What will happen if my dog swallow benadryl itch gel

Your dog probably will: 1. get sick 2.barf it up 3. poop it out 4. or die. 1 of the 4.
(number 4 will be really sad):

Dogs can handle benedryl, however, you did not say how big of a dog you have or how much that size dog got. As a rule, I would PUSH water, for hydration, and be extra vigilant watching his/her behavior. Gel however; is not recommended for oral use, so really push the water...

Did you put it in the dogs mouth? Or did they lick it off their fur? Were you told by a vet to use it? Have you called your vet to see what to do? I would never use any medication made for humans on my dog unless my vet or someone I know that is knowledgeable advises it.

Dogs can handle benedryl.. formulated for the gut...

Topical ointments have a different make up.

If you are wanting to medicate with benedryl, why risk it.. go out and buy the pills...

I'd still advise to talk to your vet. Self medicating for what you may think is a problem can be very dangerous.