Marijuana legalization has been a controversial topic among the public, health care professionals and policymakers for decades due to the federal government’s classification of marijuana as a Schedule I drug.

The categorization—defined by the Drug Enforcement Administration (DEA) as “drugs with no currently accepted medical use and a high potential for abuse”—places marijuana under the most restrictive schedule possible. This decision limits biomedical research because scientists must gain further approval from the DEA to study the drug. This approval process is on top of needing to upgrade lab security protocols, which is time-consuming and costly.

Limited research on marijuana’s effects on the body makes it harder to gather enough evidence to allow marijuana into medical practices. If the government rescheduled marijuana to make research more accessible, medical marijuana would legally be allowed throughout the U.S. under federal law. However, the debate over rescheduling marijuana creates even more controversy.

A few studies and anecdotal evidence suggest that medical marijuana could have therapeutic benefits for many conditions, including epilepsy, chronic pain, multiple sclerosis and mental health disorders. This is largely due to interactions between the active compounds in cannabis (called cannabinoids) and the body’s endocannabinoid system.

The endocannabinoid system regulates cognitive and emotional processes in the central nervous system. Marijuana compounds activate two types of cannabinoid receptors in the body. CB1 receptors are expressed in the brain, and CB2 are expressed in organs throughout the body. These receptors can be activated by naturally generated cannabinoids inside the body (endocannabinoids) or by inhalation and consumption of products that contain the active ingredients tetrahydrocannabinol (THC) and cannabidiol (CBD). Both THC and CBD are found in marijuana; THC is what creates the “high.” CBD is considered “not impairing,” meaning it does not create a “high.”

Despite the limited evidence that may support medical marijuana, marijuana use has been widely associated with harmful effects, including lung problems in chronic users. The smoke that comes from marijuana injures the cell linings of large airways, which leads to a chronic cough, wheezing, bronchitis and more. Cannabinoids can also affect the cardiovascular system. This includes a higher resting heart rate, dilated blood vessels and making the heart pump harder.

It is sometimes difficult to tell what’s causing symptoms, however, because a significant number of marijuana users also use tobacco products. Cannabis and tobacco can cause similar side effects in the endocrine, pulmonary and cardiovascular systems. Despite the difficulty of differentiating symptoms between these two substances, a study has shown that among people who have never used tobacco, daily cannabis use was also associated with heart attack and stroke. The majority of states allow for some medical marijuana use, while nearly half have legalized recreational marijuana for adults. But, whether or not to use marijuana is a personal decision. As more states legalize marijuana, it is important to educate yourself about its risks and benefits based on scientific research.