Secretary of State Hillary Clinton, who cancelled a planned overseas trip last weekend because of illness, is recovering at home after fainting due to dehydration and sustaining a concussion, a US State Department spokesman said.
"While suffering from a stomach virus, Secretary Clinton became dehydrated and fainted, sustaining a concussion," Clinton spokesman Philippe Reines said in a statement.
"She has been recovering at home and will continue to be monitored regularly by her doctors. At their recommendation, she will continue to work from home next week, staying in regular contact with department and other officials. She is looking forward to being back in the office soon," Reines added.
Clinton fell ill with a stomach virus last weekend and was forced to cancel a planned trip to the Middle East and North Africa. The virus also hit other members of her staff, who were accompanying her on a recent European trip.
Clinton has maintained a punishing schedule in the final weeks of her tenure as the top US diplomat, a position she says she intends to leave toward the end of January when US President Barack Obama is sworn in for a second term.
Clinton has been expected to testify on Dec. 20 before the House of Representatives and Senate foreign affairs committees on a report on the deadly attack on the U.S. diplomatic post in Benghazi, Libya, that killed the US ambassador and three other Americans and raised questions about adequate security at far-flung posts..
Republicans have criticized the Democratic Obama administration for its early public explanations of the attack.
Much of the criticism focused on US Ambassador to the United Nations Susan Rice, who on Thursday said she was withdrawing her name from consideration to replace Clinton as secretary of state to avoid a potentially disruptive confirmation process.
Clinton came tantalisingly close to winning the Democratic presidential nomination four years ago and has consistently been rated as the most popular member of Obama's cabinet, leading to speculation she might mount another White House bid in 2016.
But she has repeatedly played down suggestions she might still harbor presidential aspirations, saying she might work in philanthropy or academia.