The Health and Human Services Department refused to provide a specific diagnosis for Azar, saying only that he was treated with intravenous antibiotics for a "minor infection."
Azar, 50, wrote on Twitter Monday that he had been released.
He thanked his wife for insisting that he call his doctor when he wasn't feeling well and said he's glad to be back at work.
HHS announced Sunday night that Azar had been admitted to the hospital "out of an abundance of caution."
Azar often goes home to Indiana on the weekends.
He's President Donald Trump's second health secretary, and he's currently working on an administration plan to try to reduce prescription drug costs.
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