If the antihistamines are not working, try alternative therapies. Itching has a similar path that pain has and is considered by many to be a light version of pain. My itching has greatly decreased since my doctor switched me from HU to Jakafi. I also started taking Quercetin and Bromalain. There is a lot of evidence supporting the use of Jakafi and Quercetin. I take Bromalain because it is known to reduce pain. My research also shows good results from Gabapentin and phototherapy (311 NM, in the ultraviolet range). Talk to your doctor about these things.

Thank you for the information I have to do something because I am going crazy with the itching. The dermatologist wasn't very helpful, he reckons he could give me medication but then I wouldn't have a life because I wouldn't be able to drive while taking it.

If you are into any heavy reading about the itching especially with Polycythemia Vera, I suggest looking up articles at https://pubmed.ncbi.nlm.nih.gov. You can find a lot of helpful information on that site related to our common diseases. I am referring especially to an article entitled: Skin mast cells in polycythaemia vera: relationship to the pathogenesis and…
It explains so much about the mast cell activation syndrome and why that is more technical than I can explain about how in the overproduction of the red blood cells, some of the dead cells are getting pushed to the skin, which in turn leads to the itching. I’m just a retired nurse who likes to read everything I can find online about these MPN’s, so bear with me about probably my poor interpretation.

My legs get super itchy most nights. I use Eucerine Calming Cream, it works pretty good for me.
If I get overheated or suddenly cold I break out in hives. Ugly and itchy!

Before I knew that I had PMF, I would sting, burn, itch all over after a shower. Then I started Jakafi and I do not sting unless it is really cold out. I quit taking shower everyday as I could not stand the stinging. Crazy, right.