Zambian President Edgar Lungu collapsed Sunday in the capital, Lusaka, while presiding over a women's day celebration.
Lungu was rushed to a local military hospital, where authorities say he is undergoing treatment for malaria and exhaustion.
In a statement, the 58-year-old president later said doctors diagnosed "high levels of fatigue." The statement also said he was advised to rest and "that there is nothing to worry about."
Lungu assumed the presidency in January after the death of former President Michael Sata, who died in London in late October after a long illness.
The French news agency said President Lungu, who collapsed after standing for about 20 minutes at a podium, also is rumored to suffer from diabetes.