Secretary of State Rex Tillerson canceled his public schedule in Kenya on Saturday due to illness.
He is feeling unwell after long days working on major issues such as North Korea, said Steve Goldstein, the undersecretary of state.
Tillerson arrived Nairobi on Friday, where he met with president Uhuru Kenyatta.
Tillerson arrived in the county on Friday evening and was scheduled to lay a wreath at the site of the 1998 bombing of the U.S. embassy in Nairobi, in which more than 200 people were killed.
The PEPFAR event went on without him, while the embassy visit was scrapped. While the nature of the illness was not disclosed, it was understood not to be serious, the BBC reported.
A rigorous schedule that included stops in three African countries Friday has been made even more strenuous for Tillerson by events in Washington.
Tillerson had started his day Friday in Ethiopia with the North Korea announcement and flew to Djibouti for a brief visit before continuing on to Nairobi.
Mr Tillerson was in the Ethiopian capital of Addis Ababa when news of Donald Trump's agreement to meet Mr Kim in unprecedented talks broke late on Thursday.
Tillerson was received to the country by American ambassador to Kenya Robert Godec, Foreign Affairs Cabinet Secretary Monica Juma and Chief Administrative Secretary Ababu Namwamba among other government officials.
He plans to spend another day in Nairobi before heading to Chad and Nigeria on Monday and Tuesday.