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Hydroxyurea Tablets

Hydroxyurea is a chemotherapy medication that manages sickle cell anemia crises. Crises cause sudden, intense pain that affects several parts of your body. This medication comes in a tablet form that you can take by mouth with a glass of water as directed.

What is this medication?

HYDROXYUREA (hye drox ee yoor EE a) prevents the symptoms of sickle cell disease, such as pain crises and acute chest syndrome. It may also reduce the need for blood transfusions. It works by keeping red blood cells round and flexible, which prevents blood cells from clumping together. This also increases blood flow and the amount of oxygen that gets to your tissues.

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This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Mylocel, Siklos

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

  • Gout or high levels of uric acid in your blood
  • HIV or AIDS
  • Kidney disease or on hemodialysis
  • Leg wounds or ulcers
  • Liver disease
  • Prior or current interferon therapy
  • Recent or ongoing radiation
  • Recent or upcoming vaccine
  • Use a continuous glucose monitor (CGM)
  • An unusual or allergic reaction to hydroxyurea, other medications, foods, dyes, or preservatives
  • Pregnant or trying to get pregnant
  • Breastfeeding

How should I use this medication?

Take this medication by mouth with a full glass of water. Take it as directed on the prescription label at the same time every day. If you are not able to swallow the tablet, you can dissolve it in a small amount of water in a teaspoon and swallow it right away. Your care team may change your dose or tell you to stop taking this medication if you get side effects. Do not change your dose or stop taking it unless your care team tells you to.

Handling this medication may be harmful. Wash your hands before and after touching the medication or the bottle. Wear gloves while touching the medication or bottle. Talk to your care team about how to handle this medication. Special instructions may apply.

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This medication comes with INSTRUCTIONS FOR USE. Ask your pharmacist for directions on how to use this medication. Read the information carefully. Talk to your pharmacist or care team if you have questions.

A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.

Talk to your care team about the use of this medication in children. While it may be prescribed for children as young as 2 years for selected conditions, precautions do apply.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medication?

  • Antivirals for HIV, such as didanosine or stavudine
  • Live virus vaccines

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

Visit your care team for regular checks on your progress. Report any side effects. Continue your course of treatment even if you have side effects unless your care team tells you to stop.

You may need blood work done while you are taking this medication.

This medication may increase your risk of getting an infection. Call your care team for advice if you get a fever, chills, sore throat, or other symptoms of a cold or flu. Do not treat yourself. Try to avoid being around people who are sick.

Talk to your care team about your vaccination history. Some vaccines are not recommended in people taking this medication. Your care team can help you decide which vaccines are safe for you.

Talk to your care team about your risk of cancer. You may be more at risk for certain types of cancer if you take this medication. To lower your risk of skin cancer, keep out of the sun. If you cannot avoid being in the sun, wear protective clothing and sunscreen. Do not use sun lamps, tanning beds, or tanning booths.

If you wear a continuous glucose monitor (CGM), this medication may affect your sensor blood sugar (glucose) results. Talk to your care team about whether it is safe to use your CGM to dose insulin.

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Talk to your care team if you or your partner may be pregnant. Serious birth defects can occur if you take this medication during pregnancy and for 6 months after the last dose. You will need a negative pregnancy test before starting this medication. Contraception is recommended while taking this medication and for 6 months after the last dose. Your care team can help you find the option that works for you.

Do not handle this medication if you may be or could become pregnant.

If your partner can get pregnant, use a condom during sex while taking this medication and for at least 1 year the last dose.

Talk to your care team before breastfeeding. Changes to your treatment plan may be needed.

Do not handle this medication if you are breastfeeding.

This medication may cause infertility. Talk to your care team if you are concerned about your fertility.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Hemolytic anemia—unusual weakness or fatigue, dizziness, headache, trouble breathing, dark urine, yellowing skin or eyes
  • Infection—fever, chills, cough, sore throat, wounds that don't heal, pain or trouble when passing urine, general feeling of discomfort or being unwell
  • Painful swelling, warmth, or redness of the skin, blisters or sores
  • Unusual bruising or bleeding

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Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

  • Constipation
  • Dry skin
  • Headache
  • Nausea

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children and pets.

Store between 20 and 25 degrees C (68 and 77 degrees F). Keep the container tightly closed. Store any broken or half tablets in the original container. Use broken or half tablets within 3 months. Get rid of any unused medication after the expiration date.

To get rid of medications that are no longer needed or have expired:

  • Take the medication to a medication take-back program. Check with your pharmacy or law enforcement to find a location.
  • If you cannot return the medication, ask your pharmacist or care team how to get rid of this medication safely.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

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Note: Introduction and Additional Common Questions written and medically approved by Cleveland Clinic professionals.

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