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Generic name: hydroxyurea [hye-DROX-ee-yoo-REE-a]
The brand names are: Droxia, Hydrea, Siklos, and Mylocel.
Drug class: antimetabolites

What is Siklos?

Siklos can be used for treating chronic myeloid leukemia, ovarian cancer, and certain forms of skin cancer (squamous cell cancer of the neck and head).

Siklos can also be used to lessen pain and blood transfusions for those suffering from sickle-cell anemia. The medicine is not effective in curing sickle cell anemia.Siklos could be used for other purposes that are not mentioned in this guide.

Side effects of Siklos

Contact a medical professional immediately in the event that you exhibit warning signs of an allergic reaction, such as symptoms of hives, breathing difficulties, and swelling of your lips, face, or tongue.

Siklos may cause serious side effects. Contact your doctor immediately if you experience:

  • Numbness, tingling, as well as burning or numbness in your feet or hands;
  • Red discoloration or numbness of the skin;
  • Skin wounds, open sores, or ulcers
  • Suddenly experiencing chest discomfort, wheezing, a dry cough, and feeling short of breath;
  • Low blood cell counts low blood cell counts—fever chills, tiredness, mouth sores, simple bleeding, unusual bruising of the white skin, cold fingers and toes, feeling lightheaded or
  • Indications of pancreas or liver issues: loss of appetite, upper stomach discomfort (that could be aggravated by back pain), nausea or vomiting, fast heart rate, and dark urine yellowing of the eyes (yellowing on the eyes or skin).

Common negative side effects of Siklos could include:

  • Loss of appetite, nausea;
  • Constipation, diarrhea;
  • Low blood cell count;
  • Bleeding
  • Mouth sores.

This list does not constitute a comprehensive overview of potential adverse reactions; others could occur. Please consult your physician for advice regarding medical effects; additionally, any symptoms can be reported directly to FDA at 1-800-FDA-1088.

Similar or related drugs

Hydroxyurea, vitamin E, Hydrea, Endari, glutamine, and Oxbryta


Men and women who use Siklos must use birth control to avoid pregnancy. The use of Siklos by either parent can result in birth defects.Utilizing Siklos could increase the chances of developing other kinds of cancers, like leukemia and skin cancer. Protect yourself by wearing protective clothes and applying sunscreen whenever you're outdoors.

Siklos could affect the immune system. Contact your doctor immediately in case you are suffering from an illness that causes chills, fever, body aches, severe fatigue, shortness of breath, and bruising. You may also experience unusual bleeding.

Prior to use this drug

It is not recommended to make use of Siklos in case you have an allergy to it.

Speak to your doctor if you were ever diagnosed with:

  • Kidney disease (or if you're taking dialysis)
  • The liver condition;
  • An ulcer or a cut on your leg.
  • HIV, also known as AIDS (especially in the event that you take antiviral medications),
  • Excessive levels of uric acid in your blood.
  • Treatment with interferon, chemotherapy, or radiation

Utilizing Siklos can increase the chance of developing other forms of leukemia or cancer. Consult your doctor regarding your risk.

Siklos may harm an unborn baby. Both females and males taking this medication must use birth control to stop the pregnancy. The use of this medication by any parent could result in birth defects.

  • If you're a female, take contraceptives for a minimum of 6 months following your most recent dose of Siklos.
  • If you're a man, take the birth control pill for at least one year from the date of the most recent dosage (6 months if taking Siklos).
  • Inform your doctor immediately when you notice a pregnancy during the time that one of the mothers or fathers is taking this medicine.

This medication can impact the fertility (ability to have children) of men. It is nevertheless important to utilize birth control since Siklos can harm the child in the event of a pregnancy.It is not recommended to breastfeed while you take Siklos.Adults who are older may have a greater sensitivity to the effects of this medication.

How to take Siklos?

Follow the directions on the prescription label and review all medication guides and instructions sheets. Your doctor may alter your dosage. Make sure you take the medicine precisely as directed.Siklos is typically taken once every day at the exact same time, either with or without food. Take the pill in its entirety by drinking a glass of water.

Wash your hands thoroughly before and after handling Siklos and the bottles that contain the pills. To protect yourself, use disposable gloves while dealing with pills.Do not take the Siklos capsule or crush or chew on a tablet. Don't use the broken tablet. The medication from broken or crushed pills could be hazardous when it is absorbed into your mouth, eyes, nose, or even your body. If this occurs, clean your skin using soap and water or wash your eyes in water.

If any of the powders from a broken pill spill, clean it up at once using a moist paper towel. Then, put the towel in a plastic bag that is sealed so that pets and children can't access it.

Your doctor might also advise you to take a folic acid supplement. Be sure to follow the dosing guidelines cautiously.Siklos can lower your blood cell counts. Your blood must be analyzed frequently. Your treatment for cancer could be delayed, depending on the results.

The medicine could affect the results of certain tests. Be sure to inform any doctor treating patients that you're using Siklos.Keep the bottle at room temperature, free of heat and moisture. Close the bottle when not being used.

What happens if I miss a dose?

Do not take the medicine for as long as you can. However, do not take any missed doses if you are nearing the time to take the next dose. Don't have two doses at one time.Refill your prescription prior to the time that you are out of medication completely.

What happens if I overdose?

For medical emergencies, seek emergency medical attention or contact the Poison Help Line toll-free at 1-800-222-1222.

Some symptoms of overdose include tiredness, mouth sores, and swelling that causes pain, as well as discoloration of your feet and hands.

What should be avoided?

The use of Siklos could increase the chances of developing skin cancer. Avoid exposure to the sun and tanning beds. Wear appropriate clothing and sunblock (SPF 30 or more) while you're outdoors.

Don't receive a "live" vaccine while using Siklos, as you may get a severe illness. The live vaccines are measles, rubella, mumps (MMR), and rotavirus. Yellow fever, typhoid varicella (chickenpox), shingles, and the nasal influenza (influenza) vaccination.Be careful around those who are sick or suffering from infections. Inform your doctor immediately when you begin to show symptoms of an infection.

Don't handle Siklos medication or the bottle if you are not wearing skin protection (disposable gloves).

Interaction with other drugs

Certain medicines may increase the risk of having serious adverse reactions while you are taking Siklos. Inform your physician if you're taking antiviral medication or interferon.

Other drugs can also impact Siklos, such as medications that are prescribed and available over the counter, vitamins, and herbal products. Discuss with your doctor your current medications and any medication you begin or stop taking.



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