The company's shares were down 2% in extended trading.
Hurd is one of Oracle's two CEOs, the other being Safra Catz. Under their tenure, the company has tried to rapidly transition to cloud computing software.
Catz and Oracle founder and Chief Technology Officer Larry Ellison will cover Hurd's responsibilities during his absence, the company statement said.
Hurd will continue to receive all employment benefits during his leave, Oracle said. The company did not respond to Reuters request for details on Hurd's health issue and how long his leave would last.
Hurd was named Oracle co-president in September 2010, a month after he was ousted in a controversial fashi
on from Hewlett-Packard Co, where he had been chief executive since 2005. (https://reut.rs/2kfZh1Z)
When Hurd and Catz were named co-CEOs in 2014, analysts were skeptical about the move. However, cloud software giants like Salesforce.com Inc have since also had a co-CEO structure in place.
"Mark Hurd is a talented executive, but I don't think Oracle will act differently," Wedbush Securities analyst Steve Koenig said.
Separately, Oracle reported quarterly results a day before its scheduled release. On a post-earnings call with analysts, Catz said, "...as Mark will be taking a leave, we felt it made sense to share all of our news at once."
Total revenue came in at $9.22 billion, missing estimates of $9.29 billion, according to IBES data from Refinitiv.
The miss indicated Oracle was struggling to make inroads into the highly competitive cloud computing market dominated by the likes of Microsoft Corp and Amazon.com Inc.
Oracle has been aggressively pushing into cloud computing to make up for a late entry into the fast-growing business that helps companies move away from the traditional and costlier on-premise model.
The company also said, assuming currency headwind, it expected second-quarter adjusted profit between 87 cents and 89 cents per share, below estimates of 91 cents per share.
Net income fell to $2.14 billion in the quarter ended Aug. 31, from $2.27 billion a year earlier. On a per share basis, Oracle earned 63 cents per share from 57 cents per share, a year ago.
Excluding items, Oracle earned 81 cents per share, in-line with analysts' expectations.
Oracle also said it plans to buy back an additional $15 billion in stock.
(Reporting by Arjun Panchadar in Bengaluru; Editing by Shailesh Kuber)
By Arjun Panchadar