Worst Pills, Best Pills

An expert, independent second opinion on more than 1,800 prescription drugs, over-the-counter medications, and supplements

Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: hydralazine (hy DRAL a zeen)
Brand name(s): APRESOLINE
GENERIC: available FAMILY: Other Drugs for High Blood Pressure
Find the drug label by searching at DailyMed.

Limited Use [what does this mean?]
Generic drug name: hydralazine and hydrochlorothiazide (hye DRAL a zeen and hye droe klor oh THYE a zide)
GENERIC: available FAMILIES: Other Drugs for High Blood Pressure, Thiazide Diuretics
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

Hydralazine caused fetal harm in animal studies, including malformation of the bones of the face and head as well as cleft palate. Because of the potential for serious adverse effects to the fetus, this drug should not be used by pregnant women.

Breast-feeding Warning

No information is available from either human or animal studies. However, it is likely that this drug, like many others, is excreted in human milk, and because of the potential for serious adverse effects in nursing infants, you should not take this drug while nursing.

Safety Warnings For This Drug [top]


A fixed-combination drug should not be the first drug used to treat your high blood pressure. You may not need more than one drug. If you do need two drugs, the fixed-combination product may not contain the dose of each drug that is right for you. Your doctor has to regularly check your condition and reevaluate the effect of the drug(s) you take. This may mean adjusting doses, and even changing drugs, to ensure proper treatment. This fixed-combination drug may be the best drug for you, but it should be used only after you have tried each of its ingredients separately, in varying doses. If the doses that you need to control your high blood pressure match those in this fixed-combination product, use it if the combination drug is more convenient.

Facts About This Drug [top]

Hydralazine (APRESOLINE) was first approved for marketing in the U.S. in 1953. It is used to treat high blood pressure (hypertension), but it is not the first-choice drug for this purpose. People with coronary artery disease should not use hydralazine at all.[1]

Public Citizen lists these drugs for Limited Use.

The starting dose of hydralazine should be between 10 and 12.5 milligrams (mg), four times a day. The total daily dose should not exceed 150 to 200 mg.[2] If you have impaired...

Hydralazine (APRESOLINE) was first approved for marketing in the U.S. in 1953. It is used to treat high blood pressure (hypertension), but it is not the first-choice drug for this purpose. People with coronary artery disease should not use hydralazine at all.[1]

Public Citizen lists these drugs for Limited Use.

The starting dose of hydralazine should be between 10 and 12.5 milligrams (mg), four times a day. The total daily dose should not exceed 150 to 200 mg.[2] If you have impaired kidney function, you should be taking a smaller dose.

Side effects

Frequent severe adverse effects seen with hydralazine include rapid heart rate, worsening of chest pain, headache, dizziness, fluid retention, nasal congestion, lupus-like syndrome and inflammation of the liver (hepatitis).[1]

First-line treatment for high blood pressure

If you have high blood pressure, the best way to reduce or eliminate your need for medication is by improving your diet, losing weight, exercising and decreasing your salt and alcohol intake. Mild hypertension can be controlled by proper nutrition and exercise. If these measures do not lower your blood pressure enough and you need medication, hydrochlorothiazide (ESIDRIX, HYDRODIURIL, MICROZIDE) or chlorthalidone (HYGROTON) ,  water pills, should be used first, starting with a low dose of 12.5 milligrams daily. These drugs also cost much less than other blood-pressure drugs. 

There is growing evidence that thiazide diuretics, such as hydrochlorothiazide, significantly decrease the rate of bone mineral loss in both men and women because they reduce the amount of calcium lost in the urine.[3] Research now suggests that thiazide diuretics may protect against hip fracture.[4]

If your high blood pressure is more severe, and hydrochlorothiazide alone does not control it, a drug in another family of high-blood-pressure-lowering drugs may be added to your treatment. In this case, your doctor would prescribe the hydrochlorothiazide and the second drug separately, with the dose of each drug adjusted to meet your needs, rather than using a product that combines the drug in a fixed combination.

Whatever drugs you take for high blood pressure, once your blood pressure has been normal for a year or more, a cautious decrease in dose and renewed attention to nondrug treatment may be worth trying, according to The Medical Letter on Drugs and Therapeutics.[5]

An editorial in the British Medical Journal stated:

Treatment of hypertension is part of preventive medicine and like all preventive strategies, its progress should be regularly reviewed by whoever initiates it. Many problems could be avoided by not starting antihypertensive treatment until after prolonged observation. ... Patients should no longer be told that treatment is necessarily for life: the possibility of reducing or stopping treatment should be mentioned at the outset.[6]

Regulatory actions surrounding hydrochlorothiazide

2011: In March, the Food and Drug Administration (FDA) issued the following warning concerning the use of hydrochlorothiazide products:

Hydrochlorothiazide, a sulfonamide, can cause an idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma. Symptoms include acute onset of decreased visual acuity or ocular pain and typically occur within hours to weeks of drug initiation. Untreated acute angle-closure glaucoma can lead to permanent vision loss. The primary treatment is to discontinue hydrochlorothiazide as rapidly as possible. Prompt medical or surgical treatments may need to be considered if the intraocular pressure remains uncontrolled. Risk factors for developing acute angle-closure glaucoma may include a history of sulfonamide or penicillin allergy.[7]

Before You Use This Drug [top]

Do not use if you have or have had:

  • aortic aneurysm
  • disease of the arteries that nourish the heart
  • disease of the blood vessels that nourish the brain
  • rheumatic heart disease
  • severe heart disease
  • severe kidney disease
  • pregnancy or are breast-feeding
  • phenylketonuria (if you take the solution)

Tell your doctor if you have or have had:

  • allergies to drugs
  • heart or blood vessel disease
  • kidney disease
  • stroke

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Until you know how you react to this drug, do not drive or perform other activities requiring alertness.
  • Do not stop taking this drug suddenly. Your doctor must give you a schedule to decrease your dose gradually.
  • You may feel dizzy when rising from a lying or sitting position. When getting out of bed, hang your legs over the side of the bed for a few minutes, then get up slowly. When getting up from a chair, get up slowly and stay beside the chair until you are sure that you are not dizzy.
  • If you plan to have any surgery, including dental, tell your doctor that you take this drug.
  • Do not take other drugs without talking to your doctor first—especially nonprescription drugs for appetite control, asthma, colds, coughs, hay fever, or sinus problems.
  • You may need more vitamin B6 (pyridoxine) than usual. Ask your doctor about getting more vitamin B6 in your diet or about taking a supplement.
  • Do not drink alcohol.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Take with food.
  • This medication can be taken whole or broken, chewed or crushed.
  • Crush tablet and mix with food or drink, or swallow whole with water. The liquid form of the drug may be mixed with fruit juice or applesauce just prior to use.
  • Keep the liquid form in the refrigerator. Do not use it after 14 days or if its color changes; replace it.
  • Do not store tablets in the bathroom. Do not expose to heat, moisture, or strong light.
  • Call your doctor if you miss two doses in a row.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:


Adverse Effects [top]

Call your doctor immediately if you experience:

  • blisters on skin
  • chest pain
  • general discomfort or weakness
  • muscle or joint pain
  • numbness, tingling, pain, or weakness in hands and feet
  • skin rash or itching
  • sore throat and fever
  • swelling of feet or lower legs
  • swelling of lymph glands
  • fever

Call your doctor if these symptoms continue:

  • diarrhea
  • constipation
  • loss of appetite
  • nausea, vomiting
  • rapid or irregular heartbeat
  • redness or flushing of face
  • shortness of breath on exertion
  • dizziness, lightheadedness
  • watering or irritated eyes
  • headache
  • stuffy nose (do not take any medication for this)

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • blood pressure
  • antinuclear antibody titer
  • complete blood count
  • direct Coombs’ test
  • lupus erythematosus (LE) cell preparation

last reviewed March 31, 2024