Xanax, a strong drug used to combat anxiety, is the mystery substance that Jupiter police now say Tiger Woods told officers he had taken on top of the painkiller Vicodin when he was arrested May 29 on DUI charges, a report says.

Doctors warn that Xanax and Vicodin can be especially dangerous when mixed, hindering the body’s ability to breathe. In an August 2016 advisory, the U.S. Food and Drug Administration warned of “serious risks and deaths” from combining benzodiazepines, such as Xanax, with opioid medicines, such as Vicodin. That class of powerful narcotic medicines treats severe pain.

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At 2 a.m. on Memorial Day, Jupiter police have said, they found Woods asleep at the wheel of his damaged Mercedes-Benz on Military Trail south of Indian Creek Parkway.

Woods, who had undergone his fourth back surgery in April, said he had not had anything to drink that night but did take prescribed medications including Vicodin, police wrote in their report.

Woods said later in an official statement to reporters that he had had an “unexpected reaction” to the drugs.

When the police report first was made public, in two passages in which officers asked if Woods had taken any medication, his answer was blacked out. But a newly released version, which does not feature the redactions, reveals in both cases he said, “Xanax.”

The drug — also known as Alprazolam — treats anxiety, insomnia, and seizures, according to the Food and Drug Administration.

Woods’ Breathalyzer results came back as 0.000. His urine sample results have not been revealed.

Neither Woods’ publicist Glenn Greenspan, nor his attorney on the DUI case, Douglas Duncan, immediately responded to requests for comment.

View the full police report here at the Palm Beach Post.

Florida police release name of the “mystery drug” in Tiger Woods’ blood when he was arrested AP Photo/Seth Wenig
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