Hydralazine: Uses, Side Effects, and How to Take It
Hydralazine is a prescription blood pressure medicine that relaxes and widens blood vessels. It is used to treat high blood pressure and sometimes heart failure, usually along with other medicines.
Hydralazine can help lower blood pressure, but it may cause dizziness, rapid heartbeat, fluid retention, or a lupus-like immune reaction. Take it exactly as prescribed and ask your doctor or pharmacist about risks and interactions.
Key facts at a glance
- ATC
- C02DB02
- Generic
- Hydralazine
- Class
- vasodilator
- Brands
- Apresoline
- Availability
- rx
- Pregnancy
- C
- Lactation
- caution
- Half-life (h)
- 4
- Onset (min)
- 30
- Duration (h)
- 8
- Routes
- oral, iv
- Forms
- tablet, injection
- Regions
- CN, US, EU, JP
- Monitoring
- blood-pressure, heart-rate
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 25mg four times daily
- Maximum
- consult physician
- Frequency
- every 6 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 0.75mg/kg four times daily
- Maximum
- consult physician
- Frequency
- every 6 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 10mg three times daily
- Maximum
- consult physician
- Frequency
- every 8 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
6 groupspregnancy
generaluse lowest effective dose
may be used for severe hypertension/preeclampsia when benefits outweigh risks
regular blood pressure monitoring and fetal monitoring
Use with caution and monitor for adverse effects.
lactation
generalno specific adjustment
compatible with breastfeeding per AAP; monitor infant for hypotension
monitor infant for lethargy, poor feeding
Use with caution and monitor for adverse effects.
geriatric
age 65 and olderstart at 10-25mg daily (lower end of adult range)
increased sensitivity to hypotensive effects; start low and titrate slowly
frequent blood pressure monitoring, watch for orthostatic hypotension
Use with caution and monitor for adverse effects.
pediatric_age
children adolescents0.5-2 mg/kg/day divided 2-4 times daily, max 25 mg/day initially
used for hypertension in children; limited long-term safety data
monitor blood pressure, heart rate, lupus-like symptoms with long-term use
Use with caution and monitor for adverse effects.
renal_impairment
severereduce dose; monitor closely
primarily renally excreted; adjust dose in severe impairment (CrCl <30 mL/min)
frequent renal function monitoring, blood pressure monitoring
Use with caution and monitor for adverse effects.
hepatic_impairment
moderate to severereduce dose or avoid in severe impairment
extensively metabolized in liver; use with caution in hepatic impairment
monitor blood pressure, liver function tests
Use with caution and monitor for adverse effects.
Statistics and clinical data
Drug class
Hydralazine belongs to the ATC class C02DB01 (Hydrazinophthalazine derivatives)
Primary indications
Therapeutic uses of Hydralazine
Mechanism of action
Pharmacological mechanism
FDA approval year
Original FDA approval date for Apresoline
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 22, 2026. · Read our editorial policy