Brandy Says Dehydration Made Her Leave Stage Abruptly

Brandy says a medical incident drove her offstage in Chicago Saturday night … revealing a sudden wave of dehydration threatened to make her faint.

The singer-songwriter explained her sudden departure from her United Center show in an Instagram post Sunday morning … telling her fans that — after weeks of nonstop rehearsals — she experienced feelings of dehydration during the show.

Brandy says she did return to the stage after initially leaving it … but adds she couldn’t connect to the tunes sonically — and acknowledges it wasn’t her best show by any stretch of imagination.

After leaving the show, Brandy says she went to a local doctor … and she’s taking proper precautions to avoid a situation like this in the future.

Brandy adds she’s deeply grateful to Monica for stepping up in a tough situation … as well as the entire crew for their support.

We shared video with you of Brandy bailing from the stage last night … and, at first glance, it seemed she was frustrated with sounds issues — which makes total sense now given she herself said she couldn’t quite connect with the music the right way.