Conditions · Chest

Asthma !

Asthma is a long-term inflammation of the airways that makes them narrow in episodes, causing wheezing, breathlessness, chest tightness and cough.

Updated 2026-10-30

Structures involved

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In biochemistry

In immunology

In histology

In the clinical exam

In physiology

Why it happens

What it is

Chronic inflammatory disease of the airways with variable, largely reversible airflow obstruction and hyperresponsiveness, causing recurrent wheeze, breathlessness, chest tightness and cough.

Who gets it

One of the most common chronic diseases in children and young adults; in Colombia and Latin America it is often under-diagnosed or under-treated, causing avoidable emergency visits. In ISAAC phase 3 (2002–2003), 11.8% of adolescents in three Colombian centres had current asthma, and a national study found 6.3% of Colombian adults with a medical diagnosis.

Causes

Allergic (atopic) airway inflammation, often type 2
Triggers: dust mites, animal dander, pollen, moulds
Viral respiratory infections
Exercise and cold air
Smoke, air pollution and occupational exposures
Aspirin or NSAID sensitivity in some patients

Risk factors

Personal or family history of atopy (eczema, allergic rhinitis)
Exposure to tobacco smoke, including in pregnancy
Obesity
Indoor and outdoor air pollution
Early-life viral infections
Occupational sensitisers

Pathophysiology

Airway inflammation with eosinophils, mast cells and Th2 cytokines makes bronchi hyperresponsive. Triggers cause smooth-muscle contraction, mucosal oedema and mucus plugging, which narrow the airway reversibly. Chronic disease can lead to airway remodelling with partly fixed obstruction.

Classification

By control: well controlled, partly controlled, uncontrolled
By severity: defined by the treatment step needed for control
Phenotypes: allergic, non-allergic, eosinophilic, exercise-induced, occupational

Symptoms and signs

Episodic wheeze
Shortness of breath
Chest tightness
Cough, often at night or early morning
Symptoms triggered by exercise, allergens, cold air or infections
Expiratory wheeze and prolonged expiration on examination

Diagnosis

Clinical: Typical variable symptoms with triggers; a history of atopy supports it. Examination may be normal between attacks.
Tests: Spirometry shows obstruction (reduced FEV1/FVC) with a significant bronchodilator response; peak-flow variability, bronchial challenge tests or FeNO help when spirometry is normal. Blood eosinophils and IgE for phenotype.
Imaging: Chest X-ray is usually normal; it is used to exclude other causes or complications such as pneumothorax.

Differential diagnosis

COPD
Vocal cord dysfunction
Heart failure (cardiac asthma)
Foreign body or airway tumour
Bronchiectasis
GERD-related cough

Goal of treatment

Achieve good symptom control, prevent exacerbations and loss of lung function, and minimise medication side effects with the lowest effective treatment step.

Treatment

Medical: Controller therapy: inhaled corticosteroids as the basis, with long-acting beta-2 agonists added at higher steps; leukotriene receptor antagonists as alternatives.
Medical: Reliever therapy: short-acting beta-2 agonists or a low-dose inhaled corticosteroid–formoterol combination as needed, per current guidelines; biologics for severe eosinophilic or allergic asthma.
Acute: Severe exacerbation: oxygen, repeated inhaled bronchodilators (beta-2 agonists plus antimuscarinics), systemic corticosteroids and, in selected cases, intravenous magnesium.
Lifestyle: Trigger avoidance, smoke-free environment, inhaler technique education and a written action plan.
Follow-up: Regular review of control, exacerbations and lung function to step treatment up or down.

Drugs for this condition

Complications

Life-threatening exacerbation and respiratory failure
Pneumothorax or pneumomediastinum
Airway remodelling with fixed obstruction
Side effects of repeated systemic corticosteroids

Prognosis

Most patients achieve good control with regular controller therapy and good inhaler technique. Childhood asthma often improves in adolescence; poor adherence and previous near-fatal attacks predict worse outcomes.

Prevention

Avoidance of tobacco smoke and known triggers
Influenza vaccination
Adherence to controller therapy to prevent exacerbations

Test yourself

Think of the answer, then tap the question to see it.

What spirometry finding supports a diagnosis of asthma?

Airflow obstruction (low FEV1/FVC) with a significant improvement in FEV1 after a bronchodilator, showing reversibility.

What is the cornerstone controller medication class in persistent asthma?

Inhaled corticosteroids, which reduce airway inflammation and the risk of exacerbations.

Why is a silent chest an ominous sign in an asthma attack?

It means airflow is so reduced that no wheeze is heard: a sign of life-threatening obstruction and impending respiratory failure.

How does asthma differ from COPD in its airflow obstruction?

In asthma obstruction is variable and largely reversible; in COPD it is persistent and not fully reversible after a bronchodilator.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Asthma (StatPearls (NCBI Bookshelf), 2024); Asthma: epidemiology of disease control in Latin America - short review (Asthma research and practice, 2017) · adapted, CC BY 4.0.

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Representative model, for educational purposes only.

Segmental bronchi highlighted on the Durgical 3D model