Preventer inhalers are probably your most important asthma medication, because they treat the inflammation inside your airways, and reduce the likelihood of an asthma exacerbation. 

When you have asthma, your airway walls become leaky, and harmful triggers can get through and cause swelling. Preventer medicines help to seal up your airway walls. 

This helps break the cycle of swelling and mucus production, and makes room for air to flow freely. 

Preventer medicines work slowly and it may take you up to three months of regular use (generally twice a day) to notice the full benefit of the medicine. It can be dangerous to skip a few doses or stop your preventer when you feel well, as your asthma will often get worse.

Preventer inhalers are usually brown, orange. 

Corticosteroid Preventers

Most preventer medicines are steroids, which mimic the steroid we produce naturally in our bodies every day. An enormous body of research demonstrates that they are safe and effective for long term use.

Like all drugs, there can be side effects, which are less common in moderate doses. Side effects may include a husky voice, a sore throat or fungal growth in the mouth (thrush). The risk of side effects can usually be easily minimised by using a spacer (for people who use a Metered Dose Inhaler (MDI)) and rinsing the mouth after inhaler use.

More general side effects occur infrequently. These are due to tiny amounts of the drug being absorbed into the blood stream. The liver will clean up most of this but if very high doses of inhaled steroids are used there may be some side effects which include:

  • thinning of the bones called osteoporosis
  • thinning of the skin giving rise to easy bruising
  • a reduction in the body’s ability to respond to a severe medical illness.

For children, an additional problem can be minor growth suppression. This is unlikely when moderate doses are used.

Most experts agree that the risk of poorly treated asthma is far greater than the risk of serious side effect from inhaled corticosteroids. Anyone who is concerned about possible side effects from their medication should discuss the matter with their doctor.

Non-steroidal preventer medicines can be useful in mild asthma, especially in children. An extra dose can be taken before exercise if needed to prevent cough and wheeze. They are free of most side effects, apart from throat irritation. 

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