Fifty learners were treated for food poisoning after eating muffins at a high school in Mokopane, Limpopo, paramedics said on Saturday.
Netcare911 spokesperson Nick Dollman said the learners had stomach cramps and were vomiting.
Dollman said 20 of the learners were rushed to hospital.
"It was suspected that they may have had food poisoning and additional resources were requested to assist at the scene."
The incident is being investigated.