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Hydrea Side Effects

Generic Name: hydroxyurea

Note: This page contains information about the side effects of hydroxyurea. Some of the dosage forms included on this document may not apply to the brand name Hydrea.

Not all side effects for Hydrea may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to hydroxyurea: oral capsule, oral tablet

In addition to its needed effects, some unwanted effects may be caused by hydroxyurea (the active ingredient contained in Hydrea). In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking hydroxyurea:

More common
  • Cough or hoarseness
  • fever or chills
  • lower back or side pain
  • painful or difficult urination
Less common
  • Black, tarry stools
  • blackening of the fingernails and toenails
  • blood in the urine or stools
  • pinpoint red spots on the skin
  • sores in the mouth and on the lips
  • unusual bleeding or bruising
  • Confusion
  • convulsions (seizures)
  • difficulty with urination
  • dizziness
  • headache
  • joint pain
  • seeing, hearing, or feeling things that are not there
  • swelling of the feet or lower legs
Incidence not known
  • Bleeding under the skin
  • blisters on the skin
  • bluish or pale color on the skin of the fingers or toes
  • coldness of the fingers or toes
  • crater-like lesions on the skin
  • itching skin
  • numbness or tingling of the fingers or toes
  • pain in the fingers or toes
  • unusual tiredness or weakness
  • weight loss

If any of the following symptoms of overdose occur while taking hydroxyurea, get emergency help immediately:

Symptoms of overdose
  • Scaling of the skin on the hands and feet
  • severe darkening of skin color
  • soreness
  • sores in the mouth and on the lips
  • swelling of the palms and soles of the feet
  • violet flushing of the skin

Some of the side effects that can occur with hydroxyurea may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Diarrhea
  • drowsiness
  • loss of appetite
  • nausea or vomiting
Less common
  • Constipation
  • redness of skin at the place of irradiation
  • skin rash and itching

For Healthcare Professionals

Applies to hydroxyurea: compounding powder, oral capsule, oral tablet


Very common (10% or more): Bone marrow failure, CD4 lymphocytes decreased, leukopenia, thrombocytopenia, platelet count decreased, anemia
Common (1% to 10%): Neutropenia[Ref]


Very common (10% or more): Pancreatitis, nausea, vomiting, diarrhea, stomatitis, constipation, mucositis, stomach discomfort, dyspepsia, abdominal pain, melena[Ref]


Very common (10% or more): Pyrexia, asthenia, chills, malaise, fever, edema[Ref]


Very common (10% or more): Cutaneous vasculitis, dermatomyositis, alopecia, maculopapular rash, papular rash, skin exfoliation, skin atrophy, skin ulcer, erythema, skin hyperpigmentation, nail disorder
Very rare (less than 0.01%): Transverse melanonychia
Frequency not reported: Squamous dysplasia, facial erythema[Ref]


Common (1% to 10%): Skin cancers, neoplasms benign and malignant [including cysts and polyps])
Frequency not reported: This drug has been shown to be mutagenic, clastogenic, and cause cellular transformation to a tumorigenic phenotype. This drug has been reported to be unequivocally genotoxic and a presumed transspecies carcinogen, which implies a carcinogenic risk to humans.[Ref]


Very common (10% or more): Azoospermia, oligospermia
Very rare (less than 0.01%): Dysuria[Ref]

Nervous system

Common (1% to 10%): Convulsion, dizziness, peripheral neuropathy, drowsiness
Frequency not reported: Severe peripheral neuropathy has been reported in HIV-infected patients who received this drug in combination with antiretroviral drugs[Ref]


Common (1% to 10%): Hepatotoxicity, hepatic enzyme increased, cholestasis, hepatitis
Frequency not reported: Both fatal and nonfatal hepatotoxicity have been reported in HIV-infected patients who received this drug in combination with antiretroviral agents[Ref]


Common (1% to 10%): Pulmonary fibrosis, pulmonary edema, lung infiltration, dyspnea[Ref]


Very rare (less than 0.01%): Tumor lysis syndrome[Ref]


Common (1% to 10%): Hallucination, disorientation[Ref]


Very common (10% or more): Dysuria, blood creatinine increased, blood urea increased, blood uric acid increased[Ref]


1. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. Available from: URL:" ([2006]):

2. "Product Information. Droxia (hydroxyurea)." Bristol-Myers Squibb, Princeton, NJ.

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.