Asthma is an obstructive lung disorder that affects the normal functioning of the bronchi. The bronchi contain smooth muscle in their walls that control the entry of air into the lungs by the contraction or relaxation. The bronchi also have a role in warming and humidifying the air that enters the lungs, the removal of particulate matter, and the cough reflex (1). When these are not functioning properly, breathing can become difficult and laboured.

Approximately 5.4 people in the UK have asthma, which is 1 in every 12 adults and 1 in every 11 children. The condition is considered to be lifelong in most people, although people who develop asthma as children may find it goes away as they grow into adulthood (2). The prevalence of the disease has steadily increased since the second half of the last century (4).

There are various types of asthma, that indicate their development, triggers, and severity.

Allergic asthma is triggered by an allergen, and occurs more often in people who have another allergic condition such as hay fever, eczema and food allergies.

Seasonal asthma is only triggered at certain points in the year. This may be associated with seasonal allergies (such as to mould spores), or cold air.

Occupational asthma is when the disorder is directly caused by the environment the person is working in, and thus is typically diagnosed in adulthood. This may be a type of allergic asthma. The allergy could be, for example, to flour dust or latex dust (3).

Exercise induced bronchoconstriction is when asthma-like symptoms follow exercise, and is often a phenomenon found in athletes or others who frequently do strenuous activities. Exercise is inherently inflammatory and in this condition is more likely to cause broncho-constriction (3).

In difficult and severe (also known as brittle) asthma symptoms are difficult to control. Difficult asthma may require treatments in addition to inhalers. Severe asthma occurs in 4% of asthma sufferers and is diagnosed by a specialist. Those with severe asthma are treated with a class of drugs known as biologics, as even high doses of steroids do not control symptoms (3).

Asthma is treated with a variety of drugs, depending on how frequently symptoms are experienced and how well they are controlled.

• Step 1: Short acting beta-receptor agonist – This is an inhaled medication that is short-acting and considered a reliever therapy as it is a bronchodilator. This is prescribed to people with occasional, easily controlled symptoms, or in conjunction with other therapies. Ventolin and Salbutemol are in this category. These inhalers are often blue.
• Step 2: Inhaled corticosteroids – This is considered a preventer therapy, that is often used in addition to a reliever. Corticosteroids are anti-inflammatory. They may be added if the patient needs to use their preventer more than three times per week, is awakened by their asthma once per week, or who have recently experienced an exacerbation in symptoms. These inhalers are often brown or red.
• Step 3: An add-in therapy of a long-acting beta-receptor agonist, which is inhaled as a reliever. This may be in addition to inhaled corticosteroids. These inhalers are often purple.

If these steps do not sufficiently control symptoms, then a higher dose of the inhaled corticosteroid may be recommended with daily oral prednisolone (4).