I’m no Dr. but I believe the HU is prescribed first.. I was almost 67 when I was diagnosed in spring of 2021… I had 4 phlebotomies(1 per week for a month), was put on aspirin, and HU… My oncologist’s main focus was lowering the HCT which was very high… I should say that I never even heard of PV before I was diagnosed… In my case, I have tolerated the HU very well.. I currently am taking 7500 mg per week.. I am also very active.. I bike every day as long as the weather allows for it and also do a lot of walking… Long sleeves and sunscreen are a must on sunny days… Honestly, despite taking HU, I feel really good.. no symptoms, high energy, no issues.. I also understand that some people cannot tolerate HU at all… It effects people differently… Hope this helps and best of luck to you and your husband..