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Siklos Side Effects

Generic name: hydroxyurea

Medically reviewed by Drugs.com. Last updated on Jul 20, 2022.

Note: This document contains side effect information about hydroxyurea. Some dosage forms listed on this page may not apply to the brand name Siklos.

Applies to hydroxyurea: oral capsules.

Warning

    Toxicity
  • Highly toxic drug with a low therapeutic index.c

  • Possible severe, sometimes life-threatening or fatal, adverse effects.177 178

    Limit to Qualified Personnel
  • Administer only under supervision of qualified clinicians experienced in use of cytotoxic therapy.177 178 (See Adequate Patient Evaluation and Monitoring under Cautions.)

    Carcinogenicity
  • Hydroxyurea is genotoxic and is a presumed human carcinogen;177 178 also, mutagenic and clastogenic in vitro.177 178

  • Secondary leukemias have been reported in patients receiving long-term therapy for myeloproliferative disorders (e.g., polycythemia vera, thrombocythemia).177 178

  • Carefully consider risks of developing secondary malignancies against the benefits of therapy.a (See Carcinogenicity under Cautions.)

Side effects include:

Bone marrow suppression.

For Healthcare Professionals

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

General

The more commonly reported adverse reactions among children have been infections and neutropenia. Among adults, hematologic, gastrointestinal symptoms, infections, headache, anorexia, and dry skin have been commonly reported.

Hematologic

Very common (10% or more): Neutropenia (13%)

Common (1% to 10%): Thrombocytopenia, anemia

Postmarketing reports: Hemolytic anemia, macrocytosis[Ref]

Gastrointestinal

Common (1% to 10%): Nausea, upper abdominal pain, diarrhea, constipation

Postmarketing reports: Stomatitis, vomiting, gastrointestinal ulcer, oral mucositis, pancreatitis[Ref]

Pancreatitis has occurred when hydroxyurea was administered concomitantly with antiretroviral drugs, including didanosine and stavudine.[Ref]

Other

Common (1% to 10%): Fever, asthenia, pyrexia, fatigue, peripheral edema

Postmarketing reports: Chills, malaise[Ref]

Dermatologic

Very common (10% or more): Dry skin (12%)

Common (1% to 10%): Skin ulcer, alopecia

Postmarketing reports: Skin ulceration, cutaneous lupus erythematosus, dermatomyositis-like skin changes, peripheral and facial erythema, nail hyperpigmentation, atrophy of skin and nails, scaling, violet papules, skin reactions (oral, ungula and cutaneous pigmentation), rash, melanonychia[Ref]

Oncologic

Leukemia secondary to long-term hydroxyurea (the active ingredient contained in Siklos) has also been reported in patients with sickle cell disease. Leukemia has also been reported in patients with sickle cell disease and no prior history of treatment with hydroxyurea. Skin cancer has also been reported in patients receiving long-term hydroxyurea.[Ref]

Frequency not reported: Leukemia, skin cancers[Ref]

Genitourinary

Common (1% to 10%): Urinary tract infection

Postmarketing reports: Azoospermia, oligospermia, amenorrhea, dysuria[Ref]

Nervous system

Peripheral neuropathy has occurred when hydroxyurea (the active ingredient contained in Siklos) was administered concomitantly with antiretroviral drugs, including didanosine and stavudine.[Ref]

Very common (10% or more): Headache (20%)

Common (1% to 10%): Dizziness

Frequency not reported: Peripheral neuropathy

Postmarketing reports: Drowsiness, convulsions[Ref]

Hepatic

Uncommon (0.1% to 1%): 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]

Respiratory

Common (1% to 10%): Cough, lung disorder, dyspnea, nasopharyngitis

Postmarketing reports: Diffuse pulmonary infiltrates, dyspnea, pulmonary fibrosis, interstitial lung disease, pneumonitis, alveolitis, allergic alveolitis[Ref]

Metabolic

Common (1% to 10%): Vitamin D deficiency, other metabolic and nutrition disorders, weight gain, increased weight

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

Postmarketing reports: Anorexia, severe hypomagnesemia[Ref]

Psychiatric

Postmarketing reports: Hallucinations, disorientation[Ref]

Renal

Postmarketing reports: Elevations in serum uric acid, blood urea nitrogen (BUN), and creatinine levels[Ref]

Hypersensitivity

Drug-induced fever requiring hospitalization has been reported in the postmarketing period. It has been reported concurrently with gastrointestinal, pulmonary, musculoskeletal, hepatobiliary, dermatological or cardiovascular manifestations. Onset typically occurred within 6 weeks of initiation and resolved upon discontinuation of hydroxyurea (the active ingredient contained in Siklos) Upon re-administration fever reoccurred typically within 24 hours.

Postmarketing reports: Drug-induced fever

Immunologic

Common (1% to 10%): Viral infections, bacterial infections, influenza

Postmarketing reports: Systemic lupus erythematosus

Musculoskeletal

Common (1% to 10%): Arthralgia, back pain, extremity pain

References

1. "Product Information. Droxia (hydroxyurea)." Bristol-Myers Squibb (2001):

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

3. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. http://www.appco.com.au/appguide/default.asp" (2006):

4. "Product Information. Hydroxyurea (hydroxyurea)." Par Pharmaceutical Inc (2022):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.