my doc said that if i can't take biaxin that she won't write a prescription for zithromax unless it is taken off my chart that I get rash and itch from it. I have found that anything that has hydrochloride in it makes me get a rash or hives and itch. she says in the same family of drugs. I'm allegric to citric acid, oranges, etc. , things that have acid in them.