Many people were surprised when Denver and ­Oakland decriminalized “magic mushrooms,” which contain the naturally occurring hallucinogen psilocybin. But mushrooms containing ­psilocybin have been used sacramentally and recreationally for hundreds of years. They have not been shown to be chemically addictive, and preliminary studies suggest that they could be useful for treating anxiety, depression and addiction to alcohol and tobacco. Example: In a 2016 Johns Hopkins University study, two doses of psilocybin given five weeks apart significantly decreased anxiety and depression in cancer patients—and for six months afterward. 

Even though laws have changed ­locally, it will be years before mushrooms are approved for use in medical treatments in the US. Until then, they likely would be obtained from unregulated suppliers, which creates possible risks…

Psilocybin can trigger psychotic ­episodes in people predisposed to certain psychiatric disorders. In controlled settings, medical personnel would screen for these disorders. 

Psilocybin’s hallucinogenic effects could cause unintentionally dangerous behavior, such as walking into traffic. Effects can last for four to six hours after consumption. In a medical setting, patients would be closely monitored. 

Magic mushrooms can look a lot like other wild mushrooms that contain dangerous toxins—a supplier could provide the wrong ones. 

Very rarely, some people could ­experience long-lasting perceptual disturbances. 

The wisest option is to not use magic mushrooms medically for now. Or seek out approved clinical trials at ClinicalTrials.gov. The underground marketplace is uncontrolled. The data on regular usage and interactions with other drugs and conditions are lacking. They show promise and generally are nontoxic, but more research is needed.­