Skip to main content

Hydrochlorothiazide

Generic name: hydrochlorothiazide [ HYE-dro-KLOR-o-THY-a-zide ]
Brand names: HydroDIURIL, Esidrix, Microzide
Dosage forms: oral capsule (12.5 mg), oral tablet (12.5 mg; 25 mg; 50 mg)
Drug class: Thiazide diuretics

Medically reviewed by Melisa Puckey, BPharm. Last updated on Feb 29, 2024.

What is hydrochlorothiazide?

Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.

Hydrochlorothiazide is used to treat high blood pressure (hypertension).

Hydrochlorothiazide is also used to treat fluid retention (edema) in people with congestive heart failure, cirrhosis of the liver, or kidney disorders, or edema caused by taking steroids or estrogen.

Warnings

You should not use hydrochlorothiazide if you are unable to urinate.

Before using hydrochlorothiazide, tell your doctor if you have liver disease, kidney disease, glaucoma, asthma or allergies, gout, diabetes, or if you are allergic to sulfa drugs or penicillin.

Avoid drinking alcohol, which can increase some of the side effects of hydrochlorothiazide .

Avoid becoming overheated or dehydrated during exercise and in hot weather. Follow your doctor's instructions about the type and amount of liquids you should drink. In some cases, drinking too much liquid can be as unsafe as not drinking enough.

There are many other drugs that can interact with hydrochlorothiazide. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor. Keep a list of all your medicines and show it to any healthcare provider who treats you.

If you are being treated for high blood pressure, keep using hydrochlorothiazide even if you feel fine. High blood pressure often has no symptoms.

Before taking this medicine

You should not use hydrochlorothiazide if you are allergic to it, or if you are unable to urinate.

To make sure hydrochlorothiazide is safe for you, tell your doctor if you have ever had:

Tell your doctor if you are pregnant or plan to become pregnant. If you take hydrochlorothiazide during pregnancy, your newborn baby may develop jaundice or other problems.

You should not breastfeed while using this medicine.

Hydrochlorothiazide is not approved for use by anyone younger than 18 years old.

How should I take hydrochlorothiazide?

Take hydrochlorothiazide exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Call your doctor if you have ongoing vomiting or diarrhea, or if you are sweating more than usual. You can easily become dehydrated while taking hydrochlorothiazide, which can lead to severely low blood pressure or a serious electrolyte imbalance.

Your blood pressure will need to be checked often. Your blood and urine may be tested if you have been vomiting or are dehydrated.

If you need surgery, tell your surgeon you currently use this medicine. You may need to stop for a short time.

Keep using hydrochlorothiazide as directed, even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life.

Store at room temperature away from moisture, heat, and freezing. Keep the bottle tightly closed when not in use.

Hydrochlorothiazide dosing information

Usual Adult Dose for Edema:

Usual dose: 25 mg to 100 mg orally once or twice daily

Comments:
-Some patients respond to intermittent therapy, (i.e., administration on alternate days or on 3 to 5 days each week). Excessive response and undesirable electrolyte imbalance are less likely to occur with intermittent dosing.

Usual Adult Dose for Hypertension:

Initial dose: 25 mg orally once daily
Maintenance dose: May increase to 50 mg orally daily, as a single or 2 divided doses

Comments:
-Patients usually do not require doses in excess of 50 mg daily when used concomitantly with other antihypertensive agents.

Usual Adult Dose for Nephrocalcinosis:

Initial: 25 mg orally once daily
Maintenance dose: May increase to 50 mg twice daily

Usual Adult Dose for Osteoporosis:

Initial: 25 mg orally once daily
Maintenance dose: May increase to 50 mg daily

Usual Adult Dose for Diabetes Insipidus:

Initial: 50 mg orally once daily
Maintenance dose: May increase to 100 mg orally daily

Usual Pediatric Dose for Edema:

Less than 6 months: Up to 3 mg/kg/day (up to 1.5 mg/pound) orally in 2 divided doses

Less than 2 years: 1 to 2 mg/kg/day (0.5 to 1 mg/pound) orally daily as a single dose or in 2 divided doses
Maximum dose 37.5 mg per day

2 to 12 years: 1 to 2 mg/kg/day (0.5 to 1 mg/pound) orally daily as a single dose or in 2 divided doses
Maximum dose 100 mg per day

Usual Pediatric Dose for Hypertension:

Less than 6 months: Up to 3 mg/kg/day (up to 1.5 mg/pound) orally in 2 divided doses

Less than 2 years: 1 to 2 mg/kg/day (0.5 to 1 mg/pound) orally daily as a single dose or in 2 divided doses
Maximum dose 37.5 mg per day

2 to 12 years: 1 to 2 mg/kg/day (0.5 to 1 mg/pound) orally daily as a single dose or in 2 divided doses
Maximum dose 100 mg per day

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, dizziness, dry mouth, thirst, and muscle pain or weakness.

What should I avoid while taking hydrochlorothiazide?

Hydrochlorothiazide may increase your risk of skin cancer. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors. Your doctor may want you to have skin examinations on a regular basis.

Drinking alcohol with hydrochlorothiazide can cause side effects.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Avoid becoming overheated or dehydrated during exercise, in hot weather, or by not drinking enough fluids. Follow your doctor's instructions about the type and amount of liquids you should drink. In some cases, drinking too much liquid can be as unsafe as not drinking enough.

Hydrochlorothiazide side effects

Get emergency medical help if you have signs of an allergic reaction to hydrochlorothiazide (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Call your doctor at once if you have:

Common hydrochlorothiazide side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect hydrochlorothiazide?

Taking hydrochlorothiazide with other drugs that make you light-headed can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect hydrochlorothiazide, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Popular FAQ

Research has suggested that taking your blood pressure medication at night instead of in the morning can provide better blood pressure control at night without compromising daytime blood pressure control and reduce your overall risk of dying because of cardiovascular disease by 45%. Continue reading

More FAQ

View more FAQ

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use hydrochlorothiazide only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.