe acute asthma flares.

Acute severe asthma

Acute severe asthma refers to a sudden onset of severe symptoms that you may experience throughout the day. This type of life threatening asthma exacerbation may be caused by stopping your asthma treatment plan or an acute illness, such as an upper respiratory tract infection.

With an acute severe asthma attack, you may experience additional symptoms that can include:

  • fast breathing
  • difficulty breathing while lying down
  • sweating
  • fast heart rate
  • inability to walk or talk
  • confusion

If you’re experiencing any of the above symptoms, you should call 911 or your local emergency services.

Life threatening asthma

In some cases, an acute asthma exacerbation may become life threatening. In fact, an estimated 25,000 to 50,000 people are admitted to intensive care every year in the United States due to life threatening asthma.

Life threatening asthma can cause a significant drop in blood oxygen, a condition called hypoxemia, or too much carbon dioxide, which is known as hypercapnia. Both can be caused by inadequate respiration.

At the hospital, treatment typically includes bronchodilator medications to help open the airways and steroids to decrease inflammation. Intubation or mechanical ventilation may also be required.

Near-fatal asthma

Near-fatal asthma describes symptom exacerbation that can be deadly without hospitalization. While the exact causes may vary, risk factors may include:

  • having a history of near-fatal asthma attacks
  • not taking your medication, or recently stopping your treatment plan
  • living in an urban environment
  • having a lack of access to quality health care
  • having other medical conditions such as cardiovascular disease

Aside from the chronic asthma classifications and acute asthma exacerbation, there are additional subtypes (phenotypes) used to provide insights into your asthma. They can also help predict how you may respond to treatment.

Characterizing your asthma may help identify specific triggers and guide the development of new treatments to help manage and prevent attacks.

The below subtypes may be chronic or acute, so it’s important to discuss them with your doctor and follow the appropriate treatment plan for each.

Nocturnal asthma

Nocturnal asthma refers to symptoms that occur at night. Triggers may include allergens in your bedroom, cooling of the airway, heartburn, and hormone secretions that follow a circadian pattern.

Nighttime symptoms may include:

  • chest tightness
  • shortness of breath
  • cough
  • wheezing

These symptoms can make it difficult to sleep and leave you feeling fatigued during the day.

Occupational asthma

Occupational asthma describes a type of asthma that develops as a result of regular exposure to substances at your place of work. These may include fumes, dust, and chemicals.

While it’s estimated that 15 percent of all new asthma cases are work related, occupational asthma may take several years to develop in some people.

Allergic asthma

If you have allergies, you may be at a higher risk of developing asthma. The exact triggers for allergic asthma can vary but may include:

  • pet dander
  • dust mites
  • pollen
  • mold
  • foods

The severity of your asthma symptoms can depend on how severe your allergies are.

Allergic asthma is the most common type of asthma and often requires treatment from an allergist or immunologist. Controlling your allergy symptoms and avoiding your triggers may help reduce future asthma attacks.

Aside from having a rescue inhaler on hand, allergic asthma treatments may include antihistamines, eye drops, leukotriene modifiers, and more.

Some people may benefit from allergy shots or be candidates for one of the biologic agents, such as anti-immunoglobulin E (anti-IgE) therapy. These therapies may help decrease asthma symptoms in people with severe asthma, according to a 2021 case study.

Nonallergic asthma

As the name suggests, nonallergic asthma is a type of asthma that is not related to an allergy trigger. This type of asthma may also be called nonatopic asthma.

Nonallergic asthma is less common than allergic asthma. Doctors don’t completely understand the causes of nonallergic asthma, but it often develops later in life. It may be more severe than allergic asthma.

Child- vs. adult-onset asthma

Asthma most often develops during childhood before the age of 5. This is referred to as childhood asthma or child-onset asthma. Up to 50 percent of children with asthma may experience improved asthma symptoms in early adulthood.

However, asthma can develop at any age. Asthma that starts during adulthood is called adult- or late-onset asthma, and it primarily affects women.

Seasonal asthma

Seasonal asthma describes exacerbations that you may experience with certain seasonal changes.

This may include outdoor seasonal allergens, such as pollen or mold. It can also include weather pattern changes, such as wind, rain, and hot or cold air.

Exercise-induced asthma

Also called exercise-induced bronchoconstriction (EIB), this type of asthma occurs during or after exercise. While up to 90 percent of people with asthma have EIB, not everyone with EIB has chronic asthma.

Exercise-induced asthma may be managed with traditional asthma treatments and by taking your rescue inhaler 15 to 30 minutes before any vigorous activity.

Eosinophilic asthma

Eosinophilic asthma is a severe type of chronic asthma caused by an increase of eosinophil blood cells that may inflame and damage lung tissues. It typically develops in adulthood and may be treated with traditional asthma treatments.

However, if you have this type of asthma and it doesn’t respond to typical medications, your doctor may recommend biologics, a form of severe asthma treatment given by injection.

Chronic asthma– intermittent
– mild persistent
– moderate persistent
– severe persistent
– wheezing
– coughing
– mucus in airways
– shortness of breath
depends on severity, and may require a combination of long-term and short acting treatmentslong term, with frequency of symptoms depending on subtype
Acute asthma– acute severe asthma
– life threatening asthma
– near-fatal asthma
same as chronic asthma, with additional, severe symptoms, such as inability to breatherequires bronchodilators, steroids, and oxygen therapy at the hospitalsudden onset
Asthma subtypes– nocturnal asthma
– occupational asthma
– allergic asthma
– nonallergic asthma
– child- vs. adult-onset asthma
– seasonal asthma
– exercise-induced asthma
– eosinophilic asthma
symptoms similar to chronic or acute asthma, depending on severitysimilar treatments to above, and allergy medications for allergic or seasonal asthma, or biologics for eosinophilic asthmachronic or sudden onset

With any type of asthma, educating yourself about your condition is important in managing your symptoms.

Everyone with asthma should also have an asthma action plan. An asthma action plan is developed with a doctor and lists the steps that you need to take in case of an asthma attack.

Since even mild asthma has the possibility of increasing in severity, you should follow the treatment plan from the doctor and have regular checkups.

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