Hydralazine and Hydrochlorothiazide (Oral)


High blood pressure can be a dangerous condition. It forces your heart and the arteries in your body to work harder than they were designed to. As time goes by, the extra work these parts take on will damage your heart and the arteries and blood vessels in your body, as well as other parts of your body, if it cannot be brought under control by medication and lifestyle changes.

Hydralazine and hydrochlorothiazide is a vasodilator and thiazide combination drug that relaxes blood vessels, increases the supply of blood and oxygen to the heart and reduces the body's workload at the same time. It also works as a diuretic by acting on the kidneys to increase the flow of urine and reduce the amount of water in the body.

While this medication does help to lower your blood pressure, it is not a cure for hypertension. It is used as part of an overall treatment plan for the condition. Besides medication, the typical treatment plan for high blood pressure includes dietary changes and regular exercise to help manage it.

This medication is only available with a prescription from your doctor. It is available under the brand name Apresazide.

Conditions Treated

Types of medication

  • Vasodilator/thiazide combination

Side Effects

Hydralazine and hydroclorothiazide, like many other medications, was created so that it could help to improve the health of the person taking it. Because no one individual's medical condition is exactly the same as another's, there will be times when unintended side effects (otherwise known as adverse reactions) occur. Some of these effects are less serious than others and may not need medical attention. If you have any questions or concerns about the possible effects of this medication, you should talk to your doctor.

Some adverse reactions to hydralazine and hydrochlorothiazide include:

Should any of the above side effects continue after this medicine has taken full effect or worsen as you continue to take it, talk to your doctor about ways to mitigate the negative effects, potentially by adjusting your dosage, if necessary.

Other side effects occur less often while taking this medication. If they are happening, you should consult a healthcare professional. They include:

One potentially dangerous side effect of using this medication is the loss of too much potassium. A patient might be having this issue if they are experiencing:

  • Dry mouth

Another serious adverse reaction that can occur with use of this drug is a heavy loss of sodium. Common signs and symptoms of this reaction include:

  • Confusion or a decrease in mental activity

Less common signs and symptoms of sodium loss include:

  • Skin blisters

Rare signs and symptoms of this condition include:

  • Pain in the lower back or side

If you experience any of signs or symptoms of extreme potassium or sodium loss, contact your doctor as soon as possible. Both can lead to more serious problems down the road and your doctor will either change your dosage or find another medication to treat you with.

It is possible that effects not included in the above lists could occur while taking hydralazine and hydrochlorothiazide. Talk to your doctor about any effect you may notice that are not mentioned here.

Severe allergic reactions are rare, but can occur when someone with an allergy to some of the inactive ingredients in hydralazine and hydrochlorothiazide takes this medication. Seek immediate medical attention if you or a loved one experience any of the following symptoms after taking a dose:


Exact dosage information and instructions for taking this medicine will vary, depending on the dosage your doctor believes is going to be the most effective for you and your condition. A doctor will make the decisions about specific dosages and the instructions for taking them based on the medical condition this drug is being prescribed for, other medicines and supplements the patient might be taking at the time, other medical conditions the patient has and lifestyle choices the patient is making.

Drug manufacturers will typically include recommended instructions for taking their medication. These instructions are based on their knowledge of the condition and the drug's intended effect. However, it is up to the doctor giving it to their patient to decide more precisely the dosage that will be most effective.

The manufacturer recommends that adults taking hydralazine and hydrochlorothiazide for high blood pressure should take one capsule two times each day, preferably twelve hours apart. For children under the age of eighteen, your doctor will determine how often it should be used, as well as how much at a time.

Should you miss taking a dose of this medication at its scheduled time, take it as soon as possible after realizing you missed it. However, if you do not realize you've missed it until it's close to the time you should take the next dose, then skip the missed dose and take the next one at its normal time. Do not try to catch up on dosages by doubling up.

As with all medications, follow your doctor's directions when taking hydralazine and hydrochlorothiazide. While the manufacturer provides general recommendations for how to take it, your doctor's instructions when they write the prescription are based on their knowledge of you and your specific medical condition.

Therefore, you should not take any more of this medication than directed. You should also not take any less. Do not double up on doses of this medication. Do not take any more than the maximum recommended amount in a day.


Ideally, Hydralazine and hydrochlorothiazide is intended to help lower blood pressure and reduce the amount of water in the body. However, there are a variety of factors that can interact with this medication and modify the effect it is intended to have.

Drug interactions

The list of drugs that could possibly interact with hydralazine and hydrochlorothiazide includes:

  • Allergy medications with diphenhydramine

Food and drink

Patients taking this medication should moderate their alcohol intake levels, as alcohol in combination with hydralazine and hydrochlorothiazide has been known to lower blood pressure to dangerous levels. They should also be cautious about eating foods with high levels of cholesterol, as the diuretic component of this medication can raise triglyceride and cholesterol levels.


There are more than a dozen medical conditions that are known to interact with hydralazine and hydrochlorothiazide. These conditions include:

  • Anuria

This is not a complete list of interactions that can take place while using hydralazine and hydrochlorothiazide. Talk to your doctor about all of the medications (prescription and over the counter) and supplements you are currently taking, as well as your diet, exercise habits and other medical conditions you have before you start taking this drug. Your doctor may have advice for how to cope with some of the reactions. They may also modify your dosage levels or decide to give you a different medication, depending on your circumstances.


While you are taking this medication, it is important to visit your doctor at regular intervals so they can check your progress and make certain that this medication is having the intended effects on your body. Blood tests may be needed.

Do not drive, use machinery or perform any other tasks that can be considered dangerous until you know what effect hydralazine and hydrochlorothiazide will have on your body. This medication can give you headaches and make you feel drowsy, dizzy or less alert than you need to be in order to perform these specific kinds of tasks.

Do not take other medications unless you have discussed doing so with your doctor. This includes any over the counter medicines for controlling your appetite, asthmas, coughing and colds, hay fever and sinus problems, because these medications can increase your blood pressure.

Talk to your doctor about taking this medication if there is a history of diabetes in your family, as it may be lying latent in your body and can be triggered by elements of this medication.

Be careful about taking this medication if you have coronary artery disease, as it might trigger myocardial ischemia or myocardial infractions. Also use caution if you have mitral valvular disease, as it can increase pulmonary artery pressure. It is also possible that hypotension can occur with use of this medication.

Talk to your doctor about taking hydralazine and hydrochlorothiazide if you have certain renal function disorders, as this medication can increase renal blood flow. Talk to your doctor about stopping the use of this medication if you find yourself experiencing progressive renal impairment.

Let your doctor know if you begin experiencing problems with your peripheral vision as a result of taking this medication. There may be other medications they want you to take to combat this effect.

Talk to your doctor about taking this medication if you have impaired hepatic function or progressive liver disease, as potentially serious adverse reactions can occur with the use of this medication.

Talk to your doctor if you are already taking antihypertension medications, as these may cause an adverse reaction.

Be careful about using hydralazine and hydrochlorothiazide if your family has a medical history of systemic lupus erythematosus, as this medication can activate the condition if you have not been diagnosed, or exacerbate the condition if you already have it.

You may experience dizziness, lightheadedness or fainting while taking hydralazine and hydrochlorothiazide, especially if you are just getting up from a sitting or lying position. This issue is most likely to occur in the morning. To remedy this, sit on the edge of the bed and leave your feet dangling for one to two minutes before standing up slowly. If this becomes a persistent problem or gets worse, talk to your doctor.

You may also experience dizziness, lightheadedness or fainting if the weather is too warm, or if you drink alcohol, stand for too long, or exercise. Watch the amount of alcohol you drink carefully, and be extra cautious while outside in the heat or during your exercise time if either requires you to stand for longer periods of time.

Hydralazine and hydrochlorothiazide can cause your body to lose potassium. In order to help prevent this from happening, your doctor might recommend that you do the following:

  • Eat or drink foods with high levels of potassium (especially oranges or other citrus fruit juices)

Follow these directions if your doctor gives them to you and do not change your diet without talking to your doctor first, especially if they already have you on a special diet, potassium supplements, or some kind of medication that reduces potassium loss.

Talk to your doctor if you feel sick and are having severe or continuing nausea, diarrhea or vomiting, as these problems can cause you to lose more water and potassium.

If you have diabetes and are using this medication, you should be especially careful about having your blood and urine tested for sugar levels. Talk to your doctor if you have any questions or concerns about this.

Tell your doctor if you are allergic to hydralazine and hydrochlorothiazide or any other medication.

You may experience greater sensitivity to sunlight while on this medication, so be careful about how much time you spend outside during the day. Exposure to sunlight may cause severe sunburn, skin rash, redness, itching or discoloration, or changes in your vision.

Stay out of direct sunlight, especially between 10 am and 3 pm, if you can. Wear protective clothing (including a hat and sunglasses). Use sun block with at least an SPF of 15, or higher if your complexion is fair. Avoid using sunlamps, tanning beds, and tanning booths while on this medication.

Before undergoing surgery (medical or dental) or any kind of emergency medical treatment, tell the doctor or dentist in charge of your care that you are taking hydralazine and hydrochlorothiazide.

Do not take hydralazine and hydrochlorothiazide at the beginning of your treatment for hypertension.

Talk to your doctor about using this medication if you are pregnant or planning to become pregnant, as there is the risk of asymptomatic and symptomatic thrombocytopenia, lupus-like toxicity levels and metabolic risk in the mother and child, malformations and labor difficulties.

Do not take hydralazine and hydrochlorothiazide while you are nursing, as this medication is excreted into human milk. There are potentially serious adverse reactions to this medication in nursing infants. Nursing mothers should plan to either discontinue their use of the medication until they are finished nursing or stop nursing, depending on the conversation they have with their doctor.


Store your prescription for hydralazine and hydrochlorothiazide in a tightly sealed container in a space that remains at room temperature (between 60-86 degrees Fahrenheit or 15-20 degrees Celsius).

Do not store keep this medicine cold. Do not keep it in places like the refrigerator, freezer, or rooms in your home that are difficult to heat.

Keep this medication away from sources of heat, like the stove or oven in your kitchen. Also keep it away from sources of moisture, like a sink or shower in the bathroom. Do not store it in places in the house that receive direct sunlight, like a windowsill or counter underneath a window.

When you have finished treatment with hydralazine and hydrochlorothiazide or when the medication is past its expiration date, you should make plans to properly dispose of it. Do not hold onto extra doses once you have finished taking it.

Do not dispose of this medication by flushing it down the toilet. Also, do not dispose of it by pouring it down the sink.

If you have questions about the right way to dispose of this drug once you are finished with it, ask your doctor.


Hydralazine and hydrochlorothiazide is a combination blood pressure and diuretic medication that is used as part of an overall treatment plan for patients with high blood pressure. It helps make the workload easier for blood vessels throughout the body and helps rid the body of extra water that may not be making its way out.

It can prevent further damage from being done to various parts of the body, as well as preventing future life-threatening conditions, like heart attacks, stroke, and kidney disease. It is not designed for patients who are just starting treatment for hypertension, but is designed to help your heart and the hardworking blood vessels in your body relax so they are able to do their jobs for longer.

While this medication is generally beneficial to the process of treating high blood pressure, there are numerous risks involved with using it that can only be ascertained by a doctor who has accurate and complete knowledge of a patient's medical history. This cannot occur when patients do not disclose their full medical history to their doctor prior to starting treatment.

It is imperative that patients are open and honest with their doctors and willing to discuss everything they know about their current medical condition and their medical history. There is a long list of medications, medical conditions, and dietary and lifestyle choices that can have negative interactions with hydralazine and hydrochlorothiazide. A doctor with thorough knowledge of their patient's medical history and current condition can anticipate whatever challenges these interactions create and help their patient design a plan that effectively manages or even prevents them from occurring.

When used correctly, hydralazine and hydrochlorothiazide are an effective part of treating high blood pressure. High blood pressure can take a huge toll on the body, but with the right medical team working together and the right treatment plan in place, patients will be able to have a much greater quality of life for much longer than they might have otherwise. It is even possible that the treatment plan as a whole can cure this condition.