I have polycythemia and that causes itching. And I do mean ITCHING. Prior to starting treatment, I absolutely mauled my ankles to death. Anyhow, I tried antihistamines, calamine lotion, you name it. Nothing worked. What works for me:
1. Cool showers and baths. Specifically, I lather up and only turn the water on long enough to rinse off.
2. Aveeno Skin Relief Body Wash. It is formulated for dry itchy skin. My skin isn't dry, but this stuff really helped.
3. I massage Aveeno lotion or cream into the itchy areas after every shower or when I itch.
4. And I DO NOT SCRATCH.

Don't scratch, ever. Scratching causes a histamine reaction and that makes the itching much much worse.