Hydroxyurea is used to treat chronic myeloid leukemia, ovarian cancer, and certain types of skin cancer (squamous cell cancer of the head and neck).

Hydroxyurea is also used to reduce pain episodes and the need for blood transfusions in people with sickle cell anemia. Hydroxyurea will not cure sickle cell anemia.

Hydroxyurea may also be used for purposes not listed in this medication guide.

Both men and women using hydroxyurea should use birth control to prevent pregnancy. The use of hydroxyurea by either parent may cause birth defects.

Using hydroxyurea may increase your risk of developing other types of cancer, such as leukemia or skin cancer. Wear protective clothing and use sunscreen when you are outdoors.

Hydroxyurea can weaken your immune system. Call your doctor at once if you have a fever, chills, body aches, extreme tiredness, shortness of breath, bruising, or unusual bleeding.

Hydroxyurea comes as a capsule and tablet to take by mouth. It is usually taken once a day with a glass of water. When hydroxyurea is used to treat certain types of cancer, it may be taken once every third day. Take hydroxyurea at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take hydroxyurea exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor may need to delay your treatment or adjust your dose of hydroxyurea depending on your response to treatment and any side effects that you may experience. Talk to your doctor about how you are feeling during your treatment. Do not stop taking hydroxyurea without talking to your doctor.

Your doctor will probably tell you to take another medication, folic acid (a vitamin), to decrease some of the side effects of this medication. Take this medication exactly as directed.

Swallow the capsules whole; do not split, chew, or crush them.

The hydroxyurea 1,000-mg tablets (Siklos) are scored so that they can easily be split into halves or quarters to provide smaller doses. Do not break the hydroxyurea 100-mg tablets into smaller parts. Your doctor will tell you how to break the tablets and how many tablets or parts of a tablet you should take.

If you are unable to swallow hydroxyurea tablets or portion(s) of tablets, you may dissolve your dose in water. Place your dose in a teaspoon and add a small amount of water. Wait about 1 minute to allow the tablet(s) to dissolve, then swallow the mixture right away.

You should wear rubber or latex gloves when you handle the capsules or tablets so that your skin does not come into contact with the medication. Wash your hands with soap and water before and after you touch the bottle or medication. If hydroxyurea gets into your eyes, immediately flush your eyes with water for at least 15 minutes. If the powder from a capsule or tablet spills, wipe it up immediately with a damp disposable towel. Then place the towel in a closed container, such as a plastic bag, and throw it away in a trash can that is out of the reach of children and pets. Clean the spill area using a detergent solution followed by clean water.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Hydroxyurea is usually taken once per day at the same time of day, with or without food. Swallow the pill whole with a glass of water.

Wash your hands before and after you handle hydroxyurea or the bottle that contains the pills. For best protection, wear disposable gloves when handling the pills.

Do not open the hydroxyurea capsule or crush or chew a tablet. Do not use a broken pill. The medicine from a crushed or broken pill can be dangerous if it gets in your eyes, mouth, or nose, or on your skin. If this occurs, wash your skin with soap and water or rinse your eyes with water.

If any powder from a broken pill is spilled, wipe it up at once with a damp paper towel and throw the towel away in a sealed plastic bag where children and pets cannot get to it.

Your doctor may also want you to take a folic acid supplement. Follow dosing instructions very carefully.

Hydroxyurea can lower your blood cell counts. Your blood will need to be tested often. Your cancer treatments may be delayed based on the results.

This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using hydroxyurea.

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

You should not use hydroxyurea if you are allergic to it.

Tell your doctor if you have ever had:

• kidney disease (or if you are on dialysis);

• liver disease;

• a wound or ulcer on your leg;

• HIV or AIDS (especially if you take antiviral medicine);

• high levels of uric acid in your blood; or

• treatment with an interferon, chemotherapy, or radiation.

Using hydroxyurea may increase your risk of developing other types cancer or leukemia. Talk with your doctor about your specific risk.

Hydroxyurea can harm an unborn baby. Both men and women using this medicine should use birth control to prevent pregnancy. The use of this medicine by either parent may cause birth defects.

• If you are a woman, keep using birth control for at least 6 months after your last dose of hydroxyurea.

• If you are a man, keep using birth control for at least 1 year after your last dose (6 months if you took Siklos).

• Tell your doctor right away if a pregnancy occurs while either the mother or the father is using this medicine.

This medicine may affect fertility (ability to have children) in men. However, it is important to use birth control because hydroxyurea may harm the baby if a pregnancy does occur.

You should not breastfeed while you are taking hydroxyurea.

Older adults may be more sensitive to the effects of this medicine.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Get your prescription refilled before you run out of medicine completely.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include drowsiness, mouth sores, and swelling with pain and purple discoloration in your hands and feet.

Keep this medication in the container it came in, tightly closed, and out of reach of children and pets. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Broken 1,000-mg tablets must be stored in the container and must be used within 3 months.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

Unless your doctor tells you otherwise, continue your normal diet.

Using hydroxyurea may increase your risk of developing skin cancer. Avoid exposure to sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

Do not receive a "live" vaccine while using hydroxyurea, or you could develop a serious infection. Live vaccines include measles, mumps, rubella (MMR), rotavirus, typhoid, yellow fever, varicella (chickenpox), zoster (shingles), and nasal flu (influenza) vaccine.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

Do not handle hydroxyurea pills or the medicine bottle without skin protection (disposable gloves).

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Hydroxyurea may cause serious side effects. Call your doctor at once if you have:

• numbness, tingling, or burning pain in your hands or feet;

• skin numbness or purple discoloration;

• skin ulcers or open sores;

• sudden chest pain, wheezing, dry cough, feeling short of breath;

• low blood cell counts--fever, chills, tiredness, mouth sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed; or

• signs of liver or pancreas problems--loss of appetite, upper stomach pain (that may spread to your back), nausea or vomiting, fast heart rate, dark urine, jaundice (yellowing of the skin or eyes).

Common side effects of hydroxyurea may include:

• loss of appetite, nausea;

• constipation, diarrhea;

• low blood cell counts;

• bleeding; or

• mouth sores.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Some medicines can increase your risk of serious side effects while taking hydroxyurea. Tell your doctor if you are also using antiviral medicine or an interferon.

Other drugs may affect hydroxyurea, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking hydroxyurea.

Do not let anyone else take your medication. People who are not taking hydroxyurea should avoid touching the medication or the bottle that contains the medication.

Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.