Jolanta Piszczek is a pharmacist and Certified Asthma Educator (CAE).
Asthma medications are commonly divided into two groups: the “relievers” and the “controllers”. Many people will use both –“controllers” to prevent asthma symptoms from occurring and “relievers” to treat occasional asthma symptoms. These drugs can come in a variety of forms. (See Devices  section for tips on how to use the different inhalers.)
Reliever medications are also called “rescue inhalers” or “bronchodilators”. They are used to quickly alleviate symptoms such as cough, shortness of breath, wheezing and chest tightness. They do so by relaxing the muscle that constricts the airway, allowing it to open and receive more air. They do not, however, reduce inflammation and mucus in the lungs.
Relievers play a crucial role in asthma treatment because exacerbations can occur at any time, even if you take a controller medication to prevent symptoms. Some people will also use a reliever to open the airway right before exercise.
Relievers usually work within 5 to 10 minutes and last anywhere from 4 to 12 hours. Based on their duration of action, relievers are often grouped into two categories: short-acting and long-acting.
Short-acting relievers usually last about 4 to 6 hours, and therefore they are often prescribed “every 4 to 6 hours as needed”.
Examples of short-acting relievers (in Canada) are:
Ventolin HFA (Salbutamol)
Apo-Salvent CFC Free (Salbutamol)
Long-acting bronchodilators can only be called “relievers” if they work fast enough to be able to open the airway during an exacerbation. Their action in the body lasts about 12 hours, and they are often prescribed “twice daily as needed.”
Quick and long-acting beta agonists are:
Serevent (Salmeterol) is a long-acting beta-agonist that is not used as a reliever because it starts to work after about 30 minutes. It can be used to keep the airway open for 12 hours, and although it can be used alone for emphysema or CODP, as an asthma treatment it is combined with a controller medication, fluticasone, in an inhaler called Advair.
Bronchodilators are well tolerated when used within their prescribed doses. They can sometimes cause shakiness or tremor, a fast heart beat, nervousness or headaches.
Next Page: Controllers
Controllers prevent asthma symptoms as they treat the inflammation inside the lungs. Controller medications need to be taken every day even if you do not have asthma symptoms. Having your asthma under control means that the medication is doing its job, and shortly after a controller is stopped, symptoms tend to return.
Inhaled corticosteroids (ICS) block the immune cells in the lungs from creating unnecessary mucus and inflammation when exposed to asthma triggers. These medications do not work right away; it can sometimes take 1 to 2 weeks before their effect is felt, and that is why they cannot be used during a sudden asthma attack.
If your symptoms worsen, your Asthma Action Plan can guide you through adjusting your controller medication to keep inflammation in check.
Side effects of inhaled corticosteroids can include voice hoarseness, sore throat and a throat yeast infection called thrush. These side effects can be prevented or minimized by using the correct inhaler technique and, if you’re using a meter-dose inhaler, to use a spacer. 
Spacers help deposit the medication in the lungs instead of in the throat and mouth. Rinsing out your mouth with water after using your inhaled corticosteroids will also help reduce these side effects.
Examples of inhaled corticosteroids:
QVAR (Beclamethasone dipropionate)
Leukotriene Receptor Antagonists (LTRAs)
Leukotrienes are immune messengers that are involved in inflammations. The LTRAs are oral medications that block the action of leukotrienes in the airway and are used to prevent inflammation from occurring in the lungs and causing asthma symptoms. LTRAs are not steroids, and can be used alone or with inhaled corticosteroids to control asthma. They are sometimes called “steroid sparing” because your doctor might add a LTRA instead of increasing the dose of your inhaled corticosteroid.
Accolate (Zafirlukast )
LTRAs are generally well tolerated, but side effects can include headache or nausea.
Next Page: Oral Corticosteroids
Oral corticosteroids are usually reserved for severe asthma symptoms and are usually only used short term. The goal of good asthma control is to quickly recognize that your symptoms are worsening and adjusting your controller medications according to your asthma action plan. This way, they should never progress to the point where oral steroids are required.
Oral corticosteroids can have serious side effects if used too often or for a long time. However, if asthma symptoms are very severe, the benefits of using them outweigh the risks.
Oral corticosteroids include:
Deltasone, Apo-Prednisone, Novo-Prednisone (prednisone)
With long-term use, oral corticosteroids can cause side effects that include stomach irritation, water retention, increased appetite and weight gain, growth suppression in children and fractures.