
Oprah Winfrey was MIA from CBS this week, despite previously being announced as a guest to plug a new book -- and the reason is simple ... she was pooping and barfing.
O's bestie Gayle King got a little TMI during "CBS Mornings" Tuesday -- where she and the other anchors were hosting author David Wroblewski ... who's got a new book out that Oprah trotted out as the latest addition to her famed book club.

Gayle explained Oprah's absence -- saying she'd caught a bad stomach bug that landed her in the hospital. Then, a bit more detail about how it was affecting her ... and it's gnarly.
She explained ... "She had some kind of stomach thing -- stomach flu -- stuff was coming out of both ends. I won't get too graphic. Needless to say, she ended up in the hospital, dehydration, had to get an IV, it was a very serious thing."
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