If you have a certain kind of blood or skin cancer, your doctor might suggest Hydrea as a treatment option for you. It’s a prescription drug used to treat the following conditions in adults:

The active ingredient in Hydrea is hydroxyurea. An active ingredient is what makes a drug work.

Hydrea comes as a capsule you swallow. It belongs to a group of cancer drugs called antimetabolites.

This article describes the dosages of Hydrea, as well as its strength and how to take it. To learn more about Hydrea, see this in-depth article.

The chart below highlights the basics of Hydrea’s dosage. Be sure to read on for more detail.

Hydrea formHydrea strengthHydrea usual dosage
capsule 500 milligrams (mg)dosage is individualized based on weight and certain other factors

Note: Please keep in mind that this article covers information about Hydrea, which is provided by the drug’s manufacturer. But always follow the dosing instructions your doctor prescribes.

Information on how Hydrea dosage is determined for its approved uses is described below.

What is Hydrea’s form?

Hydrea comes as a capsule you swallow whole.

What strength does Hydrea come in?

Hydrea comes in 500-milligram (mg) capsules.

What are the usual dosages of Hydrea?

The information below describes how your doctor will determine the best dosage of Hydrea to fit your needs.

Dosage for chronic myeloid leukemia

The manufacturer has not given a specific Hydrea dosage recommendation for chronic myeloid leukemia. The dosage is individualized based on certain factors. These include:

  • your body weight
  • the severity of your condition
  • if you have kidney problems
  • if you’re age 65 years or older

Dosage for head and neck skin cancer

Hydrea is prescribed together with chemotherapy (traditional drugs used to treat cancer) and radiation therapy when treating squamous cell cancer of the head and neck. A specific dosage hasn’t been given by the manufacturer for this purpose. The dosage is individualized, based on factors such as:

  • your body weight
  • the severity of your condition
  • your kidney function
  • if you’re age 65 years or older

Is Hydrea prescribed long term?

Yes, Hydrea is usually prescribed as a long-term treatment. If you and your doctor determine that Hydrea is safe and effective for you, you’ll likely take it long term.

Dosage adjustments

Older adults may be more sensitive to Hydrea. Your doctor may start you taking a lower dose if you’re age 65 years or older.

Also, if you have kidney problems, your dosage of Hydrea will likely be lower. Your doctor will adjust your dosage to one that’s right for you.

Below are answers to some common questions about Hydrea dosing.

Can I take 1,000 mg of Hydrea for my cancer? What is the maximum dose I can take?

Your doctor may determine that a Hydrea dosage of 1,000 milligrams (mg) is right for you. Your dosage of Hydrea is based on your body weight. Other factors also affect your dosage, such as if you’re age 65 years or older or have kidney problems.

The manufacturer doesn’t provide a recommendation for a maximum dose of Hydrea. Your doctor will consider your condition and other factors to determine the right dose for you.

I have kidney problems. Will this affect my dosage of Hydrea?

Yes, if you have kidney problems, your doctor will likely start you taking a lower dose of Hydrea. Renal dosing is when a drug’s dosage is adjusted for kidney disease. (“Renal” means relating to the kidneys.)

If you have kidney disease, your kidneys may not be able to remove a drug from your body quickly enough. This can lead to having too much of the drug in your body, which can increase your risk of side effects. Your doctor will perform some tests to determine how well your kidneys are working. They will then prescribe the dosage that’s right for you.

Depending on the severity of your kidney disease, your doctor may reduce your Hydrea dose by 50%.

If you develop kidney problems while taking Hydrea, your doctor will likely lower your dose.

The dosage of Hydrea you’re prescribed may depend on several factors. These include:

  • the kind and severity of the condition you’re taking Hydrea to treat
  • your age
  • your weight
  • how your body responds to treatment
  • other conditions you may have (see “Dosage adjustments” under “What is Hydrea’s dosage?”)

Hydrea capsules should be swallowed whole. Do not chew or break open the capsules. Hydrea is cytotoxic (harmful to living cells), so it can be dangerous if you open the capsule.

Wash your hands with soap and water before and after handling Hydrea or the container. Caregivers should wear disposable gloves when handling Hydrea capsules or containers.

Your doctor may advise you to take folic acid during treatment with Hydrea. This is because Hydrea can cause macrocytosis (making your red blood cells larger than usual). Taking folic acid with Hydrea helps prevent this side effect.

For information on Hydrea expiration, storage, and disposal, see this article.

Accessible drug containers and labels

If you find it hard to read the prescription label on your medication, tell your doctor or pharmacist. Some pharmacies provide medication labels that:

  • have large print or use braille
  • feature a code that you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend pharmacies that offer these accessibility features if your current pharmacy doesn’t.

If you have trouble opening medication bottles, let your pharmacist know. Hydrea comes in a bottle made of a certain protective plastic with a safety screw cap. Your pharmacist may also have some tips that can help make it easier to open the drug’s container safely.

Talk with your doctor or pharmacist If you miss a dose of Hydrea. They can recommend if you should take or skip the missed dose.

If you need help remembering to take your dose of Hydrea on time, try using a medication reminder. This can include setting an alarm or downloading a reminder app on your phone.

Do not take more Hydrea than your doctor prescribes. Doing so can lead to serious side effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

What to do in case you take too much Hydrea

Call your doctor right away if you think you’ve taken too much Hydrea. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use its online resource. But if you have severe symptoms, call 911 (or your local emergency number) immediately or go to the nearest emergency room.

The sections above describe the recommendations provided by the drug’s manufacturer. If your doctor recommends Hydrea for you, they’ll prescribe the dosage that’s right for you.

Remember, you should not change your dosage of Hydrea without your doctor’s recommendation. Only take Hydrea exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage.

Here are some examples of questions you may want to ask your doctor:

  • Will you adjust my dosage of Hydrea if I take other medications with it?
  • If I have problems with my liver, will you lower my dosage of Hydrea?
  • Can Hydrea be prescribed for polycythemia vera or sickle cell disease? If so, is the dosage different?


What is drug toxicity? Will my dose of Hydrea change if I experience it during treatment?



Drug toxicity occurs when the amount of a drug in your system is too high and causes adverse effects. It can occur when the dose is too high or if your liver or kidneys aren’t able to remove the drug from your system as they should.

Before starting Hydrea, talk with your doctor about your overall health and your risk of drug toxicity. Hydrea has certain precautions that should be considered. If you have certain conditions or have been treated with certain other drugs, your risk of toxicity may be higher.

While taking Hydrea, your blood counts will likely be monitored every week to make sure you don’t develop drug toxicity. If you do develop toxicity that causes certain blood cell or blood vessel problems, your doctor may lower your Hydrea dosage or have you stop taking it altogether.

For more information about Hydrea precautions and toxicity, talk with your doctor.

The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.