In plain words
Asthma is a long-term lung disease in which inflammation and tightening of the muscle around the airways make it harder to breathe. It can affect people of any age and is the most common chronic disease among children.
Key facts
- WHO estimated 363 million people had asthma in 2023 and that it caused 442,000 deaths.
- Most asthma deaths occur in low- and lower-middle-income countries, where under-diagnosis and under-treatment are a problem.
Symptoms
A persistent cough (often at night), wheezing, shortness of breath and chest tightness. Symptoms come and go, are often worse at night or with exercise, and can suddenly worsen in an asthma attack. Other conditions can cause similar symptoms, so a health professional should assess them.
Triggers
Colds, weather changes, dust, smoke, fumes, pollen, animal fur and feathers, strong soaps and perfume.
Causes and risk
There is usually no single cause. Risk is higher with a family history, other allergic conditions such as eczema or hay fever, urbanisation, early-life factors (low birth weight, prematurity, tobacco smoke, air pollution, viral respiratory infections), allergens and irritants, occupational exposure, and overweight or obesity.
Treatment
Asthma cannot be cured but can be treated. WHO says inhaled medication, delivered by an inhaler directly to the lungs, can control symptoms and let people live a normal, active life, and avoiding triggers helps.
Sources
- WHO fact sheet, Asthma, published 28 April 2026, read 9 October 2026.
Last reviewed: 9 October 2026. Reviewer: none yet. This page is general education and is not medical advice. Figures are WHO's and may have been updated since.