I'm an active 84 yr old female diagnosed with ET 2 years ago. My platelets rose to about 800,000 and I was hospitalized with multiple pulmonary embolisms. My Hemotologist started me on 500 mg HU daily. My platelets dropped to 240,000 quickly. I experience NO side effects. I truly believe if you are looking for side effects you will have them. The power of suggestion can be strong. Believe me you do not want pulmonary embolisms!! Take your medication and move on with your life.