Winnie Madikizela-Mandela was admitted to the Milpark hospital on Wednesday, a spokesperson confirmed.
Madikizela-Mandela has been admitted for observation, her spokesperson, Victor Dlamini, said on Thursday.
He was unable to provide any additional information.
Madikizela-Mandela stayed briefly at the Milpark Hospital in December for observation.
In April, she was in a hospital after undergoing back surgery. — News24