Salmeterol or formoterol from an inhaler as an extra treatment to prevent asthma symptoms
BMJ Group Medical Reference
This information is for parents of a child who has asthma. It tells you about taking salmeterol or formoterol from an inhaler, as an extra treatment to prevent asthma symptoms. It is based on the best and most up-to-date research.
Do they work?
Yes. Research shows that using a salmeterol or formoterol inhaler as well as a steroid inhaler is likely to help children control their asthma.
Salmeterol and formoterol aren't usually used on their own to prevent or control asthma symptoms. They tend to be used as an extra treatment for children who are already using a steroid inhaler.   That's because salmeterol and formoterol can actually make asthma symptoms worse if they're used on their own. 
What are they?
Salmeterol and formoterol inhalers help relax the muscles in the airways. This opens them up and makes it easier for your child to breathe. Your child's doctor might suggest these treatments if a steroid inhaler on its own doesn't keep your child's asthma under control. 
Salmeterol and formoterol are long-acting drugs used to prevent asthma symptoms. They take about half an hour to work, and the effects last for about 12 hours. Your child shouldn't use these drugs to treat an asthma attack. Your child should have a quick-relief inhaler to use when he or she gets symptoms.
Your doctor may call salmeterol or formoterol bronchodilators because they dilate (open up) the bronchial tubes (airways). You may also hear these drugs called long-acting beta-2 agonists.
The brand name for salmeterol is Serevent. Brand names for formoterol include Foradil and Oxis. Your child takes them using an inhaler. But these drugs shouldn't be used on their own to help control asthma symptoms.   Children should carry on taking their inhaled steroids.
If these drugs don't seem to be working as well as they used to, your child should see their doctor or practice nurse.  It could be a sign that their asthma is getting worse.
How can they help?
If a steroid inhaler is not controlling your child's asthma, adding a salmeterol or formoterol inhaler is likely to help. Research shows that these medicines may help your child breathe better.  Studies also suggest that using a salmeterol or formoterol inhaler in addition to a steroid inhaler can help children control their asthma symptoms better than just increasing the dose of their steroid inhaler.