Hydralazine (Injection)


Hydralazine is a medicine that is given to patients suffering from hypertension (high blood pressure). It is important that you treat high blood pressure as it puts added workload on to your arteries and heart. If this goes on for a long time, these arteries and your heart may not function properly. In turn, this can damage the blood vessels in your kidneys, heart, and brain which can result in kidney failure, heart failure, or a stroke. By lowering your blood pressure, you can relieve the risks of this occurring.

Hydralazine works by relaxing your blood vessels, which in turn increases the supply of oxygen and blood to your heart. This reduces the workload placed on your heart. You can only obtain Hydralazine following a prescription, as it is only suitable for certain patients.

Condition(s) treated

  • Hypertension (high blood pressure)

Type of medicine

  • Solution for injection

Side effects

As well as helping to treat high blood pressure, it is possible that Hydralazine will cause you to experience other unwanted side effects. These side effects can range in severity, but directly below is a list of the more severe ones. If you experience any of these effects listed here, then you should contact your doctor immediately.

More common

  • Chest discomfort or pain

Less common

  • A cough


  • Vomiting and nausea

Below are the symptoms of overdose. If you experience any of these, then seek emergency medical attention.

As mentioned, the side effects you experience will not necessarily be very severe. Directly below is a list of the less serious side effects associated with this drug. You may find that the effects will pass as your treatment for hypertension continues and your body adjusts to the medicine. However, if the side effects are bothersome or lingering, you may still contact your doctor. They may be able to alter your doses or advise on other methods to reduce the unwanted effects.

More common

  • Loss of appetite

Less common

Though these lists are extensive, they are not necessarily complete. This means you may experience some other side effects that are not listed here. If that's the case, and you would like to discuss your side effects, then you can still contact your doctor.


You will not need to worry about dosages of this medicine. A trained doctor, nurse, or other health professional will administer it in a clinical setting. It is injected via a needle that is placed in one of your veins.

Your doctor will likely give you a few doses of Hydralazine until your condition starts to improve. Afterwards, they will likely then switch you to an oral form of medicine that works in the same way. If you would like to discuss your dosages, or have any concerns, address them to your doctor.


It is possible that Hydralazine will interact with other drugs you are currently taking. In some cases, these interactions are severe and must be avoided. However, in other cases, they may be less severe and necessary. Under such circumstances, your doctor may decide to alter the dose you receive of one or both medicines to limit the interaction. You should advise your doctor of all drugs you are currently taking. Directly below is a list of drugs which are known to react more severely with Hydralazine.

  • Tizanidine

Here is a list of some of the drugs which are known to interact moderately with Hydralazine.

  • Quetiapine

Here is a list of drugs which are known to have a minor interaction with Hydralazine.

  • Metoprolol / hydrochlorothiazide

As well as interacting with drugs, it is possible that Hydralazine will interact with certain aspects of your dietary intake. Yoru doctor there may advise you make adjustments to what you eat, drink, or smoke. If so, you should follow these changes as best as possible.

Lastly, it is possible that Hydralazine will interact with other medical problems that you suffer from, or have suffered from in the past. Inform your doctor of your complete medical history, and highlight any of the following.

  • A history of heart attacks


Before prescribing you with this medicine, your doctor will give you a full medical examination to decide whether it is the most suitable course of treatment. As a part of this examination, you will need to make them aware of any allergies you have. This includes any allergies to foods, preservatives, animals, and dyes.

As of writing, there have been no suitable studies performed on the effects this drug has on pediatric patients. However, no pediatric-specific problems have yet been documented.

There is no current information regarding the geriatric-specific problems that Hydralazine may have.

As of writing, it is unclear as to whether this is a safe drug for pregnant women to receive. Your doctor is best placed to advise you of any increased risks, and to then weigh them against the benefits the medicine holds.

Studies performed on breastfeeding women taking this drug show that there are minimal risks to the infant.

Whilst receiving this medicine, your doctor will schedule you in for regular appointments. It is important that you attend all of these as it is a chance for your doctor to check for unwanted effects and make any necessary adjustments to your prescription. You may be required to have blood tests at these appointments.

Some people receiving this medicine will experience dizziness or have headaches. You should therefore not drive or perform any other dangerous tasks until you know exactly how Hydralazine affects you.

Unless first cleared by your doctor, do not take any other medicines at the same time as Hydralazine. This includes any prescription and nonprescription drugs, as well as any herbal or vitamin supplements. In particular do not take any medicines for hay fever, coughs, asthma, colds, appetite control, or sinus problems. These medicines can potentially increase your blood pressure.


You will not be required to store Hydralazine.


If you suffer from hypertension, then it is important that you seek appropriate treatment. By failing to do so you put yourself at risk of a number of life-threatening health complications. Hydralazine is a drug that can potentially help lower your blood pressure and improve your quality of life. However, you should be aware that it is strictly made available to only certain patients, due to the interactions it can cause.

If you are prescribed it, you should be careful in following any other lifestyle changes your doctor gives you. This will greatly improve the effectiveness it has in treating your condition. If you have any questions regarding this medicine, such as side effects it has, then you should address these to your doctor.