@cetzler I have had no side effects except constipation and very mild hair thinning. The hair thinning reversed after a few years. This is not "I have bald spots!" thinning in my case. I was having severe fatigue before starting HU. I felt better after I started it.

Other people have nausea, insomnia, or diarrhea. My doc prescribed Compazine (anti nausea) for me with HU, but I never needed it.

Starting HU as soon as it is warranted and at lowest possible dose, increasing only to whatever keeps you in stable is what most docs do, and this gives patients time to acclimate. If you wait to start HU and let platelets run high, a doc may start you on a higher HU dose, which you may not tolerate well.

Any platelets over 450 can be "dangerous" depending on mutation type, age, and clot history. Yr doc should be able to give you Vegas odds on developing a clot if you don't take HU vs if you do. There is statistical research that shows people on HU have fewer clots and live a normal lifespan.

My dad also had ET. No one knew it until he had a leg clot. He had to go on coumadin, which threw him in the hospital a couple times for internal bleeding.

I get why your daughter is nervous about HU. It has a scary "black box" warning. The big question is whether YOU feel nervous about it and whether you think your daughter has more experience and knowledge than the doc who wants to prescribe it.

There are alternatives to HU--anagrelide and Besremi. Besremi is usually rejected by insurance for ET patients because it is super expensive. But if you are rich or have great insurance, you could ask yr doc about that.

Fwiw, I have family that gave me a hard time about my treatment. But it's not their body, and I am glad I chose the options I did.

@cetzler

nohrt4me makes a great point.

Ask your daughter how many patients she knows with ET.

Then ask your oncologist the same question.

Please remember, you're among friends here.

You must find your own way forward, but you are not alone.