What Is the Evidence of Marijuana as Medicine?

Marijuana as medicine is a controversial and often distorted topic. Medical marijuana in the United States has bypassed the standard process of scientific investigation that is required to determine approval of medicine and has created a political controversy among the American public and in the scientific community. This chapter discusses the science where the heart of the controversy lays—at the question of whether marijuana’s potential benefits outweigh its potential harms. We review the history of marijuana’s development as a medicine and summarize the impacts of medical marijuana laws in the United States and the challenges associated with doing so. We conclude that some benefits of marijuana’s core elements—tetrahydrocannabinol and cannabidiol—are supported by a handful of controlled clinical trials for a very limited number of health problems.