My whole body is itching for so long and I had taken the drug hydroxyzine hydrochloride tablets USP atarax 25mg?

Many Causes of Itch. Your itching can be caused by many things only some of which would be helped by Hydroxyzine. Dry skin Is a very common cause. Itching can also be caused by liver or thyroid problems. Allergies and eczema are another cause. You really need to see a physician to help you sort this out.
Cause of itch? You need to find out what the cause of the problem is. That medication you listed does help with itching, but I would recommend seeing your doctor or a dermatologist to help assess the problem.