What is Hydroxyurea: Uses, Warnings & Interactions

Take this medicine as directed. The dose may need to be changed several times during treatment.

Please read the Medication Guide that comes with this medicine.

The doctor may prescribe folic acid supplements along with this drug. Take doses as prescribed.

Hydroxyurea can be taken with or without food, but always take it the same way.

How to take hydroxyurea capsules:

• Hydroxyurea capsules are for cancer treatment only.

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

• Store hydroxyurea capsules at room temperature.

How to take hydroxyurea tablets:

• Hydroxyurea tablets (Siklos) are for sickle cell treatment only.

• Use only in adults and children 2 years of age and older.

• Take only one dose daily at the same time each day. 

• Swallow the tablet whole with a glass of water.

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

• Hydroxyurea tablets have score lines to allow the tablet to be divided into smaller doses. The 100 mg tablet can be divided into two smaller doses of 50 mg each. The 1,000 mg tablet can be divided into smaller doses of 250 mg, 500 mg, or 750 mg.

• If you don’t know how to divide a tablet, ask a pharmacist to show you the proper procedure.

• Store hydroxyurea tablets at room temperature.

• Throw away any unused medicine after three months.

How to take hydroxyurea oral solution:

• Hydroxyurea oral solution (Xromi) is used only for sickle cell treatment.

• Hydroxyurea solution is used only in children as young as 6 months.

• Please read and follow the Instructions for Use that come with this medicine.

• Administer only one dose daily at the same time each day. 

• Do not shake the bottle before measuring a dose.

• Use only the calibrated oral syringe that comes with this medicine to measure a dose. Do not use any other measuring device.

• Use the 3 mL oral syringe for doses less than 3 mL.

• Use the 10 mL oral syringe for doses larger than 3 mL. 

• Place the syringe against the inside of the child’s cheek to give a dose.

• Have the child drink water right after the dose.

• Wash the oral syringe immediately after each dose. Immerse the syringe in water and push the plunger up and down several times. Let the oral syringe dry completely.

• Store hydroxyurea solution in the refrigerator. Do not freeze.

• Throw away any remaining medicine 12 weeks after first opening the bottle.

How safely administer hydroxyurea:

• Hydroxyurea is a hazardous drug that must be handled with caution.

• Do not get this drug on the skin or other parts of the body when administering doses. Never touch the bottle or the medicine with bare hands.

• Before touching the bottle or giving a dose, wash your hands with soap and water. Then, put on disposable gloves.

• To prevent contamination, always place tablets or capsules in the bottle cap. Do not put them on any other surface.

• To prevent spills, never open a hydroxyurea capsule.

• Remove disposable gloves by carefully turning them inside out while taking them off. Do not touch the outside of the glove.

• When finished giving a dose, wash your hands with soap and water again.

• Ask the pharmacist how to safely dispose of the empty bottle or any leftover medicine.

How to safely clean a spill:

• If any hydroxyurea residue, powder, or liquid gets on surfaces, wipe it up immediately with a plastic-backed absorbent pad or, if one is not available, a damp disposable towel. Place the pad or towel immediately in a plastic bag and throw it away. Wash the area thoroughly with detergent or bleach. Rinse the area with water. Do not touch anything else until disposing of your gloves. 

• If any hydroxyurea residue, powder, or liquid gets on your skin, wash the skin right away with soap and water. 

• If any hydroxyurea residue, powder, or liquid gets into your eyes, rinse them with water or an isotonic eyewash for at least 15 minutes.

Take a dose as soon as you remember, but only on the same day.

If it’s the next day, skip the missed dose.

Take the next dose at its regularly scheduled time.

NEVER take extra medicine to make up for a missed dose.

This medicine is not right for everyone. 

Do not use it if you have had an allergic reaction to hydroxyurea.

Hydroxyurea is a risky drug. Treatment requires frequent monitoring and blood tests, sometimes every two weeks. Keep all appointments. Tell the doctor about all side effects that you experience. 

Tell all doctors, dentists, and other healthcare providers that you are using this medicine. Hydroxyurea can affect the results of several important medical tests.

Keep hydroxyurea in a child-proof sealed container that is out of the reach of children. Never share your medicine with anyone.

Before starting hydroxyurea treatment, tell the prescriber if you are pregnant, breastfeeding, or have:

• Kidney problems

• Liver problems

• An HIV infection

• High levels of uric acid in the blood (hyperuricemia)

• Leg wounds or ulcers

Tell the doctor if you’re using a continuous glucose monitor.

Hydroxyurea can cause serious problems including:

• Low blood cell counts (anemia)

• Low white blood cell counts increasing the risk of infection

• Rapid destruction of red blood cells (hemolytic anemia)

• Cancer, particularly leukemia or skin cancer (due to long-term use)

• Skin sores or gangrene (in people with myeloid leukemia)

• Lung damage (interstitial lung disease)

• Fertility problems in men

Hydroxyurea can harm an unborn baby. It can cause birth defects when taken during pregnancy or when taken by either the male or female partner at conception.

• Women should avoid taking hydroxyurea when pregnant.

• Women should avoid getting pregnant while taking hydroxyurea. 

• Women and men taking hydroxyurea should use appropriate birth control when taking hydroxyurea and for six months after the drug has been stopped.

• Women should immediately inform the prescriber if they become pregnant or think they’re pregnant. 

Women taking hydroxyurea should avoid breastfeeding.

Hydroxyurea can make people more vulnerable to infections. It can also cause unusual bleeding or bruising episodes. Take precautionary steps to avoid infection or injury.

When using hydroxyurea over a long time, take precautions to protect the skin from sunlight. Wear sunscreen. Do not use sunlamps or tanning beds.

People who have had radiation treatment may experience a recurrence of skin redness in the radiated area.

To avoid potentially hazardous drug interactions, tell the doctor about all the medicines and supplements you take, particularly: 

• Interferon

• HIV/AIDS medications

Tell the doctor about any recent or upcoming vaccines. Live vaccines may cause severe infections in people taking hydroxyurea.

Tell other doctors about hydroxyurea before they prescribe new medications.