I use tegretol for decades. yesterday there was a sticker on it for the first time, that warned against the use of grapefruit and tegretol. why?

Tegretol: Grapefruit juice might increase how much carbamazepine (Tegretol) the body absorbs. Drinking grapefruit juice while taking carbamazepine might increase the effects and side effects of carbamazepine.

Grapefruit and grapefruit juice can increase how much Tegretol gets into a person’s body. This increases the chances of a person having unwanted side effects from Tegretol, such as feeling dizzy, drowsy, or off-balance.