Early and Late Phases of Asthma Exacerbations: Understanding the Differences

Asthma is considered a chronic (lifelong) lung disease, which involves both hyperactivity and inflammation in your airways. When diagnosed with asthma, your doctor may stage it as intermittent, mild, moderate, or severe.

While asthma stages are based on the severity and frequency of your symptoms, asthma phases describe how and when your body releases antibodies and inflammatory cells during an asthma attack.

Learning about both early and late phases of asthma exacerbations involves complex terminology and processes. In this article, we walk you through the basics so that you can learn more about the triggers of early and late phases of asthma attacks, as well as possible treatments that can target each phase.

Early phase asthma attacks

The early phase of an asthma attack develops when you inhale a trigger, such as air pollution or an allergen like pollen or animal dander. Airway inflammation and constriction begin in this phase.

Key players in the early phase

Sensitive immunoglobulin E (IgE) antibodies are often responsible for initiating the early phases of an asthma attack. These antibodies are pre-formed by your immune system, ready to respond when they encounter your asthma triggers.

Immunoglobulin antibodies are attached to mast cells, waiting to encounter their allergic trigger(s). Mast cells are a type of white blood cell that release chemicals as part of an immune response.

The mast cells go on to release the following:

  • cytokines: types of proteins that may increase airway mucus production and hyperactivity
  • leukotrienes: inflammatory substances your body releases in response to allergens
  • histamines: other types of chemicals released in response to allergens, increasing the risk of an allergic reaction
  • prostaglandins: types of lipids released during an injury or illness, known to increase inflammation

These chemicals are responsible for causing the smooth muscle in your airways to contract. In response, the airways tighten. Airway contraction and tightening may lead to bronchospasm.

Symptoms of early phase asthma attack

In an early phase asthma attack, you may experience bronchospasm, which involves constricted, narrowed airways. This can lead to breathing difficulties.

During this phase of asthma, you may experience the following symptoms:

  • inability to comfortably take a full breath in and out
  • wheezing
  • a frequent cough, with or without wheezing

Bronchospasm may also occur in other lung diseases, such as chronic obstructive pulmonary disease (COPD).

Overall, the early phase of an asthma exacerbation may last for a few hours, but you may not necessarily be able to differentiate the two phases based on symptoms alone.

Late phase asthma attacks

The late phase of an asthma attack typically develops several hours after the early phase. While symptoms may feel similar, there are more notable breathing difficulties due to a recurring airway blockage (obstruction) in this phase.

Key players in the late phase

Different types of cells activate in this phase, causing increased inflammation and subsequent contraction of the muscles in your lungs, called bronchoconstriction. Aside from mast cells, the following cells reach the lungs:

  • basophils, a class of white blood cells with enzymes that may be released during an asthma attack or allergic reaction
  • eosinophils, white blood cells that normally help fight infections
  • neutrophils, other types of white blood cells that protect your body from infections
  • TH2 cells, types of immune system cells that may increase inflammation and contribute to allergies and asthma
Symptoms of late phase asthma attack

During the late phase of an asthma attack, you may experience worsening breathing difficulties from bronchoconstriction. This can cause:

  • wheezing
  • coughing
  • shortness of breath

Additionally, airway obstruction may cause:

  • labored breathing
  • increased coughing
  • coughing up mucus
  • chest tightness

If you have exercise-induced bronchoconstriction (also called exercise-induced asthma), you may experience the above symptoms along with:

  • a notable decrease in endurance while playing sports or working out
  • sore throat
  • upset stomach
Eosinophilic asthma

Eosinophilic asthma is a subtype of asthma. It occurs when too many eosinophils are present during the late phase. While it can develop during childhood, most cases of eosinophilic asthma develop in adulthood.

Adults with this type of asthma may have a history of allergies. Nasal polyps are also common.

Its important to properly diagnose this asthma subtype. While it may cause symptoms similar to regular asthma, it usually requires additional treatments that aim to reduce the number of eosinophils in your airways.

Treatment for asthma

The goal of an asthma treatment plan is to help control the biological processes that cause an asthma attack. Your doctor will also recommend avoiding specific asthma triggers, such as allergens, air pollution, and chemicals.

While the exact treatment depends on the type and stage of asthma you have, common asthma treatments may target specific cells seen in both the early and late phases of asthma attacks, such as:

  • inhaled or oral corticosteroids reduce airway inflammation caused by various inflammatory cells
  • biologics, such as dupilumab, benralizumab, omalizumab and mepolizumab, target eosinophils, as well as basophils and IgE.
  • leukotriene modifiers, such as montelukast, inhibit leukotrienes
  • antihistamines for allergies, can reduce the effects of histamines
  • allergy shots (immunotherapy) help to gradually decrease sensitivity to specific allergens and reduce IgE antibodies

Additionally, everyone with asthma should have a short-acting inhaled bronchodilator (rescue inhaler) on hand in case of an asthma attack. These work by opening up the airways so you can breathe more easily.

You should seek emergency medical care if youre experiencing worsening symptoms despite taking a rescue inhaler for an asthma attack. Aside from increased wheezing and coughing, emergency symptoms may include blue skin and severely labored breathing.

Takeaway

Below is a summary of the key differences between the early and late phases of asthma exacerbations you can discuss with your doctor:

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