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HCTZ

Generic name: hydrochlorothiazide (HYE dro KLOR o THY a zide)
Brand name: 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 Sanjai Sinha, MD. Last updated on Sep 30, 2021.

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 is 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.

HCTZ is also used to treat high blood pressure (hypertension).

Warnings

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.

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 HCTZ is safe for you, tell your doctor if you have ever had:

  • kidney disease;

  • liver disease;

  • gout;

  • glaucoma;

  • low levels of potassium or sodium in your blood;

  • high levels of calcium in your blood;

  • a parathyroid gland disorder;

  • diabetes; or

  • an allergy to sulfa drugs or penicillin.

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

You should not breastfeed while using HCTZ.

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

How should I take HCTZ?

Take HCTZ 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 HCTZ, 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 HCTZ. You may need to stop for a short time.

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

HCTZ dosing information

Usual Adult Dose of HCTZ 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 of HCTZ 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 of HCTZ for Nephrocalcinosis:

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

Usual Adult Dose Dose of HCTZ for Osteoporosis:

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

Usual Adult Dose Dose of HCTZ for Diabetes Insipidus:

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

Usual PediatricDose of HCTZ 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 Dose of HCTZ 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 HCTZ 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 HCTZ?

HCTZ 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 HCTZ 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.

HCTZ 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:

  • a light-headed feeling;

  • eye pain, vision problems;

  • jaundice (yellowing of the skin or eyes);

  • pale skin, easy bruising, unusual bleeding (nose, mouth, vagina, or rectum);

  • shortness of breath, wheezing, cough with foamy mucus, chest pain;

  • dehydration symptoms - feeling very thirsty or hot, being unable to urinate, heavy sweating, or hot and dry skin; or

  • signs of an electrolyte imbalance - increased thirst or urination, confusion, vomiting, constipation, muscle pain, leg cramps, bone pain, lack of energy, irregular heartbeats, tingly feeling.

Common hydrochlorothiazide side effects may include:

  • weakness;

  • feeling like you might pass out;

  • severe pain in your upper stomach spreading to your back, nausea and vomiting;

  • fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath; or

  • electrolyte imbalance.

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 HCTZ?

Taking HCTZ 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.

Frequently asked questions

Further information

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.

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