Itching (puritis) is the symptom that led me to oncology. It was zyrtec that relieved the itching for me. After about 5 years, I cut back then was able to quit it.
Then when I was diagnosed with pv in addition to mgus/smouldering myeloma, was when I started Hydroxyurea. Occasionally I have itching now when, for some reason, the histamines act up, then I will take a zyrtec.