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Treatment Name: Hydroxyurea (Hydrea®, Droxia®)

Hydroxyurea (Hydrea®, Droxia®) is a Treatment Regimen for Polycythemia Vera

How does hydroxyurea work?

  • Hydroxyurea inhibits the formation of DNA by blocking an enzyme known as ribonucleotide reductase. This results in the decreased ability of the bone marrow to produce red blood cells. By slowing down the production of red blood cells in the bone marrow, hydroxyurea decreases the number of red blood cells in blood vessels
  • Hydroxyurea reduces the white blood cell count and platelet count as well

Goals of therapy:

  • Hydroxyurea is primarily given to prevent life-threatening complications of polycythemia vera such as blood clots. Watch our video on blood clots below to learn more.
  • Hydroxyurea is also given to decrease symptoms from polycythemia vera such as erythromelalgia, and aquagenic pruritus

Unless otherwise specified by your doctor, goal blood levels are as follows:

  • Goal Hematocrit: Less than 45%
  • Goal White Blood Cell count: Less than 10,000 cells/mcL
  • Goal Platelet count: Less than 400,000/mcL

Hydroxyurea is not given with the goal of cure.


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How is hydroxyurea therapy for polycythemia vera taken?

  • Usual hydroxyurea starting dose: Hydroxyurea 500 mg by mouth once daily or 1000 mg by mouth once daily
  • Hydroxyurea is usually taken at home until the treatment stops working or until unacceptable side effects occur. The dose is adjusted based upon blood counts. Taking hydroxyurea with food may help with upset stomach or nausea.
  • Depending upon your risk factors for developing a blood clot, your doctor may recommend that you take a baby aspirin (aspirin 81 mg) once daily to reduce the risk of having a stroke, heart attack, blood clot in the lung, liver, or in other areas.

Click here for the common hydroxyurea starting doses.

Note: Individual doses may vary based upon your Doctor's recommendation, or drug availability.

Side Effects

What are the most common side effects from hydroxyurea for polycythemia vera?

In clinical studies, the most commonly reported side effects of hydroxyurea (Hydrea®, Droxia®) are shown here:

  • Mouth ulcer (10%)
  • Skin ulcer on leg (9%)
  • Stomach pain and diarrhea (7%)
  • Dry skin (7%)
  • Low platelets, increased bleeding risk (4%)
  • Inflammation of the bladder (2%)

Note: Hydroxyurea may also lower good white blood cells known as neutrophils leading to neutropenia. This may temporarily increase the risk of infection. Hydroxyurea may also lower red blood cells leading to anemia

Watch videos on common hydroxyurea therapy side effets below

Side effect videos Side Effect Videos
Nausea and VomitingNausea and VomitingDiarrheaDiarrheaBleedingBleedingAnemiaAnemiaBlood ClotsBlood Clots


How often is monitoring needed?

Labs (blood tests) may be checked before treatment and periodically during treatment until stable. Labs may be checked as often as once weekly during the first 6 months unless a stable dose has been achieved and the hemoglobin/hematocrit, white blood cell count, and platelet counts are within the desired goal range. Thereafter, depending upon your dose and situation, your doctor may require labs as little as once every 3 months. Labs often include: Complete Blood Count (CBC), Comprehensive Metabolic Panel (CMP), folic acid, and vitamin B12, plus any others your doctor may order.

How often is imaging needed?

Imaging may be checked if there is concern for a blood clot, significant bleeding, or an infection. Imaging may include: X-rays, magnetic resonance imaging (MRI), or computerized tomography (CT) scans.

How might blood test results/imaging affect treatment?

Depending upon the results, your doctor may advise to continue hydroxyurea as planned, reduce the dose, temporarily stop treatment until the side effect goes away, or switch to an alternative therapy.

If your hematocrit is higher than 45%, your doctor may recommend that you increase your dose of hydroxyurea until the hematocrit is less than 45%. An increase in hydroxyurea dose may not be possible if your white blood cell count or platelet count are too low. In this case, a change in therapy may be required.

Some doctors may recommend a decreased starting dose of hydroxyurea by up to one-half if your kidney function is decreased (as determined by the serum creatinine on the CMP test as described above). The dose will then be adjusted based upon response and whether you are experiencing any side effects.

Note: Doctors can often tell if you are taking hydroxyurea as prescribed by looking at the results of your blood tests, specifically the CBC (see complete blood count above)

  • If hydroxyurea is taken every day, the MCV, or mean corpuscular volume, often rises after taking hydroxyurea for several months. 
  • If your MCV is not elevated, this can be a clue that you are not taking hydroxyurea everyday

ChemoExperts Tips

What are the most important things to know about hydroxyurea when receiving treatment?

  • Because hydroxyurea lowers the white blood cell count (a high white blood cell count is a risk factor for blood clots in patients with polycythemia vera), it may be a preferred treatment over phlebotomy in patients with polycythemia vera and an elevated white blood cell count
  • If hydroxyurea causes nausea, it may be taken with food, preferably in the middle or at the end of a meal
    In addition to controlling blood counts (as defined in goals of therapy above), other risk factors for blood clots such as diabetes, high blood pressure, and high cholesterol should be managed as well
  • Patients with polycythemia vera often develop pain and redness in the hands and feet. This condition is known as erythromelalgia. If you have erythromelalgia, your doctor may recommend a baby aspirin (aspirin 81 mg) to decrease the redness and pain in your hands in feet. On occasion, larger doses of aspirin are needed. Check with your doctor or pharmacist before you take aspirin to make sure it is safe
  • Hydroxyurea may cause skin ulcers with the legs or mouth being the most common sites of the body where these occur. Contact your doctor if you develop painful sores or notice significant changes to any area of your skin
  • Patients taking hydroxyurea long-term (for multiple years) have reported the development of skin or other cancers. Although the exact risk is unknown, it is thought to be less than 4% of patients. It is recommended that patients taking hydroxyurea see a dermatologist for any suspicious looking changes in their skin
  • Although hydroxyurea has been associated with leukemias, data suggests that hydroxyurea does NOT cause leukemia, even when used for many years. In the rare case where a patient develops leukemia while taking hydroxyurea it is possible that the leukemia would have developed if hydroxyurea was not used at all
  • Hydroxyurea may mask a folic acid or vitamin B12 deficiency. Some doctors may recommend checking for a folic acid (vitamin B9) or vitamin B12 deficiency before beginning therapy or periodically while taking hydroxyurea if you have signs or symptoms of too little of these vitamins.
  • A pharmacist should ALWAYS review your medication list to ensure that drug interactions are prevented or managed appropriately
  • Clinical trials may exist for polycythemia vera. Ask your doctor if any studies are currently enrolling in your area. If not, go to to search for other centers offering study medications

Patient Assistance & Co-payment Coverage

Patients under the age of 65 years, or those with private insurance plans:
If you have insurance and are looking for patient assistance or copay assistance for Hydroxyurea (Hydrea®, Droxia®), we have provided links that may help.

Visit our Patient Assistance page and click the links to various patient assistance programs for help paying for Hydroxyurea (Hydrea®, Droxia®). Depending upon your income, they may be able to help cover the cost of:

  • Hydroxyurea (Hydrea®, Droxia®)

For Branded medications (may be available for generic medications too), check with the manufacturer to determine if a co-pay card is offered and if it could reduce your monthly copay.

  • If you are uninsured, check with the manufacturer to determine if you are eligible to receive medication at no cost.

Medicare and Medicaid patients (Patients 65 years or older):
The clinic providing treatment will likely pre-authorize medications and immune therapies such as Hydroxyurea (Hydrea®, Droxia®) and are the best source to help you understand drug cost.

  • Ask to speak with a patient assistance technician or financial counselor at the clinic or hospital administering this therapy.

Emotional Wellness

What is Emotional Wellness?
Emotional wellness is having a positive outlook balanced with a realistic understanding of current life events. This requires both an awareness and acceptance of your emotions. It is with this knowledge that you can develop a plan to take the necessary actions to positively impact your life.

Emotional wellness uses an ongoing process to continually reflect on the stressors of life in a constructive manner to move forward and create happiness.

Because emotional wellness is deeply connected with physical, social, and spiritual wellness, pursuing it often becomes particularly difficult in times of major illness. Despite this difficulty, working toward emotional wellness has been connected to improved treatment outcomes and a higher likelihood of achieving goals of therapy.

Learn more about pursuing emotional wellness while receiving treatment with Hydroxyurea (Hydrea®, Droxia®)

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1) Najean Y and Rain JD. Treatment of polycythemia vera: the use of hydroxyurea and pipobroman in 292 patients under the age of 65 years. Blood. 1997;90:3370-3377.

2) Marchioli R, Finazzi G, Specchia G, et al. Cardiovascular events and intensity of treatment in polycythemia vera. N Engl J Med. 2013;368:22-33.

3) Barbui T, Vannucchi AM, Finazzi G, et al. A reappraisal of the benefit-risk profile of hydroxyurea in polycythemia vera: A propensity-matched study. Am J Hematol. 2017;92:1131-1136.

Created: August 7, 2018 Updated: August 7, 2018

What is Polycythemia Vera?

Polycythemia refers to an increased production of red blood cells. There can be many causes of this, including smoking, sleep apnea, or living at high altitudes.

Polycythemia Vera, or "P. Vera", also causes increased red blood cell production, and is almost always the result of a gene mutation known as "JAK2V617F."

P. Vera may increase the risk of a blood clot, such as a heart attack or stroke. Very rarely, it may transform into another disease such as myelofibrosis or acute myeloid leukemia, however this often takes several decades.

Peginterferon alfa-2a (Pegasys®) and ruxolitinib (Jakafi®) are common treatments for polycythemia vera. Please click on the treatment options below to learn more.

NOTE: Treatment Options listed below are not all-inclusive. Other treatments may be available. ChemoExperts provides drug information and does not recommend any one treatment over another. Only your Doctor can choose which therapy is appropriate for you.

Common Hydroxyurea starting dose

Usual hydroxyurea starting dose:

1. Usual starting dose: Hydroxyurea 10 - 15 mg/kg/day. This dose is taken by mouth either once daily or twice daily.
2. Doses of 1,500 mg or greater are sometimes better tolerated if they are divided into two or more doses. For example, 1,500 mg per day could be taken as 500 mg each morning and 1,000 mg each night.
3. If you have upset stomach after taking hydroxyurea, try taking it with a little food
4. On occasion, hydroxyurea doses higher than 1,500 mg per day may be prescribed to achieve normal blood counts, but are often not necessary long-term to maintain normal blood counts in polycythemia vera

Clinical Studies

1) Najean Y and Rain JD. Treatment of polycythemia vera: the use of hydroxyurea and pipobroman in 292 patients under the age of 65 years. Blood. 1997;90:3370-3377.

2) Marchioli R, Finazzi G, Specchia G, et al. Cardiovascular events and intensity of treatment in polycythemia vera. N Engl J Med. 2013;368:22-33.

3) Barbui T, Vannucchi AM, Finazzi G, et al. A reappraisal of the benefit-risk profile of hydroxyurea in polycythemia vera: A propensity-matched study. Am J Hematol. 2017;92:1131-1136.

What is a CBC?

A Complete Blood Count (CBC) is a frequently ordered blood test that tells clinicians the status of your: 1) White blood cell count, 2) Hemoglobin, and 3) Platelet count at the time the test was taken.

Common uses:
1) White blood cell count (WBC): is used to determine infection risk, or response to chemotherapy. Certain chemotherapy agents may harm our good infection-fighting cells. Sometimes chemotherapy may need to be delayed to allow these cells to recover.

2) Hemoglobin: is used to determine if someone is anemic. Anytime the hemoglobin is below 12 g/dL, the person is said to be anemic. Red blood cell transfusions, and sometimes iron can be given to restore the hemoglobin level, but anemia treatment should always aim at treating the underlying cause or condition.

3) Platelet count: is used to determine if the risk of bleeding is increased or if a platelet transfusion is required to prevent bleeding. Certain medications that increase bleeding risk, such as: aspirin, certain chemotherapy agents, and blood thinners, may need to be stopped temporarily until the platelet count is within a safe range.

What is a CMP?

A Comprehensive Metabolic Panel (CMP) is a frequently ordered blood test that tells clinicians the status of your: 1) Electrolytes & Acid/Base status2) Kidney function, 3) Liver function, 4) Blood sugar, and 5) Calcium at the time the test was taken. It is commonly used to monitor liver and kidney function when beginning new medications such as chemotherapy. A total of 14 tests are run simultaneously and are shown below.

Electrolytes & Acid/Base status:
1) Sodium, 2) Potassium, 3) Carbon dioxide, 4) Chloride

Kidney Function:
5) BUN (blood urea nitrogen), 6) Serum creatinine (Scr)

Liver Function:
7) AST, 8) ALT, 9) Total bilirubin, 10) Alk Phos, 11) Albumin, 12) Total protein

Blood sugar:
13) Serum glucose

14) Serum calcium