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Hydroxyurea (Systemic)

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Hydroxyurea (Systemic)

US Brand Names

• Hydrea

• Droxia

Canadian Brand Names

• Hydrea


Hydroxyurea (hye-DROX-ee-yoo-REE-ah) belongs to the group of medicines called antimetabolites. It is used to treat some kinds of cancer and to prevent painful episodes associated with sickle cell anemia.

Hydroxyurea seems to interfere with the growth of cancer cells, which are eventually destroyed. Since the growth of normal body cells may also be affected by hydroxyurea, other effects will also occur. Some of these may be serious and must be reported to your doctor. Other effects may not be serious but may cause concern. Some effects may not occur for months or years after the medicine is used.

When used in sickle cell anemia, hydroxyurea appears to increase the flexibility of sickled cells.

Before you begin treatment with hydroxyurea, you and your doctor should talk about the good this medicine will do as well as the risks of using it.

Hydroxyurea is available only with your doctor's prescription, in the following dosage form:


    • Capsules (U.S. and Canada)

Special Considerations

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 hydroxyurea, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to hydroxyurea.


Tell your doctor if you are pregnant or if you intend to have children. There is a chance that this medicine may cause birth defects if either the male or female is taking it at the time of conception or if it is taken during pregnancy. Studies have shown that hydroxyurea causes birth defects in animals. In addition, many cancer medicines may cause sterility. Although sterility seems to be only temporary with this medicine, the possibility should be kept in mind.

Be sure that you have discussed this with your doctor before taking this medicine. It is best to use some kind of birth control while you are taking hydroxyurea. Tell your doctor right away if you think you have become pregnant while taking hydroxyurea.


Hydroxyurea passes into human breast milk. Tell your doctor if you are breast-feeding or if you intend to breast-feed during treatment with this medicine. Because hydroxyurea may cause serious side effects, breast-feeding is not recommended while you are taking it.


Side effects may be likely to occur in children, who may be more sensitive to the effects of hydroxyurea.

Older adults

Side effects may be more likely to occur in the elderly, who may be more sensitive to the effects of hydroxyurea.

Other medicines

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 hydroxyurea, it is especially important that your health care professional know if you are taking any of the following:

    • Amphotericin B by injection (e.g., Fungizone) or

    • Antithyroid agents (medicine for overactive thyroid) or

    • Azathioprine (e.g., Imuran) or

    • Chloramphenicol (e.g., Chloromycetin) or

    • Colchicine or

    • Cyclophosphamide (e.g., Cytoxan) or

    • Flucytosine (e.g., Ancobon) or

    • Ganciclovir (e.g., Cytovene) or

    • Interferon (e.g., Intron A, Roferon-A) or

    • Mercaptopurine (e.g., Purinethol) or

    • Methotrexate (e.g., Rheumatrex) or

    • Plicamycin (e.g., Mithracin) or

    • Zidovudine (e.g., AZT, Retrovir) or

    • If you have ever been treated with x-rays or other cancer medicines-Hydroxyurea may increase the effects of these medicines or radiation therapy on the blood

    • Probenecid (e.g., Benemid) or

    • Sulfinpyrazone (e.g., Anturane)-Hydroxyurea may increase the amount of uric acid in the blood. Since these medicines are used to lower uric acid levels, they may not be as effective in patients taking hydroxyurea

    • Abacavir (e.g., ABC, Ziagen) or

    • Abacavir/Lamivudine/Zidovudine (e.g., Trizivir) or

    • Amprenavir (e.g., Agenerase) or

    • Delavirdine (e.g., Rescriptor) or

    • Didanosine (e.g., ddI, Videx) or

    • Efavirenz (e.g., Sustiva) or

    • Indinavir (e.g., Crixivan) or

    • Lamivudine (e.g., 3TC, Epivir) or

    • Lamivudine/Zidovudine (e.g., Combivir) or

    • Lopinavir/Ritonavir (e.g., Kaletra) or

    • Nelfinavir (e.g., Viracept) or

    • Nevirapine (e.g., Viramune) or

    • Ritonavir (e.g., Norvir) or

    • Saquinavir (e.g., Fortovase) or

    • Saquinavir mesylate (e.g., Invirase) or

    • Stavudine (e.g. D4T, Zerit) or

    • Zalcitabine (e.g., ddC, HIVID) or

    • Zidovudine (e.g., AZT, Retrovir, ZDV)-Hydroxyurea may increase the effects of these medicines on the liver, pancreas, and nerves

Other medical problems

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

    • Anemia or

    • Leukopenia or

    • Neutropenia or

    • Thrombocytopenia-May worsen and affect the decision to continue therapy

    • Chickenpox (including recent exposure) or

    • Herpes zoster (shingles)-Risk of severe disease affecting other parts of the body

    • Gout or

    • Kidney stones-Hydroxyurea may increase levels of uric acid in the body, which can cause gout or kidney stones

    • Infection (especially AIDS or HIV)-Hydroxyurea may decrease your body's ability to fight infection or cause serious liver, pancreas, or peripheral nerve reactions with certain specific HIV treatments

    • Kidney disease-Effects may be increased because of slower removal of hydroxyurea from the body


Take hydroxyurea only as directed by your doctor . Do not use more or less of it, and do not use it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Taking too much may increase the chance of side effects, while taking too little may not improve your condition.

For patients who cannot swallow the capsules :

    • The contents of the capsule may be emptied into a glass of water and then taken immediately. Some powder may float on the surface of the water, but that is just filler from the capsule.

This medicine is sometimes given together with certain other medicines. If you are using a combination of medicines, make sure that you take each one at the right time and do not mix them. Ask your health care professional to help you plan a way to take your medicine at the right times.

While you are using this medicine, your doctor may want you to drink extra fluids so that you will pass more urine. This will help prevent kidney problems and keep your kidneys working well.

This medicine commonly causes nausea, vomiting, and diarrhea. However, it is very important that you continue to use the medicine, even if you begin to feel ill. Ask your health care professional for ways to lessen these effects.

If you vomit shortly after taking a dose of hydroxyurea, check with your doctor. You will be told whether to take the dose again or to wait until the next scheduled dose.


The dose of hydroxyurea will be different for different patients. The dose that is used may depend on a number of things, including what the medicine is being used for, the patient's weight, and whether or not other medicines are also being taken. If you are taking hydroxyurea at home, follow your doctor's orders or the directions on the label . If you have any questions about the proper dose of hydroxyurea, ask your doctor.

Missed dose

If you miss a dose of this medicine, do not take the missed dose at all and do not double the next one. Instead, go back to your regular dosing schedule and check with your doctor.


To store this medicine:

    • Keep out of the reach of children.

    • Store away from heat and direct light.

    • Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.

    • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.


It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.

While you are being treated with hydroxyurea, and after you stop treatment with it, do not have any immunizations (vaccinations) without your doctor's approval . Hydroxyurea may lower your body's resistance and there is a chance you might get the infection the immunization is meant to prevent. In addition, other persons living in your household should not take oral polio vaccine since there is a chance they could pass the polio virus on to you. Also, avoid persons who have recently taken oral polio vaccine. Do not get close to them and do not stay in the same room with them for very long. If you cannot take these precautions, you should consider wearing a protective face mask that covers the nose and mouth.

Hydroxyurea can temporarily lower the number of white blood cells in your blood, increasing 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 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.

Side Effects

Along with their needed effects, medicines like hydroxyurea can sometimes cause unwanted effects such as blood problems and other side effects. These and others are described below. Also, because of the way these medicines act on the body, there is a chance that they might cause other unwanted effects that may not occur until months or years after the medicine is used. These delayed effects may include certain types of cancer, such as leukemia. Ask your health care professional for ways to lessen these effects.

Although not all of these side effects may occur, if they do occur they may need medical attention.

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

More common

Cough or hoarseness; fever or chills; lower back or side pain; painful or difficult urination.

Less common

Black, tarry stools; blood in urine or stools; pinpoint red spots on skin; unusual bleeding or bruising.

Check with your doctor as soon as possible if any of the following side effects occur:

Less common

Blackening of fingernails and toenails; sores in mouth and on lips.


Confusion; convulsions (seizures); difficulty in urination; dizziness; hallucinations (seeing, hearing, or feeling things that are not there); headache; joint pain; swelling of feet or lower legs.

Symptoms of overdose

Scaling of skin on hands and feet; severe darkening of skin color; soreness; sores in mouth and on lips; swelling of palms and soles of feet; violet flushing of the skin.

Other 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

Diarrhea; drowsiness; loss of appetite; nausea or vomiting.

Less common

Constipation; redness of skin at place of irradiation; skin rash and itching.

Hydroxyurea may cause temporary loss of hair in some people. After treatment has ended, normal hair growth should return, although the new hair may be a slightly different color or texture.

After you stop taking hydroxyurea, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it. During this period of time check with your doctor as soon as possible if you notice any of the following side effects:

Black, tarry stools; blood in urine; cough or hoarseness; fever or chills; lower back or side pain; painful or difficult urination; pinpoint red spots on skin; unusual bleeding or bruising.

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

July 09, 2002

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