Apprentice Emma Ljung will need a medical clearance before she takes her mounts at Eagle Farm with stewards concerned about her health.
Ljung, who has a full book of eight rides on Saturday, was treated for heat stroke at Ipswich races last Saturday.
She was cleared to ride at Doomben on Wednesday but after riding Golfing in the fifth race she was again stood down by stewards.
Senior steward Martin Knibbs, who presided over the Doomben meeting, said his panel wanted Ljung to see Racing Queensland doctor Jack See before she rode again.
“We are worried about Emma’s health. She is a promising rider and we don’t want her to be a danger to herself or other riders if there is something wrong,” Knibbs said.