Five-time Olympic gold medallist Kaylee McKeown says she is "gutted" after being forced to withdraw from the Commonwealth Games due to glandular fever.

McKeown's decision comes after she struggled with fatigue, shortness of breath and a loss of appetite for several months.

In addition to the Commonwealth Games, McKeown will also be sidelined for the Pan Pacific Championships in California.

"I am gutted to medically withdraw. What I thought a few months ago was the flu has turned out to be my body fighting glandular fever," she said.

"I was sick going into trials, and I just have not got better, and I am worried about pushing myself so hard that I end up with chronic fatigue.

"It was a hard decision to make, but it was the right one."

Swimming Australia will now take a contingent of 59 athletes to Glasgow for the Games.

"At this point in time, Kaylee's health is the most important thing," said Swimming Australia's Olympic head coach, Rohan Taylor.

"We all know how fierce and competitive she is, and she showed that by performing the way she did at trials.

"Kaylee is a once-in-a-generation athlete; she is what we call a racer.

"We are going to miss her … not just in the pool, but out of the pool with her experience and leadership, but I personally feel, respect and support her decision to prioritise health.

"I know after trials she significantly modified her training program to the point of no high-intensity work and she just didn't improve.

"We can't wait to see her well again and back in the water competing."

McKeown starred at the last Commonwealth Games in Birmingham in 2022, winning six medals, including four golds.