If you have asthma and feel that your steroid medication just doesn’t help you much, there’s a bit of good news for you. Researchers seem to have discovered why steroids don’t do the trick for so many asthma sufferers.

The research was conducted at the Airway Clinical Research Center of the University of California, San Francisco, and published in American Journal of Respiratory and Critical Care Medicine. To find out more, I called the senior author of the study, center director John V. Fahy, MD.


Over a period of six weeks, Dr. Fahy and his colleagues analyzed sputum (mucus from the lungs) from 995 people with mild-to-moderate persistent asthma. Researchers were looking for the presence of white blood cells called eosinophils. Eosinophils are immune cells that release toxins to kill off parasites, but in some asthmatics they fire off toxins inappropriately, causing inflammation. For years, scientists had assumed that asthma was caused by the collection of these cells in the airways, and so asthma treatments have focused on controlling them. But since not everyone responds to certain asthma treatments in the same way, Dr. Fahy and his colleagues suspected that not all asthmatics have these types of cells in their sputum.

Here’s what they discovered…

  • 22% of the asthma patients persistently had eosinophils in their sputum on every occasion and thus were categorized as having persistent eosinophilia.
  • 31% of subjects had eosinophils in their sputum on at least one occasion and were categorized as having intermittent eosinophilia.
  • But a whopping 47%—nearly half!—of subjects had no eosinophils on any occasion and were categorized as having persistent non-eosinophilia.

So what does this mean for asthma patients? Well, if you have the type with no eosinophils (and there seems to be about a 50-50 chance of that), it means that one or more of the treatments that you have likely been using for years may not be working that well. And that is what the researchers confirmed next…


Dr. Fahy noted that treatment for asthma is typically two-pronged. The first—and mainstay—treatment is to reduce inflammation caused by eosinophils through the long-term use of oral or inhaled corticosteroids. The second approach generally consists of a bronchodilator with albuterol (a beta agonist drug) that relaxes bronchial muscles and provides on-the-spot symptom relief.

So, during “part two” of the study, Dr. Fahy and his colleagues tested one measure of medication efficacy—lung function (a measure of how much air your lungs can hold and how quickly you can move air in and out of your lungs). They found that the corticosteroid medications improved lung function only in subjects with persistent or intermittent eosinophilia, and there was no effect in patients with persistent non-eosinpohilia. In contrast, the albuterol bronchodilator improved lung function in all three types of patients.

Dr. Fahy told me that in the past, it was thought that some genetic defect was the reason some asthmatics responded poorly to corticosteroid medication. And that may be true for some, but for most, the reason now seems to be that they have no eosinophils in their lungs.


So does this mean that all asthmatics should get tested to see if they have eosinophils in their airways—and if they don’t, then they should stop taking corticosteroids? Unfortunately, the answer to both questions is no—because right now, identifying whether you have eosinophilia or not won’t do you any good.

Corticosteroids may not help those with non-eosinophilia improve their lung function, specifically, but according to Dr. Fahy, they are still the best treatment currently available for asthma and they do help those particular asthmatics at least a little bit in other ways. For example, studies by other researchers have shown that these steroids can reduce the rate of asthma attacks, lessen swelling in the airways and decrease the lungs’ responses to irritants.

So all asthmatics on corticosteroids should continue taking them unless their doctors advise otherwise. The good news is that knowing why steroids aren’t as effective as they could be is likely to help scientists develop new treatments that are more effective.