The 30-year-old – who is currently behind bars for the murder of his girlfriend Reeva Steenkamp – was initially thought to have suffered a heart attack, reports The Citizens.
Speaking with The Sun, a prison spokesman confirmed the news.
“We can state that offender Oscar Pistorius was taken to an outside hospital facility this morning for a medical examination, and is expected back in the facility later today,” the spokesman said.
It has since been confirmed that the Paralympian will be required to stay overnight for observation.
The double-amputee Olympic runner was initially convicted with manslaughter in 2014, but an appeal later saw his sentence upgraded to murder.
To date, he has served out a year of his six-year jail term.
This article originally appeared on New Idea.