A growing number of Americans may be having serious reactions after taking phenibut -- an unapproved anxiety drug sold in some dietary supplements.
That's the finding of a new study looking at calls to U.S. poison control centers. The numbers are not huge: Between 2009 and 2019, there were 1,320 calls related to phenibut.
But there was a sharp rise beginning in 2015, researchers found -- going from a handful of calls each year to between 300 and 400 in 2018 and 2019.
More worrisome, the effects were sometimes life-threatening or fatal, said researcher Janessa Graves, an associate professor at Washington State University.
Overall, 80 people fell into comas and three died. Often, they had taken other substances as well. But even in cases where phenibut was used alone, 10% resulted in serious effects -- including one death.
"This is reason for concern," Graves said. "[Phenibut] is easily accessible, and it may be becoming more popular."
The findings were published Sept. 4 in the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Originally developed in the Soviet Union in the 1960s, phenibut was given to cosmonauts, with the aim of combating anxiety and insomnia. It has never been an approved drug in the United States, but it is present in some dietary supplements marketed for enhancing mood and brain power.
The U.S. Food and Drug Administration has ruled phenibut is not a dietary ingredient and cannot be listed as such in dietary supplements. But phenibut supplements are widely available online, Graves noted.
There have also been reports of people abusing the drug for euphoric effects. A recent study of Minnesota poison centers found that in nearly half of calls related to phenibut, the person had used it with "abuse as the reason."
The drug is similar to a brain chemical called GABA, which has a calming effect on the central nervous system. That can also cause side effects like sedation, reduced levels of consciousness and depressed breathing.
Previous research has uncovered signs that phenibut use is trending upward in the United States, Graves said. So her team tried to get a bigger picture, by analyzing a national database on calls to poison control centers.
From 2009 to 2014, they found there was a small number of calls each year related to "phenygam" or 4-amino-3-phenylbutyric acid -- alternative names for phenibut.
Starting in 2015, poison control centers were able to use the term "phenibut." After that, there was a steady, steep rise in calls related to the drug.
It's not clear how much of that could be related to rising popularity, Graves said.
Based on internet search trends, public interest in phenibut has remained fairly stable in the past several years, said Pat Aussem, of the nonprofit Partnership to End Addiction.
"That said," she added, "the sharp rise in calls to poison control centers is concerning, and may be attributable to people searching for and using anti-anxiety supplements without knowing their safety profiles."
Consumers should not assume that dietary supplements are "safe," stressed Aussem, who was not involved in the study.
She said phenibut would be particularly dangerous in combination with other substances that depress the central nervous system -- including alcohol, opioids or benzodiazepines, like Xanax or Ativan.
In this study, 40% of adults and 30% of people under age 18 had used phenibut with other substances.
The findings highlight a bigger issue, according to Dr. Peter Lurie, president of the Center for Science in the Public Interest (CSPI), a consumer advocacy group.
In the United States, dietary supplements are largely unregulated, Lurie said, and the FDA has limited resources to take action against companies that put unapproved drugs into supplements -- or make unproven health claims.
The CSPI recently urged the FDA to take stronger steps against manufacturers and stores that sell supplements with an unapproved antidepressant called tianeptine.
The FDA has sent warning letters to a number of U.S. companies that market tianeptine or phenibut supplements. But the products are still readily available.
One of the concerns, Lurie said, is that consumers will be lured away from therapies -- medication or not -- that are proven to help anxiety and depression.
Graves and Aussem made the same point.
"In this age of COVID-19," Aussem said, "many people are trying to cope with anxiety and may wish to find a 'natural' product to alleviate their symptoms."
But, she said, "talking to a health care provider about their concerns is the safest approach."
The U.S. Food and Drug Administration has more on dietary supplements.