The only thing here that is capable of causing allergies is an allergen. Hence the name, it stimulates an immune response to a harmless antigen.
An antihistamine is a substance the prevents the swelling of certain areas of the body due to an increase in histamine production in that area.
An antibody is a type of white blood cell that fights disease.
Bacteria are microscopic organisms that are capable of doing a variety of different things, none of which are pertinent to your question.
I hope I helped!
If you'd like me to elaborate on my response, then just leave a comment down below and I'll gladly do so. :)
(I'll also help you with other topics/questions, if needed).
