Generic Name: hydrochlorothiazide (hye dro klor o THY a zide)
Brand Names: Aquazide H, HydroDIURIL, Microzide,

What is HCTZ?

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

HCTZ treats fluid retention (edema) in people with congestive heart failure, cirrhosis of the liver, or kidney disorders, or edema caused by taking steroids or estrogen. This medication is also used to treat high blood pressure (hypertension).

HCTZ may also be used for purposes not listed in this medication guide.

Important information

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

Before using HCTZ, 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 HCTZ.

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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 HCTZ. 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 HCTZ even if you feel fine. High blood pressure often has no symptoms.

Before taking this medicine

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

To make sure you can safely take HCTZ, tell your doctor if you have any of these other conditions:

  • kidney disease;
  • liver disease;
  • glaucoma;

  • asthma or allergies;

  • gout;

  • diabetes; or

  • an allergy to sulfa drugs.

FDA pregnancy category B. HCTZ is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Hydrochlorothiazide can pass into breast milk and may harm a nursing baby. Do not use HCTZ without telling your doctor if you are breast-feeding a baby.

See also: Pregnancy and breastfeeding warnings (in more detail)

How should I take HCTZ?

Take HCTZ exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.

Your doctor may occasionally change your dose to make sure you get the best results.

Your blood pressure will need to be checked often. Visit your doctor regularly.

Your blood and urine may both be tested if you have been vomiting or are dehydrated.

HCTZ can interfere with the results of a thyroid test. Tell any doctor who treats you that you are using a thiazide diuretic.

If you are being treated for high blood pressure, keep using HCTZ even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.

Store HCTZ at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

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, weakness, dizziness, dry mouth, thirst, and muscle pain or weakness.

What should I avoid?

Drinking alcohol can increase certain side effects of HCTZ.

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.

HCTZ side effects

Get emergency medical help if you have any of these signs of an allergic reaction to HCTZ: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop using HCTZ and call your doctor at once if you have a serious side effect such as:

  • eye pain, vision problems;

  • dry mouth, thirst, nausea, vomiting;

  • feeling weak, drowsy, restless, or light-headed;

  • fast or uneven heartbeat;

  • muscle pain or weakness;

  • numbness or tingly feeling;

  • a red, blistering, peeling skin rash; or

  • nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious HCTZ side effects may include:

  • diarrhea;

  • mild stomach pain;

  • constipation; or

  • blurred vision.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

HCTZ dosing information

Usual Adult HCTZ Dose for Edema:

25 to 100 mg orally as a single or divided dose.

Usual Adult HCTZ Dose for Hypertension:

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

Usual Adult HCTZ Dose for Nephrocalcinosis:

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

Usual Adult HCTZ Dose for Osteoporosis:

Initial: 25 mg orally once a day
Maintenance dose: May increase to 50 mg per day

Usual Adult HCTZ Dose for Diabetes Insipidus:

Initial: 50 mg orally once a day
Maintenance dose: May increase to 100 mg per day

What other drugs will affect HCTZ?

Tell your doctor if you regularly use other medicines that make you light-headed (such as cold medicine, pain medication, muscle relaxers, and medicine for seizures, depression or anxiety). They can add to the side effects of HCTZ.

Tell your doctor about all other medicines you use, especially:

  • lithium (Eskalith, Lithobid);

  • digoxin (Lanoxin);

  • cholestyramine (Prevalite, Questran) or colestipol (Colestid);

  • steroids (prednisone and others);

  • other blood pressure medications;

  • NSAIDs (non-steroidal anti-inflammatory drugs) such as aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn, Naprelan, Treximet), celecoxib (Celebrex), diclofenac (Arthrotec, Cambia, Cataflam, Voltaren, Flector Patch, Pennsaid, Solareze), indomethacin (Indocin), meloxicam (Mobic), and others; or

  • insulin or oral diabetes medication.

This list is not complete and other drugs may interact with HCTZ. 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.

Where can I get more information?

  • Your pharmacist can provide more information about HCTZ.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use HCTZ only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects.

Copyright 1996-2014 Cerner Multum, Inc. Version: 9.01. Revision Date: 4/19/2011 10:22:10 AM.

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