Many doctors feel ill-equipped to counsel their patients about the potential medical uses of marijuana, USA Today reports. Some states are establishing physician training programs to address marijuana’s health effects. Currently, 25 states and the District of Columbia allow medical marijuana. Some states are starting to require doctors to take continuing medical education classes that discuss how marijuana interacts with other medications and affects the nervous system. In most states that allow medical marijuana, patients with qualifying medical conditions must receive certification from a doctor. Many doctors say that without knowing the health effects of marijuana, they are uncomfortable writing a certification. Many also say they are uneasy about dealing with medical marijuana because the drug remains illegal under federal law.