Dustin Johnson

Chris Condon/Getty Images

Dustin Johnson will serve a sixth-month suspension after testing positive for cocaine, Golf.com can now reveal.

Dustin Johnson is serving a six-month suspension from the PGA Tour after testing positive for cocaine, a source has told Golf.com.

According to the source, Johnson has failed three drug tests: one for marijuana in 2009 and two for cocaine, in 2012 and 2014. He was previously suspended for the 2012 failed test, but that suspension was never made public. Under the PGA Tour's drug-testing policies, the Tour is not required to announce any disciplinary actions against players who test positive for recreational drugs.

Johnson announced on Thursday that he is taking a leave of absence from professional golf, effective immediately.

"I will use this time to seek professional help for personal challenges I have faced," he said in a statement issued by his management company. "By committing the time and resources necessary to improve my mental health, physical well-being and emotional foundation, I am confident that I will be better equipped to fulfill my potential and become a consistent champion."

The PGA Tour released a curt statement wishing Johnson well and saying it looked forward to his return. When asked directly about Johnson's failed drug tests and suspension, Ty Votaw, executive vice president of the PGA Tour, said Friday that the Tour would have no further comment.

Johnson's conduct has long been a topic of conversation among close observers of the Tour. He is often seen in bars near his home in Jupiter, Fla., and is also known to have had a sexual indiscretion with at least one wife of a PGA Tour player.

The suspension means Johnson, 30, will miss the PGA Championship — the season's final major takes place next week in Louisville, Ky. — and also the PGA Tour's lucrative FedEx Cup playoff series. Johnson's agent, David Winkle of Hambric Sports Management, notified the PGA of America on Thursday that his client will also not be competing in the Ryder Cup in Scotland this September. Earlier this week, when asked if Johnson was about to be suspended by the PGA Tour, Winkle texted an SI reporter, "Don't believe everything you hear."

Winkle did not immediately respond to a request to comment on Johnson's failed drug tests and suspension.

Last year, Johnson announced his engagement to Paulina Gretzky, daughter of hockey great Wayne Gretzky. She was seen with members of her family at this year's Masters and also attended the U.S. Open. Gretzky, a model with a handful of small film credits, appeared on the May cover of Golf Digest as a fitness maven.

In 2012, Johnson played the Cadillac Championship at Doral in March and then did not play again for 11 weeks, until the Memorial in late May. Johnson said at the time that he was not playing because he hurt his back while lifting a jet ski. However, Golf.com's source says that Johnson was actually serving a suspension for failing a drug test for cocaine. The PGA Tour had no official comment at that time and Winkle denied that Johnson had been suspended.

An eight-time winner on Tour, Johnson had been enjoying one of the most successful seasons of his career, logging a win, two seconds, and seven top 10s on the way to earning more than $4.2 million. He was a near certainty to make the U.S. Ryder Cup team. Johnson's leave will make Team USA captain Tom Watson's job easier. Watson has three captain's picks for his 12-man team and, without Johnson on the squad, Patrick Reed moves up to the ninth and final automatic spot on the qualification points list. Phil Mickelson moves closer to that final berth, in 10th place. Tiger Woods remains well outside automatic qualification.

Considered one of the most lavishly talented players in the game, Johnson is without question one of the longest hitters. At the British Open two weeks ago he hit one drive that measured 405 yards. His reputation as an extraordinary driver of the golf ball makes Johnson an important endorser of TaylorMade products. Earlier this year, then TaylorMade CEO Mark King was concerned about what he was hearing about Johnson's private life but was told that there were no issues that would affect his ability to represent TaylorMade. (King is now president of Adidas North America, TaylorMade's parent company.)

In a statement TaylorMade said it supported Johnson's decision to temporarily step away from the PGA Tour. "We wish him well and look forward to his return," the company added.

Despite his wins, he is perhaps better known for the major championships he has let slip away. In 2010, he was in position to win the PGA Championship but grounded his club in a bunker on the final hole, incurring a two-stoke penalty that left him two strokes out of a playoff between Bubba Watson and eventual winner Martin Kaymer. Earlier that year, Johnson had a three-shot lead at the U.S. Open at Pebble Beach after 54 holes but shot a final-round 82 to finish eighth. And in 2011 he was in contention at the British Open at Royal St. George's before fading in the final round to finish tied second.