Tiger Woods told arresting officers he'd taken Xanax the night he was pulled over for DUI ... which has only now been revealed by an unredacted copy of the police report.

In previous police docs, Tiger had copped to 4 other meds -- Solarex, Vicodin, Torix and Vioxx ... which he said he hadn't taken this year. There was no mention of Xanax.

However, the new unredacted document -- first obtained by Golf Channel -- makes it clear ... when the officer asked Tiger if he'd taken any medication he stated Xanax.

It's unclear why that drug was initially concealed in the report, but it helps support Tiger's original statement in which he said he'd had "an unexpected reaction to prescribed medications."

There was no clear danger in combining the 4 drugs originally listed -- however, Vicodin and Xanax is a whole different story. The FDA warns combining Xanax with opiods can result in "profound sedation, respiratory depression, coma and death."

TOTALLY OUT OF IT