Olympic gold medallist Kyle Chalmers skipped Australia's team announcement for the swimming world championships on Sunday, citing a "massive toll" from a media storm that erupted over his rivalry with pop singer-turned-swimmer Cody Simpson.

Chalmers went into the Australian trials in Adelaide last week with no plans to swim at next month's world championships in Budapest but changed his mind after qualifying ahead of Simpson in the 100 metres butterfly.

His U-turn meant Simpson would miss out on a place on the Australian team.

Chalmers, who also hit out at speculation about his private life, said he had returned home to Port Augusta, South Australia, to look after his mental health.

"The past few days have been really challenging for me mentally and emotionally and it’s taken a massive toll on me," Chalmers wrote on social media.

"The negative media attention surrounding my decision to compete at worlds and the made-up storylines surrounding my personal life have been more than I can handle."

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Governing body Swimming Australia said it supported Chalmers' decision to skip the team announcement.

While missing out on Budapest, Simpson was confirmed in Australia's team for the Commonwealth Games in Birmingham in July-August, along with Chalmers.

Simpson said he and Chalmers, who won 100 freestyle gold at the 2016 Rio Games and silver at Tokyo last year, had already cleared the air.

"He's obviously in his right, he qualified second," Simpson told a Nine Network breakfast show on Monday.

"I was going to respect whatever decision he wanted to make.

"We're excited to go and race again over in Birmingham."