Cold turkey moment for ginormously germaphobic HOWIE MANDEL – who claims he’s been warned by a medical expert to STOP…

what?...USING…

oh, no!...

HAND SANITIZER…

shriieeek!

The obsessive/compulsive “America’s Got Talent” judge told pals he was told that because he’s been using sanitizer so often, it killed off too much good bacteria – and that’s why he’s developed nasty warts on his hands.

(Say WART?! I never knew that, did you? Tweet me @IMwalkergossip)