There is a risk that taking psilocybin can trigger psychotic episodes in some people, Nemeroff said.

Risk appears to be higher in people who have a family history of conditions associated with psychosis such as schizophrenia or bipolar disorder. Other people who may be at higher risk for a psychotic breakdown from magic mushrooms or psilocybin include those who have a history of substance abuse, people who are mentally unstable, and anyone having suicidal thoughts, Nemeroff said.

Importantly, these types of episodes can last far beyond when the drug is actually in the body. “When a psychotic episode is triggered, it’s not about the effects of the drug at all,” he said. “It takes on a life of its own.”

Josh Woolley, an associate professor in the department of psychiatry and behavioral sciences at the University of California at San Francisco, said if the off-duty pilot took mushrooms 48 hours before the incident on the plane, “he very likely did not have any psilocybin or other active ingredients in his body at the time … but that doesn’t mean that his experience was not related to his mushroom use.”

Researchers who study psilocybin generally screen out people who have family or personal history of psychosis, schizophrenia, mania and bipolar disorder, and because of that, Barrett said, they don’t tend to see any prolonged negative effects from the drug.