A VISITING family says their Cairns holiday was ruined when 12-year-old Mitchell Macdonald stepped on a used condom left in their motel room.

Grandmother Jannelle Summers stayed at Woree's Coolabah Motel on Mulgrave Rd with her grandsons Mitchell and Mathew, 10 and her daughter Stacey Macdonald on Saturday.

But their family holiday turned into a nightmare when Mitchell stepped off the room's bed on to a used condom that had been left by previous guests.

While the motel managers deny the incident took place, Ms Summers said she now feared for Mitchell's health.

"My daughter Stacey and I just looked at each other in disgust," she said.

"Stacey grabbed Mitchell and washed his foot, she was making sure he didn't have any open cuts on him."

The two boys had moved the bed while horsing around but when Mitchell stepped off it he put his bare foot on the condom.

"He hardly slept that night he kept thinking he was dirty," she said.

The family also claim they found mould in the bathroom and a layer of dust on the floor.

They have since launched a complaint against the motel to Cairns City Council and the Department of Fair Trade.

Speaking from Townsville mother Tammy Macdonald, who was not at the motel at the time, said the incident had affected her son mentally.

"It made me sick to my stomach when mum told me, his self-esteem is affected by this," she said.

"He thinks he's got AIDS."

But the motel's managers say the claims are untrue.

"The health inspectors were here just the other week, how come they didn't find anything wrong with the place?" Coolabah's manager, who refused to be named, told The Cairns Post.

"She was just after her money back, I never saw this offending condom.

"This whole thing is a little bit ridiculous, when I went in the room it was not there."

The manager said he would press legal action against Ms Summers if she proceeded with her claims against his establishment.

Cairns City Council have confirmed their health inspectors would have spoken to the motel after the incident.

The family stopped in Cairns on their return from Townsville to Alice Springs by have vowed never to return.