Asthma

What it is

Asthma is a chronic inflammatory airway disease that affected an estimated 363 million people worldwide in 2023. It causes episodes of cough, wheeze, chest tightness, and shortness of breath because the airways become inflamed, overly sensitive, and temporarily narrowed. Symptoms often vary over time and may worsen at night, with exercise, during viral infections, or after exposure to triggers such as dust, smoke, pollen, fumes, or cold air.

A key point is that asthma is usually treatable and controllable, but it is not considered curable. Diagnosis is not based on symptoms alone. Clinicians usually look for a pattern of typical symptoms plus evidence of variable expiratory airflow limitation, most often on spirometry. Asthma can begin in childhood or adulthood, and severity ranges from occasional mild symptoms to severe attacks that need emergency care.

Common patterns include:

Pattern	What it means
Intermittent symptoms	Symptoms come and go, with symptom-free periods
Persistent asthma	Symptoms occur more regularly and may affect sleep or activity
Trigger-related asthma	Symptoms flare with exercise, allergens, work exposures, infections, or weather changes
Exacerbation or asthma attack	Sudden worsening that may require urgent treatment

In India, asthma is a common chronic respiratory condition, and control can be affected by air pollution, biomass smoke exposure, tobacco smoke, occupational dusts, and limited access to inhaled medicines in some settings.

How it works

Asthma involves ongoing inflammation of the bronchial tubes, the air passages that carry air in and out of the lungs. In susceptible people, the airway lining becomes inflamed and swollen, the muscles around the airways tighten, and mucus production may increase. These changes narrow the airway opening and make breathing harder.

Another important feature is bronchial hyperresponsiveness, meaning the airways react too strongly to triggers that might not affect other people. This is why a cold, smoke exposure, exercise, or allergens can cause a flare.

Over time, some people can develop structural airway changes called remodeling. This may contribute to more persistent symptoms and less reversible airflow limitation. Early diagnosis and good control are therefore important.

Typical triggers include:

1. Viral respiratory infections
2. House dust mites, pollen, molds, and animal dander
3. Tobacco smoke and air pollution
4. Exercise, especially in cold dry air
5. Workplace irritants such as chemicals, dust, or fumes
6. Strong odors, weather changes, and sometimes certain medicines

Evidence and uses

Asthma treatment aims to reduce daily symptoms, prevent severe attacks, preserve lung function, and maintain normal activity. Modern guidelines support a stepwise approach, meaning treatment is adjusted up or down depending on symptom control and risk of exacerbations.

The main treatment groups are:

Treatment type	Main role
Inhaled corticosteroids (ICS)	Reduce airway inflammation and lower attack risk
Bronchodilators	Relax airway muscles and relieve narrowing
ICS-formoterol combinations	Used in many patients as reliever and/or controller therapy
Leukotriene receptor antagonists	Alternative or add-on option in selected patients
Biologic therapies	For some people with severe asthma driven by specific inflammatory pathways

A major evidence-based point is that controller therapy with inhaled corticosteroids reduces exacerbations and improves symptom control. Over-reliance on quick-relief inhalers without anti-inflammatory treatment is linked to poorer outcomes. For many adolescents and adults, current guideline-based care favors inhaled corticosteroid-containing treatment even in milder disease, rather than using a short-acting bronchodilator alone.

Non-drug measures also matter. Identifying triggers, avoiding tobacco smoke, improving indoor air quality, checking inhaler technique, and following a written asthma action plan can reduce attacks. Vaccination against respiratory infections may also help lower risk of flare-ups in some patients.

Traditional or herbal remedies are sometimes used by patients, including in India, but they should not replace proven asthma medicines. Evidence for most herbal or Ayurvedic products in asthma is limited, mixed, or of low quality, and some products may interact with medicines or delay effective treatment.

Diagnosis / how it's measured

Asthma can be suspected from the history, but diagnosis usually needs objective testing. The core test is spirometry, which measures how much air a person can blow out and how quickly.

Clinicians look for variable airflow obstruction, often shown by improvement after a bronchodilator. Peak expiratory flow monitoring over time may also help when spirometry is not immediately available. Additional tests can include allergy evaluation, fractional exhaled nitric oxide in some settings, and tests to rule out other causes of wheeze or breathlessness.

Diagnosis often includes these elements:

Diagnostic element	Why it matters
Typical symptoms	Wheeze, cough, chest tightness, breathlessness that vary over time
Spirometry	Confirms airflow limitation and reversibility
Trigger pattern	Helps identify allergens, exercise, work exposures, or infections
Control assessment	Tracks day symptoms, night waking, reliever use, and activity limits
Exacerbation history	Predicts future risk and need for stronger prevention

Conditions that can mimic asthma include chronic obstructive pulmonary disease, vocal cord dysfunction, heart failure, respiratory infections, gastroesophageal reflux, and anxiety-related breathing symptoms.

When to see a clinician

See a clinician if you have repeated wheezing, nighttime cough, chest tightness, or shortness of breath, especially if symptoms recur with exercise, colds, smoke, or allergens. Early assessment can help confirm the diagnosis and prevent avoidable attacks.

Seek urgent or emergency care if breathing is rapidly worsening, you are struggling to speak in full sentences, your reliever inhaler is not helping, your lips or fingertips look blue, or symptoms occur even at rest. Severe asthma attacks can be life-threatening.

People already diagnosed with asthma should seek review if they need their reliever inhaler more often, wake at night with symptoms, miss work or school because of breathing problems, or have had an emergency visit, oral steroid course, or hospitalization.

Limitations and open questions

Asthma is a well-studied disease, but important uncertainties remain. Not all asthma is the same. Different inflammatory patterns and triggers mean that one treatment plan does not fit everyone, especially in severe asthma.

Diagnosis can also be difficult because symptoms overlap with other conditions and may be absent during a clinic visit. Spirometry access is uneven in many regions, including some parts of India, which can lead to both under-diagnosis and over-diagnosis.

Research continues on better biomarkers, prevention strategies, and ways to predict which children will outgrow symptoms and which patients will develop persistent disease. There is also ongoing work on reducing asthma burden in low- and middle-income countries, where under-treatment and avoidable deaths remain major problems.