Call a vet clinic. Don't give him peroxide because this could do more harm. If they are DIAMOND matches then I don't think they are poisonous. I doubt any brands are poisonous because of what this article says.
http://inventors.about.com/library/i...rs/blmatch.htm
sulpher is used as a food additive too....but large amounts are dangerous. So, I guess it would be best to call a vet to be on the safe side.
Don't worry!