I was diagnosed with Polycythemia Vera (PV) a year ago. The pruritus was a symptom before diagnosis. Hydroxyurea helped manage blood, but not symptoms, so now I am taking Jakafi in addition to Hydroxyurea and have very minimal itching now so I can shower and swim again!
What helped somewhat before showers was to apply thin coating of coconut oil over body, then after drying (without rubbing) off I still apply Trader Joe’s coconut body butter. It’s not greasy and doesn’t have overpowering coconut smell. And it’s not expensive.
Hope you get relief!