LOS ANGELES • Swimming great Michael Phelps revealed that he has battled severe anxiety and depression for much of his life, which drove him to consider suicide after his success at the 2012 Olympics.

Speaking at a mental health conference in Chicago last week, the 23-time Olympic gold medallist talked openly about his long battle with crippling depression and is encouraging others to get help like he did.

"After every Olympics, I think I fell into a major state of depression," the 32-year-old said.

The American said he reached rock bottom following the London Games where he won four gold medals and two silvers.

For four days, he remained in his room without food or sleep.

"I didn't want to be in the sport any more," he said. "I didn't want to be alive."

When he hit a low point in his depression, he said, "You do contemplate suicide."

Over the past two years, he has opened up about his struggles. He said his depression and anxiety problems have been a staple of his life for the past 17 years.

"We're supposed to be big, macho, physically strong human beings, but this is not a weakness," he said. "We are seeking and reaching for help."

The Baltimore native started swimming at the age of seven and won his first Olympic gold medal in 2004 at the Athens Games. That same year, he experienced his first "depression spell".

He said as he got older, his depression led to drug and alcohol abuse. In 2008, after winning a record eight gold medals at the Beijing Games, Phelps was photographed smoking from a bong. He has also been arrested twice for drink driving.

"It would be just me self-medicating myself, basically daily, to try to fix whatever it was that I was trying to run from," he said.

Phelps' boyhood hero, Ian Thorpe, has also battled dark demons outside the pool. The retired Australian swimmer, who broke 22 world records, wrote in his 2012 autobiography that not only did he consider suicide but he also planned ways and places to do it.

In an interview with CNN last week, Phelps said he wants to eliminate the stigma associated with mental illness.

"(Mental illness) has a stigma around it and that's something we still deal with every day," said Phelps, whose foundation offers stress management programmes.

"I think people actually finally understand it is real. People are talking about it and I think this is the only way that it can change."

He retired after the 2016 Olympics in Rio de Janeiro as the most decorated Olympian of all time with 28 medals. That year, he married Nicole Johnson and became a father to a son, Boomer.

AGENCE FRANCE-PRESSE