"I believe he was hospitalised last night," Pistorius lawyer Brian Webber, told the domestic SAPA news agency. "But I think he is already at home."
The illness is, however, unlikely to delay the re-opening of the trial due on Monday with prosecution and judiciary officials saying the case would proceed as scheduled.
Nathi Mncube of the National Prosecuting Authority (NPA) told AFP the case will "most certainly" resume on Monday, he said.
After a six-week break, Pistorius is due back in court on Monday where a report on the athlete's mental state is expected to be submitted, following his month-long stint under psychiatric evaluation.
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Judge Thokozile Masipa had ordered last month that he spends 30-days under psychiatric observation to determine if he should be held criminally responsible for the Valentine's Day shooting of his girlfriend.
This was after Pistorius appeared to change his defence when he brought in an expert witness who said the star sprinter suffers from "generalised anxiety disorder," a condition that could have contributed to him shooting Reeva Steenkamp.
The outcome of his assessment may drastically alter the direction of the trial, with media reports suggesting that the three specialists who monitored him had come to a "unanimous" conclusion about his state of mind.