Tiger Woods says an unexpected reaction to prescription medicine led to his arrest on a DUI charge in Florida.

Woods spent nearly four hours in the Palm Beach County Jail after being arrested early Monday on suspicion of DUI.

The 14-time major champion says in a statement that alcohol wasn't involved. Woods says he didn't realize the mix of medications affected him that strongly.

He also says he understands the severity of what he did and takes full responsibility.

Woods had a fourth back surgery on April 20. He wrote in an update on his website last Wednesday that the fusion surgery gave him instant relief from pain and that he hasn't felt this good in years.