Hydralazine

Essential hypertension, alone or as an adjunct.

Prescribing label

Selected manufacturer label information, organised into consistent sections by Sofidex. This source is written for healthcare professionals; ask your pharmacist to explain instructions that are unclear. Read the full label at DailyMed ↗

Drug facts

Used for: Essential hypertension, alone or as an adjunct.
How to take it: Initiate therapy in gradually increasing dosages; adjust according to individual response.
Do not take if: Hypersensitivity to hydrALAZINE; coronary artery disease; mitral valvular rheumatic heart disease.

How to take it

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. In a few resistant patients, up to 300 mg of hydrALAZINE daily may be required for a significant antihypertensive effect. In such cases, a lower dosage of hydrALAZINE 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.

Side effects, and when to stop

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. o Cardiovascular: hypotension, paradoxical pressor response, edema. o Respiratory: dyspnea o Neurologic: peripheral neuritis, evidenced by paresthesia, numbness, and tingling; dizziness; tremors; muscle cramps; psychotic reactions characterized by depression, disorientation, or anxiety. o Genitourinary: difficulty in urination o Hematologic: blood dyscrasias, consisting of reduction in hemoglobin and red cell count, leukopenia, agranulocytosis, purpura; lymphadenopathy; splenomegaly. o Hypersensitivity Reactions: rash, urticaria, pruritus, fever, chills, arthralgia, eosinophilia, and rarely, hepatitis. o Other: nasal congestion, flushing, lacrimation, conjunctivitis.

Who should not take it

Hypersensitivity to hydrALAZINE; coronary artery disease; mitral valvular rheumatic heart disease.

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.)

General

Myocardial stimulation produced by hydrALAZINE can cause anginal attacks and ECG changes of myocardial ischemia. The drug has been implicated in the production of myocardial infarction. It must, therefore, be used with caution in patients with suspected coronary artery disease. The “hyperdynamic” circulation caused by hydrALAZINE may accentuate specific cardiovascular inadequacies. For example, hydrALAZINE may increase pulmonary artery pressure in patients with mitral valvular disease. The drug may reduce the pressor responses to epinephrine. Postural hypotension may result from hydrALAZINE but is less common than with ganglionic blocking agents. It should be used with caution in patients with cerebral vascular accidents. In hypertensive patients with normal kidneys who are treated with hydrALAZINE, there is evidence of increased renal blood flow and a maintenance of glomerular filtration rate. In some instances where control values were below normal, improved renal function has been noted after administration of hydrALAZINE. However, as with any antihypertensive agent, hydrALAZINE should be used with caution in patients with advanced renal damage. Peripheral neuritis, evidenced by paresthesia, numbness, and tingling, has been observed. Published evidence suggests an antipyridoxine effect, and that pyridoxine should be added to the regimen if symptoms develop.

Cite this page

NLM: sofidex [Internet]. Daloreum; c2026. Hydralazine; [reviewed 2026 Aug 2; cited 2026 Nov 10]. Available from: https://sofidex.com/patients/medicines/hydralazine
APA 7th: sofidex. (2026, August 2). Hydralazine. Daloreum. Retrieved November 10, 2026, from https://sofidex.com/patients/medicines/hydralazine
AMA 11th: Hydralazine. sofidex. Reviewed August 2, 2026. Accessed November 10, 2026. https://sofidex.com/patients/medicines/hydralazine

The cited date is today’s, because a citation records when you read the page. The reviewed date is when a clinician last checked it.