Two studies out of Cornell and Stanford revealed some of the dangers involved in taking asthma medications ? such as developing a tolerance that may lead to an increased risk for asthma attacks as well as an increased risk for heart attacks. Researchers suggest a conflict of interest between the scientists and the pharmaceutical companies that manufacture beta-agonists and fund scientific research. Shelley Salpeter, MD, clinical professor of medicine at Stanford University, compared results from 33 trials on the cardiac effects of beta-agonists. She concluded that "continuous use of beta-agonist drugs causes asthma patients to develop a tolerance for the drugs, making them less effective in true emergencies." Researchers also found that the use of beta-agonists has demonstrated an increased risk of heart attacks as compared with placebo. Beta-agonists increase the heart rate and decrease the essential potassium level, creating the opposite effect of the beta-blocker drugs used to decrease the risk of heart attack and congestive heart failure in patients with heart disease. Dr. Salpeter concluded, "We worry that physicians who recommend regular use of beta-agonists may actually be putting their patients at risk."