Someone being allergic to, or potentially allergic to, a service animal is not a legally valid reason for a handler to be denied access with their service animal. According to the ADA, if there is someone with a disabling allergy, both disabilities must be accommodated without denying access to the handler with the service animal.

However, I do use Allerpet D on my service dog. He is a Rott-Aussie mix with an Aussie coat. I'm a teacher and he's in the classroom with me. We've never had a problem with other's allergies.