What is Triamterene-HCTZ: Uses, Warnings & Interactions

Updated Aug 26, 2025  •  Published Dec 30, 2020

Triamterene-HCTZ is a combination diuretic, a type of medicine that increases urination and eliminates water and salts. One of the drugs (hydrochlorothiazide) is a thiazide diuretic and is commonly prescribed for high blood pressure. Triamterene is a potassium-sparing diuretic that is often used when low potassium is an issue or a risk. Triamterene-HCTZ tablets or capsules are taken once daily without regard to food.

Triamterene-HCTZ overview

BRAND NAMES:

  • No brand-name versions

Generic Names:

  • Triamterene-hydrochlorothiazide, triamterene HCTZ

Uses:

  • Treats fluid retention (edema) and high blood pressure.

Therapeutic Classes:

  • Diuretic, potassium-sparing/thiazide combination

Forms:

  • Tablet, capsule

How it’s taken:

  • By mouth

What is Triamterene-HCTZ used for?

Triamterene-HCTZ is a prescription generic drug that treats fluid retention and high blood pressure. It is usually prescribed to people who develop low potassium when taking only hydrochlorothiazide.

What form(s) does Triamterene-HCTZ come in

  • Tablet

    • 37.5 mg triamterene/25 mg hydrochlorothiazide

    • 75mg/50 mg

  • Capsule

    • 37.5mg/25 mg

    • 50 mg/25 mg

What are common Triamterene-HCTZ doses?

  • For high blood pressure: One to two tablets or capsules once daily

  • For fluid retention: One to two tablets or capsules once daily

Common Triamterene-HCTZ prescriptions

  • Triamterene-HCTZ
    37.5-25mg capsule

  • Triamterene-HCTZ
    50-25mg capsule

  • Triamterene-HCTZ
    37.5-25mg tablet

  • Triamterene-HCTZ
    75-50mg tablet

How to take Triamterene-HCTZ

  • Follow all the prescriber’s instructions.

  • Take only one dose daily with or without food.

  • Swallow the tablet or capsule whole with a drink of water. Do not break, crush, or chew it.

  • Store the medicine in a closed container at room temperature away from light and moisture.

What to do if you miss a dose of Triamterene-HCTZ

  • Take a dose as soon as you remember.

  • If it is almost time for your next dose, wait until then and take a regular dose.

  • Do not take extra medicine to make up for a missed dose.

Triamterene-HCTZ contraindications

  • This medicine is not right for everyone. 

  • Do not use it if you have had an allergic reaction to triamterene, hydrochlorothiazide, or a sulfa drug. 

  • Trimaterene is also contraindicated in people:

    • Unable to urinate

    • Have severe kidney disease

    • Have high potassium levels 

Triamterene-HCTZ warnings

  • Tell any healthcare provider or dentist who treats you that you are using this medicine.

  • Triamterene-HCTZ treatment requires regular check-ups and blood tests to monitor the effectiveness and safety of the treatment. Keep all appointments.

  • Before starting triamterene-HCTZ, tell the prescriber if you are pregnant, breastfeeding, or if you have:

    • Liver disease, especially cirrhosis of the liver

    • Electrolyte imbalances

    • Heart rhythm abnormalities

    • Diabetes

    • Gout

    • Lupus

    • A history of kidney stones

    • Parathyroid gland problems

    • Low folic acid levels

  • This medicine can cause serious side effects, including: 

    • Electrolyte imbalances

    • Kidney problems, including kidney stones

    • Narrow-angle glaucoma

    • High uric acid levels

    • New or worsening gout

    • Increased risk of skin cancer

  • This medicine could lower your blood pressure too much and make you dizzy, lightheaded, or faint. 

    • Sit or lie down if you feel dizzy. 

    • Do not drive or engage in risky activities until you know how this medicine affects you.

  • Drink plenty of fluids if you exercise, sweat more than usual, or have diarrhea or vomiting while you are using this medicine.

  • This medicine can increase the risk of skin cancer. 

    • Wear sunscreen or protective clothing when exposed to the sun. 

    • Do not use sunlamps or tanning beds.

Triamterene-HCTZ interactions

  • Never use triamterene-HCTZ with:

    • Other potassium-sparing diuretics

    • Potassium supplements or salt substitutes (except in people with low potassium)

  • To avoid potentially hazardous drug interactions, tell the prescribing healthcare provider about all prescription drugs, over-the-counter medications, and supplements regularly used, particularly:

    • Other diuretics

    • Laxatives

    • Blood pressure drugs, including ACE inhibitors

    • NSAIDs, particularly indomethacin

    • Drugs that affect heart rhythms

    • Diabetes medications

    • Drugs that make you sleepy, such as narcotic pain relievers or sleeping pills

  • Ask your doctor or healthcare provider before you use any medicine, supplement, or salt substitute that contains potassium.

  • Avoid alcohol unless you’ve consulted with the prescriber.

  • Tell any doctor or healthcare provider who treats you that you are using this medicine. 

Triamterene-HCTZ side effects

Serious side effects

Talk to a healthcare provider if you notice any signs or symptoms of a possible serious side effect:

  • Dry mouth, increased thirst, muscle cramps

  • Confusion, weakness, uneven heartbeat, trouble breathing, numbness or tingling in your hands, feet, or lips

  • Chest pain, palpitations, nausea, muscle weakness

  • Nausea, vomiting, headache, fatigue, confusion, low energy, irritability

  • Sudden and severe stomach pain, nausea, vomiting, fever, lightheadedness

  • Lightheadedness, dizziness, or fainting

  • Fast, pounding, or uneven heartbeat

  • Change in how much or how often you urinate, problems urinating, pain in your side or lower back

  • Yellow skin or eyes

  • Unusual bleeding, bruising, or weakness

  • Blurred vision, sudden eye pain, swelling or redness in one eye

  • Possible skin cancer: sores, reddish patch or irritated area, shiny bump, pink growth, or white, yellow or waxy scar-like area on the skin

  • Drug reaction: blistering, peeling, skin rash

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

Some serious side effects may have no symptoms. Regular blood tests are required to spot these problems before they become symptomatic:

  • High potassium

  • High calcium

  • Low sodium

  • Low chloride

  • Low magnesium

  • Low phosphate

  • High blood sugar

  • High uric acid

  • Liver dysfunction

  • Elevated cholesterol and fats

Less serious side effects

  • Dizziness

  • Fatigue

  • Headache

  • Dry mouth

Sources:

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