Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Droxia
  2. Hydrea
  3. Siklos

Canadian Brand Name

  1. APO-hydroxyUREA
  2. Mylan-hydroxyUREA

Descriptions


Hydroxyurea is used to treat cancer of the white blood cells called chronic myeloid leukemia (CML). It may also be given together with radiation treatment for head and neck cancer (advanced squamous cell cancer). Hydroxyurea interferes with the growth of cancer cells, which are eventually destroyed by the body.

Hydroxyurea is used to prevent painful episodes and reduce the need for blood transfusions in patients with sickle cell anemia. It works by making the red blood cells more flexible.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Tablet
  • Capsule

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of Droxia® or Hydrea® in the pediatric population. Safety and efficacy have not been established.

Appropriate studies have not been performed on the relationship of age to the effects of Siklos® in children younger than 2 years of age. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of Droxia® or Hydrea® in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving hydroxyurea.

No information is available on the relationship of age to the effects of Siklos® in geriatric patients.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Measles Virus Vaccine, Live
  • Mumps Virus Vaccine, Live
  • Rotavirus Vaccine, Live
  • Rubella Virus Vaccine, Live
  • Varicella Virus Vaccine, Live
  • Zoster Vaccine, Live

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Adenovirus Vaccine, Live
  • Bacillus of Calmette and Guerin Vaccine, Live
  • Cholera Vaccine, Live
  • Dengue Tetravalent Vaccine, Live
  • Didanosine
  • Ebola Zaire Vaccine, Live
  • Exagamglogene Autotemcel
  • Influenza Virus Vaccine, Live
  • Levoketoconazole
  • Lovotibeglogene Autotemcel
  • Methotrexate
  • Poliovirus Vaccine, Live
  • Smallpox Monkeypox Vaccine, Live Non-Replicating
  • Smallpox Vaccine
  • Stavudine
  • Typhoid Vaccine, Live
  • Yellow Fever Vaccine

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Anemia (low red blood cells), worsening of or
  • Bone marrow problems (eg, myelosuppression) or
  • HIV infection or
  • Leg ulcers or
  • Leukopenia (low number of white blood cells) or
  • Lung disease (eg, interstitial lung disease, pneumonitis, alveolitis) or
  • Thrombocytopenia (low number of platelets)—Use with caution. May make these conditions worse.
  • Kidney disease, severe or
  • Liver disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Proper Use

Use this medicine exactly as directed by your doctor. Do not use more of it, do not use it more often, and do not use it for a longer time than your doctor ordered.

This medicine comes with a Medication Guide and patient instructions. Read and follow the instructions carefully. Ask your doctor if you have any questions.

Your doctor may want you to take folic acid before starting treatment with this medicine.

Swallow the capsule or tablet whole. Do not crush, break, chew, or open it.

If you cannot swallow the tablet whole, you may dissolve it with a small quantity of water in a teaspoon for about 1 minute. Swallow the mixture right away, then drink a glass of water.

Hydroxyurea capsules and tablets should be handled with care. People who are not taking this medicine should avoid touching it. To decrease your chance of touching the medicine:

  • Wear disposable gloves when handling the bottle or medicine.
  • Wash your hands with soap and water before and after contact with the bottle or medicine.
  • Do not open the capsules or break the tablets. Avoid exposure to crushed, broken, or opened capsules or tablets.
  • If you touch an opened capsule or crushed tablet, wash your skin right away with soap and water.
  • If powder from the capsule or crushed tablets get into your eyes, rinse them with water or an isotonic eyewash for at least 15 minutes.
  • If powder from the capsule or broken tablet is spilled, wipe it up right away with a damp disposable towel. Place the towel and the empty capsule in a closed container, such as a plastic bag.
  • The area where the powder spilled should be cleaned 3 times using a detergent solution followed by clean water.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For cancer of the head and neck:
    • For oral dosage form (capsules):
      • Adults—Dose is based on body weight and must be determined by your doctor. The dose is 15 milligrams (mg) per kilogram (kg) of body weight per day, taken as a single dose. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
  • For chronic myelocytic leukemia (CML):
    • For oral dosage form (capsules):
      • Adults—Dose is based on body weight and must be determined by your doctor. The dose is 15 milligrams (mg) per kilogram (kg) of body weight per day, taken as a single dose. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
  • For sickle cell anemia:
    • For oral dosage form (capsules):
      • Adults—Dose is based on body weight and must be determined by your doctor. At first, the dose is 15 milligrams (mg) per kilogram (kg) of body weight per day, taken as a single dose. Your doctor may adjust your dose as needed. However, the dose is usually not more than 35 mg per kg of body weight per day.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults—Dose is based on body weight and must be determined by your doctor. At first, 15 milligrams (mg) per kilogram (kg) of body weight once a day. Your doctor may adjust your dose as needed.
      • Children 2 years of age and older—Dose is based on body weight and must be determined by your doctor. At first, 20 mg per kg of body weight once a day. Your doctor may adjust your dose as needed.
      • Children younger than 2 years of age—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Store the broken tablets in the bottle and use them within 3 months. Throw away any unused broken tablet after 3 months.

Precautions

It is very important that your doctor check your or your child's progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. If you are a woman who can get pregnant, your doctor may do tests to make sure you are not pregnant before starting this medicine. Women should use an effective form of birth control during treatment with this medicine and for at least 6 months after the last dose. Men should use an effective form of birth control during treatment and for at least 1 year for Droxia® and Hydrea® and at least 6 months for Siklos® after the last dose to prevent pregnancy in a sexual partner. If a pregnancy occurs while using the medicine, tell your doctor right away.

Hydroxyurea can temporarily lower the number of white blood cells in your blood which increases the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

  • If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

Check with your doctor right away if you have back, leg, or stomach pains, bleeding gums, chills, dark urine, difficulty breathing, fever, general body swelling, headache, loss of appetite, nausea or vomiting, nosebleeds, pale skin, sore throat, unusual tiredness or weakness, or yellowing of the eyes or skin. These may be symptoms of a blood problem called hemolytic anemia.

Using this medicine for a long time may increase your risk of developing leukemia (cancer of the blood) or skin cancer. Use a sunscreen and protective clothing to protect your skin. Talk to your doctor if you have concerns about this risk.

If you had radiation treatment in the past, Hydrea® may cause your skin to become very red when you have radiation again. Tell your doctor right away if you have darkening or reddening of the skin.

While you are being treated with hydroxyurea, do not have any immunizations (vaccinations) without your doctor's approval. Live virus vaccinations (eg, nasal flu virus vaccine) should not be given while you are using hydroxyurea.

This medicine may increase your risk of having lung or breathing problems (eg, interstitial lung disease). Check with your doctor right away if you develop a fever, cough, or trouble breathing while using this medicine.

Make sure any doctor or dentist who treats you knows that you are using this medicine. The results of some tests (eg, continuous glucose monitor) may be affected by this medicine.

Talk with your doctor before using this medicine if you plan to have children. Some men who use this medicine have become infertile (unable to have children).

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  1. Black, tarry stools
  2. blood in the urine or stools
  3. chills
  4. cough
  5. fever
  6. hoarseness
  7. lower back or side pain
  8. painful or difficult urination
  9. pale skin
  10. pinpoint red spots on the skin
  11. sore throat
  12. ulcers, sores, or white spots in the mouth
  13. unusual bleeding or bruising
  14. unusual tiredness or weakness

Less common

  1. Blackening of the fingernails and toenails
  2. trouble breathing

Rare

  1. Confusion
  2. dizziness
  3. headache
  4. joint pain
  5. seeing, hearing, or feeling things that are not there
  6. seizures
  7. swelling of the feet or lower legs

Incidence not known

  1. Back, leg, or stomach pains
  2. bleeding gums
  3. bleeding under the skin
  4. blisters on the skin
  5. bluish or pale color on the skin of the fingers or toes
  6. chest tightness
  7. coldness of the fingers or toes
  8. crater-like lesions on the skin
  9. dark urine
  10. drowsiness
  11. fast heartbeat
  12. general body swelling
  13. hives, itching, skin rash
  14. irritation
  15. itching, pain, redness, or swelling on the leg
  16. joint stiffness or swelling
  17. loss of appetite
  18. muscle spasms (tetany) or twitching seizures
  19. nausea
  20. nosebleeds
  21. numbness or tingling of the fingers or toes
  22. pain in the fingers or toes
  23. sore on the leg
  24. swelling of the eyelids, face, lips, hands, or feet
  25. trembling
  26. trouble swallowing
  27. vomiting
  28. weight loss
  29. yellowing of the eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Diarrhea
  2. dry skin

Less common

  1. Constipation
  2. redness of skin at the place of radiation
  3. weight gain

Incidence not known

  1. Absent, missed, or irregular menstrual periods
  2. bluish-brownish bands on the nails
  3. indigestion
  4. passing of gas
  5. stomach pain, fullness, or discomfort
  6. stopping of menstrual bleeding
  7. thinning or loss of hair

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Portions of this document last updated: April 01, 2024

Original article: https://www.mayoclinic.org/drugs-supplements/hydroxyurea-oral-route/side-effects/drg-20068109