Oleksiak, a competitor to Sarah Sjöström, was suspended for two years for failing to report her presence three times in one year.
She denies that she has ever used banned substances.
Penny Oleksiak is the most decorated Canadian female Olympian in history with seven medals, one gold, two silver and four bronze. She won the 100-meter freestyle in Rio 2016 as a 16-year-old and finished second to Sjöström in the 100-meter butterfly.
In Paris, there were no medals for Oleksiak, who was then returning from an injury.
She says her first thought after the doping ban was to quit.
"When I first found out, part of me just wanted to put an end to it and move on. I knew this wouldn't be easy, but I've never taken the easy way in my career," she says.
Canada's progress in recent years – not least with superstar Summer McIntosh at the forefront – means that Oleksiak does not want to miss the Olympics in her new hometown of Los Angeles, where the Toronto-born swimmer lives.
I think the peak of Canadian swimming will be in LA 2028. We have so much talent and such an exciting team and I can't wait to be a part of it, she says.
