"Police swiftly responded to a call [on Saturday] when 18 victims passed out as a result of eating food they bought from a restaurant at the Rustenburg taxi rank," said Constable Provia Tseke in a statement.
"All eighteen victims were taken to the Job Shimanke Tabane Hospital in Rustenburg in a serious but stable condition."
The 18 were discharged from hospital at 15:00, three hours after eating the food.
Rustenburg police have opened a case against a 38-year-old woman following the incident.
"A sample of the food has been taken to be tested," said Tseke.