F.D.A. Warns Against ‘Microdosing’ Mushroom Chocolate Bars

At least eight people in four states have fallen ill after eating Diamond Shruumz-brand Microdosing Chocolate Bars, including several who had seizures or lost consciousness and needed to be placed on ventilators. People also developed high blood pressure and abnormal heart rates.

The Food and Drug Administration has warned people against consuming the bars, which are sold online and in smoke shops across the country and come in flavors like birthday cake and cookies and cream.

It’s not clear why the bars might have sickened consumers. Diamond Shruumz has marketed the chocolates as “trippy little squares” and calls the chocolate a “microdose,” referring to a term for a small amount of a psychedelic. But the company has said the bars do not contain psychedelic substances, including psilocybin, the hallucinogenic drug found in so-called magic mushrooms. Instead, Diamond Shruumz says its products have “nootropic and functional mushrooms,” like Lion’s Mane, Reishi and Chaga mushrooms.

The company did not respond to multiple requests for comment.

The Food and Drug Administration and Centers for Disease Control and Prevention are working with poison control centers and state health agencies to investigate the cause of the illnesses.

“Our initial belief is that it’s something else that truly isn’t psilocybin but close enough to give that effect, which is why it’s being marketed as a microdosing edible,” said Dr. Steven Dudley, director of the Arizona Poison and Drug Information Center.

Mushroom chocolates have grown more popular in recent years, as companies capitalize on a wealth of research around — and consumer interest in — psilocybin. “There’s just this real proliferation of these kinds of products,” said Dr. Stacy Fischer, a researcher studying psilocybin at the University of Colorado School of Medicine.

There is little regulatory oversight of these chocolates, which sometimes contain psilocybin or other compounds that can induce a psychedelic effect. And most of the products are not independently tested to confirm what they contain — which makes it all but impossible for consumers to know what they’re getting in a mushroom chocolate bar.

“There’s not great quality control around some of these products to know exactly what’s in them,” said Dr. Chris Hoyte, medical director of the Rocky Mountain Poison Center, which is investigating illnesses linked to Diamond Shruumz.

“It really worries me from a public health standpoint: Trying to commercialize these with no regulation whatsoever means you might have all kinds of things being placed into these kinds of products,” Dr. Fischer said.

Some bars branded as “mushroom” chocolates may contain psilacetin, sometimes called 4-AcO-DMT, a compound that produces similar effects to psilocybin, said Dr. Mason Marks, a law professor at Harvard University and Florida State University who specializes in psychedelic regulation. The health effects of psilacetin have not been widely studied, he said.

Dr. Christopher Holstege, director of the Blue Ridge Poison Center at the University of Virginia School of Medicine, said he was concerned about the risk of contamination posed by these products because there is so little regulation of their manufacturing.

And there is no guarantee that consumers are getting the accurate dose of whatever drug is listed on a mushroom chocolate’s label, he added.

The F.D.A. has said that anyone who falls ill after eating these bars should seek medical attention and contact the national Poison Help Line at 1-800-222-1222. The agency also said that retailers should not sell or distribute the bars.