FORT LAUDERDALE, Fla. -- Ryan Lochte, the longtime Olympic swimmer, has accepted his 14-month suspension after he shared an Instagram photo of him using an IV to inject vitamins, the U.S. Anti-Doping Agency (USADA) announced Monday.

Lochte, 33, cannot compete as planned in the national championships that start this week in California. The eight-time Olympic gold medalist will also be ineligible for other top meets, including the Pan Pacific Championships later this year and next year's world championships. "This is devastating," Lochte said.

He did not take a banned substance, but he got an intravenous injection of vitamins in May -- and since it exceeded 100 milliliters, no matter what was involved, he broke anti-doping rules. The ban, retroactive to May 24 and announced Monday by USADA, is his second in less than two years following his 10-month suspension for his behavior during a drunken incident that created widespread scorn at the 2016 Rio de Janeiro Olympics.

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"A rule is a rule and I accept that there is a technical violation," Lochte said. "I am hopeful other athletes will learn from my mistake and be mindful of this rule, as well as others."

Ryan Lochte at the 2016 Summer Olympics in Rio de Janeiro, Brazil. AP

Lochte said he took the IV because both his wife and his son were ill and had recently visited hospitals, and that he didn't want to get sick as well. He said the IV contained B-12 and other vitamins that could be purchased at any pharmacy.

He and his wife both got IV infusions in Gainesville, Florida, he said, to bolster their immune systems.

"I've been swimming my whole life and I've been monitored by USADA for my entire competitive career," Lochte said. "I have never taken a prohibited substance. I have never attempted to gain any advantage over my competition by putting anything illegal in my body. I would never do that."

In Brazil, he there were questions about his version of what happened. This time, he revealed what happened -- obviously unaware of the ramifications it would bring.

Lochte's violation came to light when he posted the photo of him getting the IV on his social media accounts. That triggered the USADA investigation, one that Lochte "fully cooperated" with according to U.S. officials.

"Lochte received an intravenous infusion of permitted substances at an infusion clinic," the USADA announcement of the suspension said. Under most circumstances, athletes cannot receive IVs unless related to a hospitalization or when allowed under the terms of a USADA-approved exemption -- and Lochte fell into neither of those categories.

Ryan Lochte, center, celebrate winning gold in the Men's 4 x 200m Freestyle Relay Final at the 2016 Olympic Games in Rio de Janeiro, Brazil. Getty

Suspensions for use of an IV are extremely rare: The USADA database shows only two other athletes being sanctioned for using such a method, one of them getting a six-month suspension and the other a 14-month ban, just like Lochte. That same database shows that before Monday, no other U.S. swimmer in the last 10 years, for any reason including actual positive tests, had been suspended for more than one year by USADA.

This week could have been a significant step forward for Lochte, who was entered in four events at the U.S. championships at Irvine, California, and was preparing to compete in what would have been his biggest competition since the Rio Games. Lochte said that he and three other U.S. Olympic swimmers there were robbed at gunpoint at a gas station, a story that quickly unraveled.

The investigation in Brazil is continuing, and Lochte said it's "concerning" to him that a court there recently decided that he could still face prosecution for filing a false report.

Lochte was not only suspended 10 months for that debacle, but also forfeited $100,000 in Olympic medal bonus money and was banned from competing in last year's national and world championships.

And now, he's back in hot water. USADA agreed to start the 14-month clock on May 24, the day that he posted the photo that no longer can be found on his Instagram page. He reiterated Monday that he wants to compete in the 2020 Tokyo Olympics, though those hopes would seem to be in at least some doubt now.

"I should know better," Lochte said.

Lochte spent much of his career portraying a party-boy image, while his wildly successful exploits in the pool -- six Olympic golds, 36 world championship gold medals, no fewer than four world records -- were always overshadowed by 28-time Olympic medalist and 23-time Olympic champion Michael Phelps.

After Rio, Lochte was dropped by at least four major sponsors including Speedo USA and Ralph Lauren, though he has added some endorsement deals since. He was also apparently targeted by two men wearing t-shirts bearing an anti-Lochte message rushed the stage while he was competing on ABC's "Dancing with the Stars."

Lochte returned to competition last year, most notably winning the 200-meter individual medley at the U.S. Open. He also has become a father and a husband since Rio -- he married former Playboy model Kayla Rae Reid in January, seven months after their son was born.

Lochte will turn 36 during the Tokyo Games. He won Olympic gold in 2004, 2008, 2012 and 2016, and if he found a way to win another in Tokyo he would be the oldest Olympic swimming champion.

"I have goals that I want to accomplish in 2020," Lochte said. "If anything this is going to add more fuel to my fire."