While in the pet shop the other day I came across a bottle of stop itch.

Aristopet Stop-Itch Lotion 250ml

My brothers dog Buddy had fleas as a puppy and chewed all his skin raw at the base of his tail/up his back. It seemed like a good product to use on him, so I brought it.
I put it on him today (not a lot, just dabbed it with a cotton wool ball.) and my brother just brought him over as he has been vomiting.

My brother is blaming me for making his dog sick. My brother has left him here and he hasn't been sick since. He curled up on clothes in the bathroom and is sleeping.

Can the stop itch make dogs sick (Im guessing he has been licking/biting at it) or could it be something else?