There are two main types of asthma medicine, relievers and preventers:

Reliever inhalers are usually blue and are used to relieve symptoms. Relievers are used on an "as needed" basis to quickly reverse bronchoconstriction. They work quickly by relaxing the muscles surrounding the narrowed airways. They are essential in treating asthma attacks and are useful in preventing exercise induced asthma. If the patient needs to use a reliever inhaler three or four times a week, they should go back to the doctor and have their symptoms reviewed so that these can be kept under control.

Reliever medicines are typically short acting ß₂ agonists (SABA) such as salbutamol or terbutaline. These drugs start to act within 5 minutes or less after inhalation and reach a peak effect within 4-6 hours.

These inhalers should only be used on a when required basis. Increasing use indicates a potential deterioration in asthma control and requires the patient's treatment to be reassessed.

Patients whose asthma symptoms are well controlled should have little or no need to use their SABA inhaler.

The LABA formoterol has a rapid onset of action and is licensed for symptomatic relief of asthma symptoms. Formoterol should only be used by patients who regularly use an inhaled corticosteroid as there is evidence that use of a LABA without an ICS is associated with increased asthma mortality.

Preventers usually come in brown, red, purple or orange inhalers. Preventers are used daily on a long term basis to keep asthma symptoms under control. They work by controlling the swelling and inflammation in the airways, stopping them from being so sensitive and reducing the risk of severe attacks. Their effect builds up over a period of time so they need to be used every day, usually morning and evening, even when the patient feels well. Most preventers contain a steroid medicine. It is important to reassure the patient that they are NOT the same as anabolic steroids used to enhance athletic performance.

Inhaled corticosteroids (ICS) are the most effective drugs to control asthma symptoms in adults and children.

ICS are prescribed from step 2 of the BTS guidelines. ICS should be prescribed for any patient who has:

• used a SABA three or more times a week.
• had symptoms three or more times a week.
• experienced nocturnal symptoms on more than one night a week.
• suffered an exacerbation in the last two years.

Corticosteroids used in the treatment of asthma include beclometasone, budesonide, fluticasone, mometasone and ciclesonide. ICS differ in their potencies and bioavailability but most patients will benefit from daily doses equivalent to 400microgram of beclometasone dipropionate. Increasing the dose above this level has limited benefits but significantly increases the risk of side effects.

There is also a specific issue with regard to differences in bioavailability of beclometasone preparations. Qvar® (beclometasone dipropionate) is not interchangeable with other inhalers; due to the nature of the formulation, Qvar is more potent than other beclometasone inhalers. Beclometasone inhalers should therefore be prescribed by brand to avoid any confusion.