As long as you are not experiencing serious side effects and the HU is lowering/controlling your platelet count, you can take it indefinitely. I'm sure others will chime in soon and you'll see that we all have different experiences with this drug. I was diagnosed in October, 2023 at age 67. Platelet count was 792 and I started on 500 mg of HU 2 times a day, 7 days a week. As my platelet count dropped my dose was reduced and I have been on 500 mg 2x a day, 4 days a week for about the last year. My platelets hover around 200 and my heme/onc is happy (as am I). My only side effect was I initially had sharp, sudden and very brief headaches, which subsided as my body adapted and as my dosage was reduced. I also experienced some hair loss but that has also subsided. Good luck to you on this journey!