The study, published in The Journal of the American Medical Association, found asthmatics who took low-dose medication as a daily routine did no better than those who turned to their inhalers only when they have symptoms.
Senior author Dr. Homer A. Boushey of the University of California, San Francisco, said the findings challenge national and international guidelines that have been in place for 20 years. These recommendations said if a person's asthma was mild but persistent, he or she should take an inhaled steroid every day to suppress airway inflammation and reduce the risk of exacerbations.
"Daily treatment with an inhaled corticosteroid has long been believed to be the best treatment for mild persistent asthma, but it is not followed by the majority of patients,'' Boushey said in a statement.
Altogether, 342 adults with mild to moderate, persistent asthma took part in the study over nine months during the period of 2007 to 2010. All were diagnosed by physicians and all had either reversible airflow limitation or airway hyperresponsiveness.
The researchers found the frequency of flare-ups or exacerbations of asthma, symptom severity and pulmonary function did not differ among the treatment groups.