> Western Medicines > Hydralazine


Chinese name:

What is Hydralazine for?

Hydralazine is a vasodilator that can relax the blood vessels in your heart and hence increase the blood and oxygen supply to your heart. It can be used to treat high blood pressure and chronic heart failure.

How to use it?

Hydralazine can be taken by mouth as tablets.


If you are using it for high blood pressure, the usual starting dose is 10 mg four times daily.


If you are using it for chronic heart failure, you should take Hydralazine with a long-acting nitrate and start with 25 mg 3-4 times daily.


Hydralazine doses are gradually increased based on your responses. The usual maintenance dose is 50-75 mg 4 times daily.

What are the side effects of Hydralazine?

Common side effects of Hydralazine include angina, swelling in arms and legs (oedema), diarrhoea, dizziness, flushing, gastrointestinal disorders, headache, low blood pressure, joint disorders, muscle pain, nasal congestion, nausea and vomiting, palpitations, and fast heart beats.

Who should not take Hydralazine?

  • People who are allergic to Hydralazine or any formulation component
  • Patients with coronary artery disease, mitral valve rheumatic heart disease or acute porphyrias (a blood disorder)

Pharmacist Tips:

  • Continue taking Hydralazine even when you feel well.
  • Stop taking Hydralazine and report to your healthcare provider if you get drug-induced lupus. Symptoms include rash, muscle and joint pain, and feeling very tired.

Common dosing schedule:
You can take Hydralazine with or without food, but keep it consistent as this may affect the amount of drug absorbed.


This schedule is for reference only, adjustments may be made according to individual needs.


Some common medications Hydralazine may interact with:

  • Other medicines for treating hypertension, such as calcium channel blockers (e.g. Amlodipine), beta blockers (e.g. Atenolol), angiotensin-converting enzyme inhibitors (e.g. Ramipril
  • Levodopa

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Hydralazine in Hong Kong?

In Hong Kong, Hydralazine is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.


For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Hydralazine in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.

Brands in Hong Kong
Available dosage
  • 10mg / 25mg / 50mg (Tablets)
Drug class
Antihypertensives, Vasodilators
Sub class
Peripheral Vasodilators
Other drugs in same class