My son is 3 1/2 and has been on hydroxurea for maybe a year or so. I do feel like his most recent crisis was less severe as it was manageable from home for the first time. We had many concerns as well. For young children they give a very low dose and work their way up while monitoring how they do and their hemoglobin and whatnot(mom is the medical expert). I recommend giving it a try as we switched doctors due to relocating recently and no matter where we are hydroxurea seems to be the gold standard at the moment.