Cate Campbell will leave Rio with some extra weight in her baggage and on her mind — with the "greatest choke in history" accompanying the Australian swimmer's gold and silver relay medals.

Campbell, the 100-meter freestyle world-record holder, arrived as a top tip for individual gold yet finished sixth in her strongest event.

On Saturday, in the 50m freestyle, she finished fifth.

"The world got to witness possibly the greatest choke in Olympic history a couple of nights ago," Campbell told Australia's Seven Network.

Speaking to reporters, the older of the two Campbell sisters competing in Rio hinted at a possible injury but said now was not the time to talk about it.

"I'm not here to make excuses. Everyone has injuries and setbacks and I'm not about to put anything in print just now," she said.

"I want my results to stand for themselves and I want to be able to stand and take responsibility for my actions. There may be a few things coming out a little bit later but that is absolutely not relevant at the moment."

Campbell said it had been a tough week in the Olympic pool, where Australia's wait for an individual women's gold continued unsatisfied despite 4x100m freestyle success.

While Mack Horton and Kyle Chalmers won 400 and 100 freestyle golds, respectively, the women failed to end a drought that has now extended to eight years.

"It's been a tough week, there is no denying," said Campbell, after anchoring the Australian women to a final silver medal in the 4x100m medley relay with a last leg that pipped Denmark by just 0.01 seconds.

"But I'm very proud of that swim. I executed exactly how I was supposed to do it two nights ago and came away with a very different result."