Olympian Emma Jackson says mental and physical exhaustion is behind her decision to withdraw from Australia's team for next month's triathlon world championship final in New Zealand.

The 21-year-old, who made her Olympic debut at the London Games in August where she finished eighth, says she's got nothing left after returning home and won't compete in the ITU series finale in Auckland on October 17.

"I loved the Olympics and everything about it and I have certainly got the bug to dedicate the next four years of my life to making the team for Rio," said Jackson, who finished fourth in last year's ITU world championships.

"But for now it's time for a break, time for a holiday. I just have to have a rest and a break from training.

"I have tried to hang on over the past two weeks to get myself ready for Auckland and to compete for Australia, but I rang high-performance manager Michael Flynn this week and told him I had nothing in the tank and it was time to recharge the batteries.

"One of the toughest things an athlete ever has to do is to withdraw from an Australian team but as hard as I trained it just wasn't happening and I didn't want to go to Auckland and let the team down and let myself down."

Jackson will return to training in November, meaning she'll miss the Nepean Triathlon in Sydney and the Noosa Triathlon in Queensland as well as the world championship decider.

"I love triathlon training and racing and have never had these feelings before so I believe it is a sign that I need a few weeks off to relax and recover from the long year," she said.

"I think the Olympics and the whole selection process involved with it has affected me more then I ever thought it would."

Jackson had already opted out of this weekend's second-last round of the world championship series in Yokohama, Japan.

Jackson is 18th on the standings, which are led by Australia's Erin Densham going into the Yokohama round.