Most people are able to achieve asthma control by taking 1 or 2 puffs of a controller medicine containing an inhaled steroid (such as Flovent and Pulmicort) 1 to 2 times a day. The steroids work over time to reduce inflammation in the airways and prevent permanant damage to the lungs. In addition, many people occassionally use a bronchodilator (such as Xopenex, also known as short-acting bronchodilators), to prevent exercise-induced attacks and to relieve the symptoms of an oncoming asthma attack. (It's important to note that inhaled steroids DO NOT immediately relieve asthma symptoms. Likewise, bronchodilators DO NOT relieve inflammation in the airways.)
But for people who have severe persistent asthma, an inhaled steroid is often not enough. Yes it helps, but it doesn't bring about consistent and/or complete asthma control. These people will often benefit greatly from taking a long-acting beta agonist (such as Serevent or Foradil) in addition to the inhaled steroid.
What's a beta agonist? It's a bronchodilator that asthmatics take every 12 hours to relieve and prevent bronchospasms (tightening of the airways). These long-acting beta agonists should NOT be used for breathing emergencies.
It's possible to use 2 different inhalers and take the medicines one at a time. But you do have another option -- what is called a combination inhaler. Advair is one example; Symbicort is another. Both pair an inhaled steroid with a long-acting beta agonist (or bronchodilator).
I think it's pretty obvious that using one of the combination inhalers would be more convenient than juggling 2 different inhalers (plus your short-acting bronchodilator). That's a no-brainer. But recent research has suggested that using a combination inhaler is also safer than taking the 2 types of medicine individually.
Researchers out of Kaiser Permanente did a retrospective study (meaning they analyzed past study results) to look at the safety of asthma medications. They found that people taking Advair had lower mortality rates than people taking an inhaled steroid and a long-acting beta agonist separately.
One theory is that having the drugs combined in one device just makes it easier to follow the doctor's instructions. There is simply less margin for error. But the study failed to completely rule out other possible influencing factors, so more detailed study will be needed before we can draw any lasting conclusions.
Still, it is an interesting twist on our body of knowledge about the safety of asthma medicines, and I look forward to seeing the data validated down the line.