For mild to moderate asthma, inhalers provide an effective, safe and easy to use treatment that delivers drugs directly to the airways. As only very small quantities of the drug will get into the bloodstream, systemic side effects are minimal or negligible.

The attachment of a spacer device to the inhaler helps increase the delivery of drugs and is particularly useful in small children or those whose inhaler technique is not optimal. Medication designed for inhalation can also be delivered via nebulisers, ‘misting machines’, which are driven either by battery or plugged into the mains.

There are two main types of asthma medication:

• Relievers, also called short-acting bronchodilators: often delivered in a blue or white inhaler, these work quickly and can produce almost immediate relief from mild to moderate chest tightness. Relievers may need to be used several times a day as their effect wanes after a while. The most widely used short-acting bronchodilator is salbutamol, a beta2 agonist which works by relaxing the smooth muscles in the airway walls.
• Preventers: these medications are usually steroids (corticosteroids rather than anabolic steroids) and work by decreasing the inflammatory response in the airways. They may come in a brown or beige inhaler device and their effect is slower than that of relievers but lasts longer. As a result, they are usually used twice a day.

The dose of steroids in inhalers is low and delivered directly to the desired site of action.