Sounds like 'hy-droxy-you-rea'

Hydroxyurea is used to treat conditions such as some types of cancers and sickle-cell disease. Find out how to take it safely and the possible side effects. Hydroxyurea is also called hydroxycarbamide or Hydrea.

What is hydroxyurea?

Hydroxyurea is used to treat several conditions including some types of cancer and sickle cell disease. It works by slowing the growth of some cells.

For sickle cell disease, hydroxyurea stops red blood cells from changing to a sickle shape. It can help with symptoms of pain and reduce the number and severity of crises, episodes of acute chest pain and blood transfusions. It can also prevent or slow down damage to your organs. 


  • In Aotearoa New Zealand, hydroxyurea is available as 500 mg capsules.
  • The dose is based on your body weight and the condition. 
  • The dose of hydroxyurea is different for different people.
  • Your doctor will calculate your dose based on your condition, your blood test results and your response.
  • For some conditions like sickle cell disease, your doctor will start you on a low dose and will increase it after a few months depending on how you tolerate it.
  • Always take your hydroxyurea exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much hydroxyurea to take, how often to take it and any special instructions.

How to take hydroxyurea

  • Timing
    • Take hydroxyurea with food. Swallow the capsule whole with a glass of water. 
    • Most people take hydroxyurea pills once a day. Your doctor will prescribe the dose he or she thinks is right for you. Sometimes you may need to take a different number of pills on certain days.
  • Difficulty swallowing: If you are unable to swallow the capsules whole, you can empty the capsule contents into a glass of water. stir well, and drink it straight away. Wear gloves when handling the capsules and wash your hands before and after.
  • Folic acid: Your doctor may also prescribe a vitamin tablet called folic acid. Taking this vitamin can help reduce the severity of some side-effects associated with hydroxyurea.
  • Missed dose: If you forget to take your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Precautions before starting hydroxyurea

  • Are you breastfeeding, pregnant or planning on having a baby?
  • Do you have any problems with your kidneys or liver?
  • Do you have leg ulcers?
  • Do you have gout?
  • Are you taking any other medicines, any over-the-counter and complementary medicines, eg, vitamins, minerals, herbal or naturopathic medicines?

If you have answered yes to any of these questions, it’s important that you tell your doctor or pharmacist before you take hydroxyurea. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Precautions while taking hydroxyurea

Blood tests

You will need regular blood tests while taking hydroxyurea to check if it is causing problems with your liver, kidneys or blood.


Hydroxyurea can cause harm to an unborn baby. It is important that you do not get pregnant while you are taking hydroxyurea. Talk to your doctor about contraception.

Protect your skin

Rarely, people who take hydroxyurea over a long period of time can develop skin cancer. Reduce your risk by protecting your skin from the sun –even on a bright but cloudy day.


Some vaccines cannot be taken while on hydroxyurea treatment and for 6 months after stopping. Talk to your doctor about your options.

What are the side effects of hydroxyurea?

Like all medicines, hydroxyurea can cause side effects, but not everyone gets them. Often side effects improve as your body gets used to the new medicine. 

Side effects What should I do?
  • Sore throat or mouth
  • High temperature (fever) 
  • Chills
  • Increased tiredness
  • As hydroxyurea can lower your white blood cells you are more likely to get an infection.
  • Tell your doctor immediately or ring Healthline 0800 611 116.
  • Unusual bruising or bleeding
  • As hydroxyurea can lower your platelet numbers you are more likely to bleed.
  • Avoid tasks where you may bruise or get injured.
  • Tell your doctor immediately or ring Healthline 0800 611 116.
  • Feeling sick (nausea)
  • Loss of appetite
  • Runny poos (diarrhoea)
  • Constipation
  • Tummy pain
  • Indigestion
  • Change in nails
  • Thinning of hair
  • These are quite common.
  • Tell your doctor if they bother you.
  • Feeling sleepy
  • Do not drive or use tools or machines.
  • Gout
  • Contact your doctor.
For more information on side effects, see the consumer information leaflet here.

Did you know that you can report a medicine side effect to the Centre for Adverse Reactions Monitoring (CARM)? Report a side effect to a product

Learn more

The following links have more information on hydroxyurea. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Hydoxycarbamide Consumer Information, NZ
 PatientInfo, UK
Using Hydroxycarbamide (Hydroxyurea) for adult patients with sickle cell disease St George's Hospitals NHS, UK
Hydroxycarbamide for cancer Macmillan, UK
Hydroxyurea DermNet, NZ
Hydroxycarbamide for psoriasis British Association of Dermatologists, UK


Hydroxycarbamide (hydroxyurea) NZ Formulary
Hydroxycarbamide (Devatis) Medsafe, NZ

Credits: Maya Patel, MPharm PGDipClinPharm, Auckland.