Preventer medicines make the airways less sensitive, reduce redness and swelling and help to dry up mucus. They are the mainstay of asthma treatment because they treat the underlying cause of the symptoms. Preventers need to be taken every day to prevent symptoms and reduce the likelihood of asthma attacks. It may take two-four weeks before they reach their full effect, and occasionally up to 12 weeks.

Best practice guidelines suggest a medical professional prescribe a preventer medicine for you if:

  • you have had asthma symptoms more than once in the last month,
  • you have woken because of symptoms in the last month,
  • you have had a flare-up in the last year,
  • you have ever been admitted to an intensive care unit due to an acute asthma episode

In children, preventers are usually prescribed for those with

  • frequent and persistent symptoms,
  • When moderate or severe flare ups happen more than once per year  
  • when sleep and play is disrupted by asthma, and
  • when the symptoms are brought on by a number of triggers




These inhalers are the most common preventers. They all contain medicine called corticosteroid, delivered by an inhaler device. They can help airway cells repair and return to normal by reducing airway inflammation, sensitivity and reducing excess mucus. The great advantage of these medicines is that they are inhaled and therefore work only in the lungs, precisely where the inflammation occurs.

Possible side effects include sore throat, hoarse voice and/or oral thrush.

These may be reduced by using a spacer if your preventer is in a ‘puffer’. Rinsing, gargling and spitting after each dose is also important and effective at reducing side effects.

Combination Preventer medicines



Fluticasone + Salmeterol Cipla*



These inhalers all contain two medicines within the one inhaler, a preventer like and a long-acting reliever. Combination preventers reduce inflammation, sensitivity and excess mucus, as well as relax tight airway muscles. 

Possible side effects include sore throat, hoarse voice, oral thrush, shakes, rapid heartbeat and/or headaches. 

These may be reduced by using a spacer if your preventer is in a ‘puffer’. Rinsing, gargling and spitting after each dose is also important and effective at reducing side effects

Other preventer medications

Montelukast & Singulair

These non-steroid preventer tablets are often used to help exercise-related asthma, and are more commonly used as the main choice preventer in children. Some brand names include Singulair, Respikast, T Lukast, Lukair, Montair. 

Possible side effects are uncommon but may include muscle or joint pain, gastrointestinal disturbances, headache and/or psychiatric effects such as agitation, sleep disturbance and depression. Montelukast is usually commenced as a trial prescription and is recommended to be reviewed after four-six weeks of starting.

In an April 2018 safety review, Australia’s Therapeutic Goods Administration concluded there was an association between Montelukast and psychiatric side effects (such as agitation, sleep disturbances and depression) including, in rare cases, suicidal thinking and behaviour. 

These side effects are rare. It is usually a very safe preventer medication for children and teens with asthma. Overall it is a useful first line treatment for mild to moderate asthma.

We advise parents and carers to be aware of the potential side effects, and to closely monitor children and teenagers taking Montelukast. If you have any concerns speak to your doctor or read more about the side effects of Montelukast on the Department of Health, Therapeutic Goods Administration website.



These are non-steroid preventer inhalers that work by reducing histamine (which promotes inflammation) in the airways. They are most often used in mild allergic and exercise-related asthma. They are quite powdery and can block the inhaler, so it is very important to wash the plastic casing of the inhaler frequently to make sure you are getting the full dose.

Side effects are rare, but may include headache, throat irritation, nausea and cough. About 20 per cent of people find Tilade has an unpleasant taste.