The Canadian Asthma Consensus Guidelines recommend the treatment of asthma be considered on an individual patient basis and carefully assessed in terms of the impact on symptoms and lung function. Inhaled corticosteroids are considered to be the mainstay of asthma treatment, and they work by reducing the inflammation in the lung and airway that causes asthma.

According to the guidelines, medications used to treat asthma are divided into two main categories: controllers (preventers) and relievers.

• Controllers (preventers) include anti-inflammatory medications, such as inhaled corticosteroids (ICS). These agents are taken regularly to control asthma.
• Relievers, which include short-acting beta₂-agonists, are used to relieve acute asthma symptoms on demand at the minimum dose and frequency required.

ICS medications are the most effective controllers and are considered first-line anti-inflammatory therapy. They offer the best option for the initial anti-inflammatory treatment of asthma and are the mainstay of asthma therapy. ICS are clearly indicated for all patients, aside from those with a very mild form of the disease, and are very effective in:

• preventing persistent symptoms;
• improving lung function;
• decreasing airway hyper-responsiveness; and,
• reducing morbidity.

When best results are achieved with an ICS, the dose should be reduced to determine the minimum amount required to maintain control of the disease. All asthma medications should be used at the lowest dose and frequency required to maintain acceptable asthma management, and treatments should not be used as a substitute for proper control of the environment.