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Hydralazine and Hydrochlorothiazide (Systemic)

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Hydralazine and Hydrochlorothiazide (Systemic)

US Brand Names

• Apresazide


Hydralazine and hydrochlorothiazide (hye-DRAL-a-zeen and hye-droe-klor-oh-THYE-a-zide) combination is used to treat high blood pressure (hypertension).

High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure also may increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Hydralazine works by relaxing blood vessels and increasing the supply of blood and oxygen to the heart while reducing its workload. The hydrochlorothiazide is a type of medicine known as a thiazide diuretic and helps reduce the amount of water in the body by acting on the kidneys to increase the flow of urine.

This medicine is available only with your doctor's prescription, in the following dosage forms:


    • Capsules (U.S.)

Special Considerations

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For hydralazine and hydrochlorothiazide, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to hydralazine, sulfonamides (sulfa drugs), bumetanide, furosemide, acetazolamide, dichlorphenamide, or methazolamide or to hydrochlorothiazide or any of the other thiazide diuretics (water pills). Also tell your health care professional if you are allergic to any other substance, such as foods, preservatives, or dyes.


When hydrochlorothiazide is used during pregnancy, it may cause side effects including jaundice, blood problems, and low potassium in the newborn infant.

Studies with hydralazine have not been done in humans. However, blood problems have been reported in infants of mothers who took hydralazine during pregnancy. In addition, studies in mice have shown that hydralazine causes birth defects (cleft palate, defects in head and face bones); these birth defects may also occur in rabbits, but do not occur in rats.


Hydrochlorothiazide passes into breast milk. However, neither hydralazine nor hydrochlorothiazide has been reported to cause problems in nursing babies.


Although there is no specific information comparing use of this medicine in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults. However, extra caution may be necessary in infants with jaundice, because thiazide diuretics can make this condition worse.

Older adults

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of hydralazine and hydrochlorothiazide combination in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults. However, dizziness or lightheadedness or symptoms of too much potassium loss may be more likely to occur in the elderly, who are usually more sensitive to the effects of this medicine. Also, this medicine may reduce tolerance to cold temperatures in elderly patients.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking hydralazine and hydrochlorothiazide, it is especially important that your health care professional know if you are taking any of the following:

    • Cholestyramine or

    • Colestipol-Use with hydrochlorothiazide may prevent it from working properly; take this combination medicine at least 1 hour before or 4 hours after cholestyramine or colestipol

    • Diazoxide (e.g., Proglycem)-Effect on blood pressure may be increased

    • Digitalis glycosides (heart medicine)-Hydrochlorothiazide may cause low potassium in the blood, which can lead to symptoms of digitalis toxicity

    • Lithium (e.g., Lithane)-Risk of lithium overdose, even at usual doses, may be increased

Other medical problems

The presence of other medical problems may affect the use of hydralazine and hydrochlorothiazide. Make sure you tell your doctor if you have any other medical problems, especially:

    • Diabetes mellitus (sugar diabetes)-Hydrochlorothiazide may change the amount of diabetes medicine needed

    • Gout (history of)-Hydrochlorothiazide may increase the amount of uric acid in the blood, which can lead to gout

    • Heart or blood vessel disease or

    • Stroke (recent)-Lowering blood pressure may make problems resulting from these conditions worse

    • Kidney disease-Hydrochlorothiazide may worsen this condition. Also, the blood pressure lowering effects may be increased because of slower removal of hydralazine from the body

    • Liver disease-If hydrochlorothiazide causes loss of too much water from the body, liver disease can become much worse

    • Lupus erythematosus (history of)-Hydrochlorothiazide may worsen the condition


This medicine may cause you to have an unusual feeling of tiredness when you begin to take it. You may also notice an increase in the amount of urine or in your frequency of urination. After taking the medicine for a while, these effects should lessen. To keep the increase in urine from affecting your sleep:

    • If you are to take a single dose a day, take it in the morning after breakfast.

    • If you are to take more than one dose a day, take the last dose no later than 6 p.m., unless otherwise directed by your doctor.

However, it is best to plan your dose or doses according to a schedule that will least affect your personal activities and sleep. Ask your health care professional to help you plan the best time to take this medicine.

In addition to the use of the medicine your doctor has prescribed, treatment for your high blood pressure may include weight control and care in the types of foods you eat, especially foods high in sodium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.

Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.

Remember that this medicine will not cure your high blood pressure but it does help control it. Therefore, you must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life . If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.

To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.


The dose of hydralazine and hydrochlorothiazide combination will be different for different patients. Follow your doctor's orders or the directions on the label . The following information includes only the average dose of hydralazine and hydrochlorothiazide combination. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules that you take depends on the strength of the medicine.

    • For oral dosage forms (capsules):

      o For high blood pressure:

        Adults-1 capsule two times a day.

        Children-Dose must be determined by your doctor.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


To store this medicine:

    • Keep out of the reach of children.

    • Store away from heat and direct light.

    • Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.

    • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.


It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly.

Do not take other medicines unless they have been discussed with your doctor . This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.

This medicine may cause some people to have headaches or to feel dizzy. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert .

Dizziness, lightheadedness, or fainting may occur, especially when you get up from a lying or sitting position . This is more likely to occur in the morning. Getting up slowly may help . When you get up from lying down, sit on the edge of the bed with your feet dangling for 1 or 2 minutes. Then stand up slowly. If the problem continues or gets worse, check with your doctor.

The dizziness, lightheadedness, or fainting is also more likely to occur if you drink alcohol, stand for a long time, exercise, or if the weather is hot. While you are taking this medicine, be careful in the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for a long time .

This medicine may cause a loss of potassium from your body .

    • To help prevent this, your doctor may want you to:

      o eat or drink foods that have a high potassium content (for example, orange or other citrus fruit juices), or

      o take a potassium supplement, or

      o take another medicine to help prevent the loss of the potassium in the first place.

    • It is very important to follow these directions. Also, it is important not to change your diet on your own. This is more important if you are already on a special diet (as for diabetes), or if you are taking a potassium supplement or a medicine to reduce potassium loss. Extra potassium may not be necessary and, in some cases, too much potassium could be harmful.

Check with your doctor if you become sick and have severe or continuing nausea, vomiting, or diarrhea. These problems may cause you to lose additional water and potassium.

For diabetic patients :

    • Thiazide diuretics may raise blood sugar levels. While you are using this medicine, be especially careful in testing for sugar in your blood or urine. If you have any questions about this, check with your doctor.

Some people who take this medicine may become more sensitive to sunlight than they are normally. Exposure to sunlight, even for brief periods of time, may cause severe sunburn; skin rash, redness, itching, or discoloration; or vision changes. When you begin taking this medicine:

    • Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.

    • Wear protective clothing, including a hat and sunglasses.

    • Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.

    • Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Signs and symptoms of too much potassium loss

Dryness of mouth; increased thirst; irregular heartbeats; mood or mental changes; muscle cramps or pain; weak pulse.

Signs and symptoms of too much sodium loss

Confusion; convulsions; decreased mental activity; irritability; muscle cramps; unusual tiredness or weakness.

Less common

Blisters on skin; chest pain; general feeling of discomfort or illness or weakness; joint pain; numbness, tingling, pain, or weakness in hands or feet; skin rash or itching; sore throat and fever; swelling of the lymph glands.


Lower back or side pain; severe stomach pain with nausea and vomiting; unusual bleeding or bruising; yellow eyes or skin.

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Diarrhea; fast or irregular heartbeat; headache; loss of appetite; nausea or vomiting.

Less common

Constipation; decreased sexual ability; dizziness or lightheadedness, especially when getting up from a lying or sitting position; increased sensitivity of skin to sunlight; redness or flushing of face; shortness of breath with exercise or work; stuffy nose; watering or irritated eyes.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

August 13, 1998

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