US Secretary of State Hillary Clinton, 65, suffered a concussion earlier this month when she fainted from dehydration after a stomach virus. Incapacitated for three weeks, she is now being treated with anti-coagulents. Clinton is due to stand down when President Barack Obama begins his second term next month. Sen. John Kerry has been nominated to succeed her. She is the most traveled secretary of state in history having visited 112 countries, according to AP. In January, Clinton is due to testify before a Congressional committee on the attack in September on the US consulate in the Libyan city of Benghazi, in which the US ambassador to Libya and three American officials were killed. Depending on her state of health, she may not make it before the end of her term.