[header] How to stop a cat from pulling its hair out [title] Understand pet allergies. [step] If humans have an allergy, say for instance hay fever, we tend to get sore eyes, a runny nose, and sneeze. Cats, however, react differently. 
The commonest manifestation of an allergy in cats is itchy skin, which in turns results in excessive grooming and pulling hair out. [substeps] In much the same way that some people have a peanut allergy, or a seafood allergy, or get hay fever, a cat may be allergic to one substance and be fine with another.