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Overview: Hydroxyurea is a medication used to treat sickle cell anemia and certain cancers. The most common side effects include digestive upset and low blood cell counts. Contact your health care provider right away if you develop an infection, bleeding, breathing problems, or skin sores while taking hydroxyurea. It comes in several forms, including capsules, tablets, and a liquid.

Uses

What is hydroxyurea used for?

Hydroxyurea is commonly used for the following conditions. These uses may vary depending on the specific hydroxyurea product prescribed. 

Hydroxyurea may also be used for other conditions as determined by your health care provider.

How does hydroxyurea work (mechanism of action)?

Hydroxyurea works by stopping certain cells from making DNA. For sickle cell disease, this is thought to reduce the number of abnormal (sickle) cells and improve symptoms. For certain cancers, hydroxyurea may help by slowing or stopping the growth of cancer cells.

How is hydroxyurea supplied (dosage forms)?

Brands and other names

  • Droxia
  • Hydrea
  • Siklos
  • Xromi

Dosage forms and strengths

  • 200 mg oral capsules
  • 300 mg oral capsules
  • 400 mg oral capsules
  • 500 mg oral capsules
  • 100 mg/mL oral solution
  • 100 mg oral tablets
  • 1,000 mg oral tablets

How should I store hydroxyurea?

Oral Capsules and Oral Tablets. Hydroxyurea capsules and tablets should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place with the lid tightly closed.

Oral Liquid. Hydroxyurea liquid should be stored in the refrigerator, at temperatures between 35 F and 46 F (2 C and 8 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C), for up to 72 hours. Do not freeze it. Keep the lid tightly closed between doses. After you open the bottle, the medicine should be used or thrown away within 12 weeks.

Side Effects

What are the most common side effects of hydroxyurea?

The most common side effects of hydroxyurea are listed below. These side effects may vary depending on the condition that is being treated. Tell your health care provider if you have any of these side effects that bother you.

  • Blood disorders (see below)
  • Nausea, diarrhea, or constipation
  • Loss of appetite
  • Mouth sores
  • Infections
  • Headache
  • Dry skin

There may be other side effects of hydroxyurea that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of hydroxyurea?

While less common, the most serious side effects of hydroxyurea are described below, along with what to do if they happen.

Severe Allergic Reactions. Hydroxyurea may cause allergic reactions, which can be serious. Stop taking hydroxyurea and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Blood Disorders. Hydroxyurea can cause blood disorders, such as low white blood cell levels (leukopenia), low platelet levels (thrombocytopenia), anemia, hemolytic anemia, and macrocytosis. Keep all appointments to have your blood checked while you are taking this medicine. Call your health care provider or get help right away if you have any of the following symptoms of blood disorders while taking hydroxyurea.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infection
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Fast or abnormal heartbeat
  • Blood in your pee

Skin Ulcers or Gangrene. Hydroxyurea can cause serious skin problems, such as sores, leg ulcers, or gangrene (damaged, dead skin tissue). Past or current use of interferon treatment may raise the risk. If you develop any sores on your skin, stop taking hydroxyurea and tell your health care provider right away. 

Cancer. Taking hydroxyurea for a long time can cause a new or second cancer to develop, such as leukemia (a type of blood cancer) or skin cancer. Protect your skin from the sun by wearing sunscreen and limit sun exposure. Tell your health care provider about any new symptoms, lumps, or unusual skin changes.

Lung Inflammation. Hydroxyurea can cause inflammation in your lungs, also called interstitial lung disease or pneumonitis. This can be serious and life-threatening. Get emergency help if you have trouble breathing. You may also have a cough, fever, or chest pain.

Warnings & Precautions

Who should not take hydroxyurea?

Allergies to Ingredients. People who are allergic to any of the following should not take hydroxyurea.

  • Droxia
  • Hydrea
  • Hydroxyurea
  • Siklos
  • Xromi
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific hydroxyurea products they stock.

What should I know about hydroxyurea before taking it?

Do not take hydroxyurea unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share hydroxyurea with other people, even if they have the same condition as you. It may harm them.

Keep hydroxyurea out of the reach of children. Since hydroxyurea oral liquid can be kept in a refrigerator, take special precautions to keep it away from children who also use the refrigerator. 

Do not shake hydroxyurea liquid. To measure your dose, use one of the two oral syringes that come with the medicine. Ask your pharmacist which size oral syringe is the right size for your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. 

Always wear gloves and wash your hands before and after touching this medicine. Avoid touching hydroxyurea, especially any oral tablets or capsules that are broken, open, or crushed. Do not open hydroxyurea oral capsules. For more details on how to safely handle or dispose of hydroxyurea, talk to your health care provider.

Hydroxyurea can cause harm to a fetus. If you can become pregnant, use effective birth control while taking hydroxyurea and for at least six months after your last dose. If you are able to get your partner pregnant, use effective birth control while taking hydroxyurea. You may need to continue using effective birth control for some time after your last dose of hydroxyurea. Talk with your health care provider about your birth control options and how long you should use it after finishing this medicine.

Hydroxyurea may make it hard for you to get your partner pregnant. Talk with your health care provider if this is a concern for you.

People who are 65 and older can be at greater risk of some side effects from hydroxyurea. Talk to your health care provider about your risks if you are in this age group.

What should I tell my health care provider before taking hydroxyurea?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if hydroxyurea is right for you.

In particular, make sure that you discuss any of the following.

Vaccines. Talk with your health care provider about any vaccines that you may need. You should not receive certain vaccines right before or while taking hydroxyurea. Tell your health care provider about any vaccines you have recently received or have scheduled.

Continuous Glucose Monitor. Hydroxyurea may cause falsely high blood sugar results in people using a continuous glucose monitor (CGM) to measure their blood sugar levels. Tell your health care provider if you use a CGM. To help prevent problems with managing your blood sugar, they may recommend other ways to monitor your blood sugar while taking hydroxyurea.

Other Medicines and Supplements. Hydroxyurea may interact with other medicines and supplements. Before taking hydroxyurea, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Liver problems
  • Kidney problems
  • HIV
  • High blood levels of uric acid
  • Skin ulcers or wounds
  • Received radiation treatment or used an interferon medicine in the past

Pregnancy. Hydroxyurea can cause harm to a fetus. Your health care provider may require a negative pregnancy test before you can start taking hydroxyurea. If you are able to get pregnant, you should use effective birth control while you are taking hydroxyurea and for at least six months after your last dose. Tell your health care provider if you are pregnant, think you are pregnant, or plan to become pregnant.

Breastfeeding. Do not take hydroxyurea while you are breastfeeding. Hydroxyurea can pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does hydroxyurea interact with foods or drinks?

There are no known interactions between hydroxyurea and foods or drinks. Hydroxyurea oral liquid (Xromi) should be taken with or after meals, ideally at the same time and in the same way each day.

It is unknown if drinking alcohol will affect hydroxyurea, but both hydroxyurea and alcohol can raise your risk of bleeding. Heavy drinking can slow your immune response and make it harder for your body to fight cancer. It is best to limit the amount of alcohol you drink while taking this medicine.

Does hydroxyurea interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking hydroxyurea. 

  • A medicine to treat or prevent HIV or AIDS
  • An interferon, such as interferon beta-1a (Avonex, Rebif, others), interferon gamma-1b (Actimmune), or peginterferon alpha-2a (Pegasys), which is a medicine that helps your immune system

This may not be a complete list of medicines that can interact with hydroxyurea. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally take too much hydroxyurea?

If you or someone else has taken too much hydroxyurea, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of hydroxyurea?

If you miss a dose of hydroxyurea, take it as soon as possible on the same day. If you cannot take it that day, skip the missed dose and continue with your next dose as usual. Do not take extra doses to make up for a missed dose. Ask your health care provider if you are unsure what to do after a missed dose.