Hydroxyurea Medications

Hydroxyurea Info

What Is Hydroxyurea?

Hydroxyurea is a synthetic, oral medication that belongs to the class of antimetabolite agents. It works by interrupting the growth of certain cells, especially those that divide quickly. In Hong Kong, hydroxyurea is available only with a prescription and is listed under the Pharmacy and Poisons Board’s controlled substances. The drug appears in products such as Hydrea.

Medications with Hydroxyurea

The principal product containing hydroxyurea in Hong Kong is Hydrea (hydroxyurea tablets). It is marketed in several strengths, most commonly 500 mg and 1 g tablets, and is sold under its generic name as well as the brand name Hydrea. The tablets are taken by mouth and are the typical formulation used for the conditions described below. Other combination tablets that include hydroxyurea are not currently registered in Hong Kong, so Hydrea remains the main option for patients prescribed this ingredient.

What Does Hydroxyurea Treat?

• Sickle-cell disease - Hydroxyurea helps reduce the frequency of painful crises by increasing the amount of fetal haemoglobin in red blood cells, which makes them less likely to sickle.
• Chronic myelogenous leukaemia (CML) - When used together with other cancer medicines, hydroxyurea can slow the growth of leukaemic cells.
• Polycythaemia vera - The drug lowers the excessive production of red blood cells, helping to keep blood thickness within safer limits.
• Essential thrombocythaemia - Hydroxyurea controls the over-production of platelets, lowering the risk of clot-related complications.

These uses are approved by the Hong Kong Department of Health. In some cases, clinicians may consider hydroxyurea for other blood-cell disorders, but such decisions are made on an individual basis.

How Hydroxyurea Works

Hydroxyurea interferes with the ability of cells to copy their DNA, which slows down the division of rapidly multiplying cells. By limiting this process, the drug reduces the number of abnormal blood cells that cause disease symptoms. In sickle-cell disease, the same action also allows the body to produce more fetal haemoglobin, which keeps red cells flexible. Effects usually become noticeable after several weeks of regular use, rather than instantly.

Safety Information

Common Side Effects

• Mild nausea or loss of appetite
• Temporary loss of hair or thinning of scalp hair
• Low-grade fever or tiredness
• Small bruises or easy bleeding from gums

These reactions are generally short-lasting and often improve as the body adjusts to the medication.

Serious Reactions

• Severe skin rash or swelling that spreads quickly
• Trouble breathing, wheezing, or throat tightness
• Sudden, unexplained bruising or bleeding, especially from the nose or gums
• Signs of infection such as persistent fever, chills, or pus-filled sores

If any of these occur, seek urgent medical help.

Who Should Be Cautious

• Pregnant or breastfeeding individuals should avoid hydroxyurea unless a doctor determines it is essential, because the drug can affect fetal development.
• People with severe kidney or liver impairment may need special monitoring.
• Those with a known allergy to hydroxyurea or any of its tablet ingredients should not use the medication.

Interaction Awareness

• Other chemotherapy agents - Hydroxyurea can add to the blood-suppressing effects of other cancer drugs.
• Antiviral medication (e.g., zidovudine) - Combined use may increase the risk of blood-cell suppression.
• Alcohol - Excessive drinking can worsen liver strain and increase the chance of nausea.
• Food - Hydroxyurea may be taken with or without food; however, a high-fat meal can delay absorption slightly.

For a complete list of potential interactions, refer to the detailed information supplied with each specific product.

What to Know Before Using

Store Hydrorea tablets in a cool, dry place away from direct sunlight and out of reach of children. The medication is generally prescribed for a defined period-either short-term for a cancer-related protocol or long-term for chronic blood disorders-depending on the individual's condition. Always follow the instructions that come with the specific medicine and keep the prescribing clinician informed of any new symptoms or concerns.

For detailed usage, dosing, administration, and monitoring, refer to the information provided with your particular medication.

Information Disclaimer

This article offers general educational information about hydroxyurea as an active substance used in various medicines. Its purpose is to help patients better understand the ingredient and the conditions it is used to treat. It is not a substitute for professional medical advice or for the specific instructions provided with individual products. Medicines containing hydroxyurea may differ in formulation, strength, and directions for use. Always consult the labeling of your particular medication and follow your healthcare provider’s guidance for complete information on proper use, dosage, and safety.