Anyone else find the side effects of Hydrea 500MG frightening?

Posted by eddb @eddb, Oct 1, 2023

I was diagnosed with having a blood cancer that looks and acts a lot like Polycythemia Vera (PV) about 6 years ago. I’ve been rolling along ok with (mostly monthly) phlebotomies, until a year or so ago. At that point my white blood cells and (most importantly) my platelet levels started to increase. The doc did a 2nd bone marrow extraction but I STILL tested negative for PV. After a CT scan and other tests were done to rule out any possible hidden bodily infections, my doc prescribed Hydrea 500 MG. I filled the script about a week and a half ago…and it is still sitting in a bag on my counter, unopened. I got seriously freaked out when I researched the drug and found all those nasty side effects associated with the drug.

Now, I’m sitting here knowing that my platelet count as of 3 days ago was 987 (over twice the normal level limit) and that I could throw a blood clot at anytime. I was holding off taking the drug, to get an appointment with a hematologist/oncologist for a 2nd opinion, but that appointment isn’t for another 10 days - I’m a nervous wreck! I do not want to take the chance with hydrea but I don’t want to clot. I don’t even have a real diagnosis other than suspicion of bone marrow cancer or the beginning stages of it….

I’d be curious to hear about what others have experienced while on this drug. Much appreciated!

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I have been on Hydroxyurea for past 14 months. 500 MG daily. Had headaches and tired for first 8 months. Now, no side effects



I have been on Hydrea for over a year now for essential thrombocythemia. 500 mg daily and I've had no side effects


Diagnosed with PV and have been on Hydroxyurea for ~ 2 1/2 years… Currently taking 8500 Mg per week… That’s a lot of pills… Other than a slight thinning of hair, I have experienced no side effects and my monthly blood test results have been very good for over a year.. The idea of taking a chemo drug was and still is very concerning for me as well.. I know that this is an individual thing and know that many people can have very serious side effects that make taking Hydroxyurea intolerable… I stay very active, exercising every day, so maybe that is helping in my case ??
I hope that you find that HU doesn’t negatively impact you if it is necessary for you to take it..


I have been on Hydroxurea for 3 1/2 years and have had some skin changes, dryness of the skin and hair, some fatigue initially. I continue to stay active . Write down questions when you see the doc. The side effects to the drug override a stroke in my opinion. I hope you find that by taking the Hydroxurea you are not negatively impacted.


I have been on Hydroxyurea for 6 years and the side effects are headaches, itchiness and fatigue which, in my opinion, are better than risking a blood clot. Having ET has caused me to make many changes in my every day life and my entire life style but I do what I can in a day and deal with it. I had major, major fatigue without HU so I am grateful for a few good hours a day. Do not be afraid to try it and if it is not for you talk to your doctor about another route. Good luck with your journey


The only side affect I have had is tiredness, I avoid sitting in the sun you also have to remember 550mg per day is a very low dose. I have ET Jak2 and chronic myelofibrosis. I am 67 enjoying life embracing my diagnosis tying to lose some weight and living. Remember stress is a killer - people have been on Hydrea for may years Good luck and come here for support!


HU x 5+ years. No side effects to speak of. Less fatigue after I started it.

HU side effects are overstated, and there are a lot of fear-mongers out there. Ask doc to start you on lowest dose possible and work up. Drink 60 oz of water throughout the day, wear sunscreen, and don't handle pills without washing hands. I tip my caps from bottle into paper pill cup. Easy peasy.

I suspect some patients resist taking "chemo" because it means facing up to a cancer diagnosis. I felt that way a bit, and I took a week off work when I started HU because I expected horrors. None of my fears came true.

If you are freaking out about HU, ask about alternatives such as Pegasys or Jakafi. If you have PV, insurance might pay for those. It won't for ET.

Also: If you have kids at home, straighten your spine and be brave about taking care of yourself, including taking the meds the docs recommend. If they develop an MPN later in life, you will have modeled courage under pressure instead of denial and fear. Dad had ET, and his experiences and attitude really helped me.


I’ve been on Hydroxyurea every other day since last Nov. On my “pill days”, I feel a little more tired and get a headache if I don’t drink enough water. Very mild symptoms if any. The drug companies have to list all of the dire side effects due to legal liability. I’m more afraid of a clot.


If you are reading the package insert, I assume that means you trying to be an informed patient. However, the information in the package insert is part of the story, but it is not the whole story. Most package inserts list side effects, but they mostly do not list the probabilities of those side effects. Without the probability of occurrence, you really can't know what the risk is.

In project management, there is a discipline called risk management. We judge risk by multiplying probability of occurrence of the risk by the severity of its consequences. The most severe risks are the ones that are likely to occur and have severe consequences. A low risk would be one that is not likely to occur and the consequences are minimal. In the middle you can have combinations of high probability but low severity, or low probability but high severity. You don't have to make this judgment because your doctor already has done it.

The package insert can be useful if it raises an issue that maybe your doctor is not already aware of. For example, if there was a contraindication to taking the medication because of a condition that your doctor didn't know you had, that would be a reason to talk to your doctor about it.

I have a different type of blood cancer. I have had a lot of medications. At one time I was taking 38 separate pills per day. It was a challenge just to coordinate all of them to take them at the right time, with food, without food, etc. I have never really worried much about side effects of medications because I knew that they were needed so that I would not die.

However, I have had fear of other things that caused me to hesitate before jumping into a course of treatment. I understand fear. One of the things you can do is ask your doctor to explain the risks and benefits of taking the medication. I think that he or she would be interested in knowing if you have concerns about the medication.

I once asked my doctor what I could do to increase my chances of survival. He said to do two things: 1) keep all your appointments, and 2) take the medication.

Three years ago I was diagnosed with AML. Since that time I've had six different types of chemo drugs, antibiotics, antivirals, antifungals, a bone marrow transplant, immunosuppressants, and others. I am still alive today.

If you have a concern before starting the medication, talk your doctor. If you start taking the medication and have a further concern, talk to your doctor about that. That seems like a rational course of action that I think would serve you well.


After asymptomatic high platelets in the 600 range, a bone marrow biopsy revealed JAK2 and I took Hydrea 500mg daily. I immediately experienced throbbing headaches, including four migraines, and developed debilitating fatigue and lethargy. After three months, my platelets had dropped into the 400 range but I needed more energy to train for an upcoming wilderness backpacking trip. Because I am at low risk other than age--71--for clots, my hematologist OK'd stopping hydrea unless platelets approached 1000.

I felt better soon after discontinuing Hydrea, with more energy, less brain fog, and fewer headaches, and had a fabulous week in the wilderness. At recheck last week, after two months off Hydrea, platelets were 628 and all other CBC and blood chemistry values were normal. The hematologist suggested trying 500mg Hydrea 3 days weekly which I'm considering with much concern based on the side effects I already experienced and others listed for this drug. I'm also considering getting a second opinion and asking about other treatment options.

Each of us must come weigh our own conditions, risks, and considerations about quality of life when deciding which treatment is right for us. Best of luck in finding the best care and treatment for your blood disorder!

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