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Tell Me More About Reliever Medications

There are three types of reliever (or bronchodilator) medications for asthma. They are Beta-2-Agonists, Anti-Cholinergics, and Theophyllines.


Beta-2-Agonists are distantly related to Adrenaline, but are chemically altered to have much, much less effect on the heart and the blood pressure. They are the most powerful, and most rapid, type of reliever medication. There are two main types of Beta-2-Agonists. Short-acting Beta-2-Agonists start working in about 5 minutes, reach peak effect in about 30 minutes, and finish working in about 4-6 hours. Long-acting Beta-2-Agonists start working in 5-30 minutes (depending on the drug), reach peak effect in 30-60 minutes, and keep working with maximal effect for about 12 hours.

Beta-2-Agonists are available for use in a variety of types of inhaler devices.

Common inhaled forms of short-acting Beta-2-Agonists include Ventolin® (Salbutamol) and Bricanyl® (or Terbutaline).

The long-acting Beta-2 Agonists available in Canada are SereVent® (or Salmeterol), Oxeze® (or Formoterol) and Foradil(TM) (or Formoterol). These are both available as inhalers. In Canada, Salmeterol is licensed for use in children 4 years of age and older, and Formoterol is licensed for use in children 6 years of age and older.

Combination inhalers containing long-acting beta-2 agonists combined with an inhaled steroid are also available. Long-acting beta-2 agonists can be useful for reducing asthma symptoms in people who still have symptoms despite appropriate use of an inhaled steroid. Advantages of these combination inhalers include convenience — for people requiring both medications, and, for adolescents, the combination product will prevent them from using only the long-acting bronchodilator (which provides fairly rapid symptom relief) but will ensure that they also receive an inhaled steroid, to provide an anti-inflammatory, preventer effect. There are 3 such combination inhalers licensed in Canada. Advair™ contains the inhaled steroid Flovent® (fluticasone) and the long-acting beta-2 agonist Serevent® (salmeterol). It is licensed in Canada for individuals 4 years of age and older and is available as a Diskus® dry-powder inhaler or as a metered-dose inhaler. Symbicort® contains the long-acting beta-2 agonist Oxeze® (formoterol) and the inhaled steroid Pulmicort® (budesonide). It is currently licensed for individuals 12 years and over and is available as a Turbuhaler® dry-powder inhaler. The long-acting beta-2 agonist in Symbicort® begins acting faster than the long-acting beta-2 agonist in Advair™. Zenhale® contains the inhaled steroid Asmanex® (mometasone) and also contains the long-acting beta-2 agonist formoterol. It is currently licensed for individuals 12 years of age and older and is available as a metered-dose inhaler.

Common Uses of Beta-2-Agonists

There are several common ways Short-Acting Beta-2-Agonists are used:

Inhaled Beta-2-Agonists (ie. via "puffer" or Metered-Dose Inhaler), Diskhaler®, Diskus®, Nebulizer, or Turbuhaler®) are usually given every 4-6 hours "as needed" for asthma symptoms such as coughing, wheezing, chest tightness, or trouble breathing. Beta-2-Agonist syrups can be given up to every 6 hours.If your child needs his/her Beta-2-Agonist inhaler more than every 4 hours, it is a sign of a severe asthma attack. You should discuss with your doctor — ahead of time — what to do if this happens. Many doctors will recommend that you should talk to a doctor, bring your child to a doctor, or bring your child to an emergency room, if this happens.Many doctors recommend starting a Beta-2-Agonist at the first sign of a "cold", to help prevent the muscles around the bronchial tubes from tightening up (known as bronchospasm). The Beta-2-Agonist can be stopped once the cold starts to go away, if no signs of asthma have developed.Beta-2-Agonists can be used about 10 minutes before exercise, to prevent exercise-induced asthma.There are several common ways Long-Acting Beta-2-Agonists are used:

  • People who have asthma symptoms despite optimal treatment with preventer medications may benefit from long-term, regular therapy with the combination of an inhaled steroid and a long-acting Beta-2-agonist. This can reduce symptoms, and possibly even reduce asthma attacks. In Canada, SereVent® is licensed for use in children 4 years of age and older, and Oxeze® is licensed for use in children 6 years of age and older. Regular or frequent use of a long-acting Beta-2 agonist WITHOUT an inhaled steroid is hazardous, and can increase the risk of severe asthma attacks. To avoid the situation where a patient may be prescribed a long-acting Beta-2 agonist and an inhaled steroid but forgets to take the inhaled steroid, it’s much better to get both medications combined in the SAME inhaler. Combination inhalers (containing both a long-acting Beta-2 agonist and an inhaled steroid) available in Canada include Advair™, Symbicort®, and Zenhale®. Advair™ is licensed for children 4 years and older; the other combination inhalers are licensed for people 12 years and older.
  • In older children who are endurance athletes (ie. Cross-Country Skiers), long-acting Beta-2-Agonists can be useful for prolonged protection against exercise-induced asthma. Serevent should be taken a 1/2 hour before exercise, and Oxeze or Foradil should be taken 15 minutes before exercise. Both can provide up to 12 hours of protection. People using a long-acting Beta-2 agonist also need to be receiving regular therapy with an inhaled steroid.

If you have taken a long-acting Beta-2-Agonist and are still having asthma symptoms, you can still take a short-acting Beta-2 Agonist. You should contact a doctor if the asthma symptoms are severe.Side Effects Because Beta-2-Agonists are related to adrenaline, even when they are used properly, they can cause a muscle tremor, and a mild increase in the heart rate.Very high doses can cause serious heart problems, which is why giving very frequent doses of Beta-2-Agonists should be done in a hospital setting, carefully supervised by medical staff. If your child needs his/her inhaled Beta-2-Agonist more than every 4 hours, you should carry out your doctor's plan of action. If you don't have a plan of action prepared in advance, or you have any worries about your child, you should speak to or see a doctor, or take your child to an emergency room.Regular use of long-acting Beta-2-Agonists may lead to a reduction in their ability to prevent exercise-induced asthma.Research has suggested that regular, prolonged, use of short-acting Beta-2-Agonists can lead to worsening of asthma. For this reason, current Canadian guidelines for the treatment of asthma suggest that people who need Beta-2-Agonists on an ongoing basis more than 3 times per week do not have adequate asthma control, and should receive additional therapy, using regular treatment with a controller medication, to improve their asthma control. Should this be the case with your child, you should let your doctor know, and you may should discuss potential treatment options with your doctor. Similarly, regular therapy with a long-acting Beta-2 agonist WITHOUT an inhaled steroid can lead to worsening of asthma. Long-acting Beta-2 agonists MUST be used with regular therapy with an inhaled steroid.

Anti-Cholinergic Medications

Anti-cholinergic medications relax the muscles that surround the bronchial tubes by using chemical messages which are different from the ones used by Beta-2-Agonists. One anti-cholinergic medication is presently available — Atrovent® (Ipratropium Bromide). Atrovent® is available as puffer (or Metered-Dose Inhaler) and for use in a nebulizer. Anti-cholinergic medications cause gradual, fairly mild relaxation of the muscles that surround the bronchial tubes. Because it works through messages that are different than the ones used by Beta-2-Agonists, doctors usually use anti-cholinergics together with a Beta-2-Agonist, to achieve more relaxation of tightened bronchial muscles than you could achieve with a Beta-2-Agonist by itself.

Common Uses of Anti-Cholinergics

Anti-cholinergic medication can be used to help relieve asthma attacks that usually don't get relieved enough by a Beta-2-Agonist by itself.Anti-cholinergic medication can be useful as a reliever medication in children who can't tolerate, or use, a Beta-2-Agonist.Anti-cholinergic medication can be used before exercise, to prevent exercise-induced asthma. Anti-cholinergic medication rarely cause side effects. It occasionally causes a dry throat. The medication should not be aimed towards the eyes.


Theophyllines are available as pills and syrups. They produce fairly mild relaxation of the muscles around the bronchial tubes, and cause side effects relatively commonly. For these reasons, they aren't used that often to treat asthma in children in Canada. They were used much more often, a few years ago. Recent studies suggest that low-dose theophylline may have some anti-inflammatory effects which may help inhaled steroids work better. Theophylline-type drugs available in Canada include Somophyllin-12 (Theophylline), Theo-Dur® (Theophylline), Uniphyl (Theophylline), Choledyl® (Oxtriphylline), and Phyllocontin® (Aminophylline). Theophyllines have to build up a certain level in the blood, to be effective. If the blood level is too low, the medication may not work. If the blood level is too high, serious side effects can happen. People on theophyllines should have their blood levels checked periodically by their doctors.

Common Uses of Theophyllines

In Canada, Theophyllines are used most often in severe asthmatics, who need additional medication despite treatment with other drugs.Side Effects Common side effects, which can occur even when the blood level is where it should be, include stomach aches and loss of appetite, and over-activity. Children with learning problems may have more problems learning while on Theophyllines.Many medications interact with Theophyllines. Erythromycin (a commonly-used antibiotic), for example, can increase Theophylline levels in the blood. If your child is on Theophylline and a doctor wants to prescribe a new medication for your child, you should make sure the doctor knows that the child is taking Theophylline.Extremely high blood levels can cause serious heart problems and convulsions.Tell Me About Asthma Preventer Medications  Please read our Asthma Devices Page for more information about asthma medications.

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