Hydralazine
Also sold as: Bidil
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These drugs share a pharmacologic classification but are NOT interchangeable. Listing here does not imply clinical equivalence. A physician must evaluate each drug individually for the patient's specific condition.
Classification: Arteriolar Vasodilation (source: RxClass/NLM)
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Insurance Coverage User-Reported
No community coverage data yet for hydralazine.
Coverage data submission coming soon.
Drug Information
Indications & Uses
INDICATIONS AND USAGE Essential hypertension, alone or as an adjunct.
Dosage & Administration
DOSAGE AND ADMINISTRATION Initiate therapy in gradually increasing dosages; adjust according to individual response. Start with 10 mg four times daily for the first 2 to 4 days, increase to 25 mg four times daily for the balance of the first week. For the second and subsequent weeks, increase dosage to 50 mg four times daily. For maintenance, adjust dosage to the lowest effective levels. The incidence of toxic reactions, particularly the L.E. cell syndrome, is high in the group of patients receiving large doses of hydrALAZINE hydrochloride tablets. In a few resistant patients, up to 300 mg of hydrALAZINE hydrochloride tablets daily may be required for a significant antihypertensive effect. In such cases, a lower dosage of hydrALAZINE hydrochloride tablets combined with a thiazide and/or reserpine or a beta blocker may be considered. However, when combining therapy, individual titration is essential to ensure the lowest possible therapeutic dose of each drug.
Warnings & Precautions
WARNINGS In a few patients hydrALAZINE may produce a clinical picture simulating systemic lupus erythematosus including glomerulonephritis. In such patients hydrALAZINE should be discontinued unless the benefit-to-risk determination requires continued antihypertensive therapy with this drug. Symptoms and signs usually regress when the drug is discontinued but residua have been detected many years later. Long-term treatment with steroids may be necessary. (See PRECAUTIONS, Laboratory Tests .)
Side Effects (Adverse Reactions)
ADVERSE REACTIONS Adverse reactions with hydrALAZINE are usually reversible when dosage is reduced. However, in some cases it may be necessary to discontinue the drug. The following adverse reactions have been observed, but there has not been enough systematic collection of data to support an estimate of their frequency. Common Headache, anorexia, nausea, vomiting, diarrhea, palpitations, tachycardia, angina pectoris. Less Frequent: Digestive: constipation, paralytic ileus. Cardiovascular: hypotension, paradoxical pressor response, edema. Respiratory: dyspnea. Neurologic: peripheral neuritis, evidenced by paresthesia, numbness, and tingling; dizziness; tremors; muscle cramps; psychotic reactions characterized by depression, disorientation, or anxiety. Genitourinary: difficulty in urination. Hematologic: blood dyscrasias, consisting of reduction in hemoglobin and red cell count, leukopenia, agranulocytosis, purpura; lymphadenopathy; splenomegaly. Hypersensitive Reactions: rash, urticaria, pruritus, fever, chills, arthralgia, eosinophilia, and rarely, hepatitis. Other: nasal congestion, flushing, lacrimation, conjunctivitis.
Contraindications
CONTRAINDICATIONS Hypersensitivity to hydrALAZINE; coronary artery disease; mitral valvular rheumatic heart disease.
Verify with Primary Sources
Always verify clinical information with authoritative sources.
Medical Disclaimer: Information on this page is sourced from FDA-approved labeling data and is for educational reference only. It does not constitute medical advice. This information does not establish a provider-patient relationship. Always verify with current prescribing information and consult a licensed healthcare professional before any clinical decision. Read full disclaimer.
Data sourced from RxNorm (NLM/NIH), FDA Orange Book, OpenFDA, DailyMed. Last updated: 2026-03-02.