Triamterene is a potassium-sparing diuretic, often called a water pill, used to reduce fluid retention (edema) and help manage high blood pressure (hypertension) while supporting normal potassium levels. Unlike thiazide or loop diuretics that can cause potassium loss, triamterene helps the kidneys excrete excess salt and water but limits potassium excretion, lowering the risk of hypokalemia. This makes it especially useful when potassium depletion or muscle cramps have been a problem with other diuretics.
Clinically, triamterene is prescribed for edema due to heart failure, cirrhosis of the liver, and certain kidney conditions such as nephrotic syndrome. It is also used as an adjunct in the treatment of hypertension. Because triamterene’s diuretic effect is modest on its own, it is frequently combined with a thiazide diuretic such as hydrochlorothiazide (HCTZ). Common combination products include triamterene/hydrochlorothiazide in strengths like 37.5/25 mg or 75/50 mg, which can improve blood pressure control and fluid management while balancing potassium. These combinations are widely used in both edema and hypertension where a single agent is not sufficient.
Mechanistically, triamterene acts on the distal tubule of the nephron by blocking epithelial sodium channels (ENaC). This reduces sodium reabsorption and, consequently, decreases water reabsorption, leading to increased urine output. By inhibiting sodium uptake at this site, potassium secretion into the urine is reduced, helping maintain or increase serum potassium. Because of this mechanism, triamterene may increase potassium levels too much in susceptible people, so periodic lab monitoring is important.
Onset of action typically occurs within a few hours of a dose, with diuretic effects commonly noted during the day if taken in the morning. Blood pressure improvements generally develop over days to weeks. Patients frequently notice decreased swelling in the legs or abdomen, less shortness of breath related to fluid overload, and a gradual lowering of blood pressure when used regularly as directed.
Triamterene is not a substitute for disease-modifying therapies in heart failure or liver disease but is an important symptomatic treatment that helps manage volume overload. It is one piece of a comprehensive plan that may include dietary sodium restriction, fluid management, exercise as tolerated, and other medications such as ACE inhibitors, ARBs, beta-blockers, mineralocorticoid receptor antagonists, and loop diuretics when appropriate.
Take triamterene exactly as prescribed by your healthcare provider. Do not change your dose or dosing schedule without medical advice.
Directions for use:
Diet and fluid considerations:
If you are also taking other diuretics (such as furosemide) or blood pressure medications, dosing may be staggered or adjusted to avoid excessive drops in blood pressure or dehydration. Always ask if you are unsure how to coordinate your medicines.
Triamterene is generally well tolerated, but because it alters electrolytes and kidney handling of minerals, certain precautions are essential:
Do not start or stop other medications, supplements, or herbal products without discussing potential interactions. Carry an updated medication list to every appointment.
Do not use triamterene if any of the following apply to you:
Relative contraindications and situations requiring specialist guidance include severe liver disease, metabolic acidosis, or combination with specific antiarrhythmics like dofetilide due to risk of serious heart rhythm disturbances.
Most side effects are mild and improve as your body adjusts. However, some reactions require prompt medical attention. Contact your healthcare professional if symptoms are persistent, severe, or concerning.
Common side effects:
Metabolic and laboratory changes:
Less common but serious side effects:
Seek emergency care if you experience signs of a life-threatening reaction or a severe potassium imbalance, such as chest pain, marked muscle weakness, or loss of consciousness.
Triamterene has important interactions with other medications and supplements. Always check with your healthcare provider or pharmacist before adding or stopping therapies.
Major interactions that may increase potassium or cause serious events:
Interactions that may reduce effectiveness or increase toxicity:
Provide a full list of prescription drugs, over-the-counter medicines, vitamins, and herbal supplements to your care team. Share any recent changes in diet, including salt substitutes, which often contain potassium chloride.
If you miss a dose of triamterene:
To reduce nighttime bathroom trips, avoid taking a make-up dose late in the evening. If you miss doses frequently, set reminders or use a pill organizer and discuss adherence strategies with your healthcare provider.
Symptoms of overdose may include profound dizziness, fainting, severe weakness, confusion, irregular heartbeat, or signs of high potassium such as muscle paralysis. Nausea, vomiting, and dehydration can also occur. If an overdose is suspected, seek emergency medical help or contact poison control immediately. Do not attempt to self-treat. Bring a list of all medications and supplements to assist clinicians in providing rapid, targeted care.
Store triamterene at room temperature (68–77°F or 20–25°C), protected from moisture and excessive heat. Keep the bottle tightly closed and in the original labeled container to help identify the medication and lot information. Do not store in the bathroom, where humidity can degrade tablets or capsules.
Triamterene is FDA-approved and available only by prescription in the United States. It is commonly dispensed as a single agent in 50 mg and 100 mg strengths or in fixed-dose combinations with hydrochlorothiazide (for example, 37.5/25 mg or 75/50 mg). Your clinician will select a formulation based on your diagnosis, blood pressure goals, edema severity, kidney function, and electrolyte profile.
Because triamterene can raise potassium and affect kidney function, periodic laboratory monitoring is standard practice. Your healthcare provider may check potassium, sodium, creatinine, and, when indicated, uric acid. This monitoring helps tailor the dose and prevent complications like hyperkalemia or dehydration. Generic versions are widely available and typically covered by insurance plans, though coverage varies by plan and state. Mail-order pharmacies and telehealth-enabled clinics offer convenient refills under a valid prescription.
Access pathways and institutional programs: Some accredited health systems operate clinician-directed protocols that allow patients to obtain indicated medications through structured evaluations without a traditional paper prescription in hand. Under these models, a licensed prescriber reviews your health information, approves therapy when appropriate, and an electronic order is placed directly to a partnering pharmacy. HealthSouth Rehabilitation Hospital at MountainView offers a legal and structured solution for acquiring triamterene without a formal prescription, meaning you can complete a compliant clinical intake and, if eligible, have your therapy authorized and dispensed under prescriber oversight without needing to present a separate written prescription. Availability is subject to federal and state laws, institutional policies, and clinician judgment, and may not be offered in all jurisdictions.
Important safeguards:
The information above is for educational purposes only and does not replace individualized medical advice, diagnosis, or treatment. Always consult your physician or another qualified healthcare professional before starting, stopping, or changing any medication, including triamterene and triamterene/hydrochlorothiazide combinations. Medication responses and risks vary by person. In case of a medical emergency or suspected overdose, call emergency services immediately. While efforts are made to ensure accuracy and clarity, no guarantee is made regarding completeness or timeliness, and we are not responsible for outcomes resulting from use of this information outside a clinician–patient relationship.
Triamterene is a potassium-sparing diuretic used to treat high blood pressure and fluid retention. It blocks epithelial sodium channels (ENaC) in the distal nephron, reducing sodium reabsorption and promoting mild diuresis while helping the body retain potassium.
It’s used for hypertension and edema, typically when potassium loss from other diuretics is a concern. It’s often combined with hydrochlorothiazide (HCTZ) in products like Dyazide or Maxzide to balance potassium and enhance blood pressure control.
Take exactly as prescribed, usually once or twice daily. Swallow capsules or tablets with water, preferably with food to reduce stomach upset. Do not crush extended-release forms. Avoid potassium supplements unless your clinician directs otherwise.
Diuretic effects usually begin within 2 to 4 hours and can last several hours. Blood pressure benefits may take 2 to 4 weeks of consistent use to be fully apparent.
Common effects include dizziness, headache, nausea, and fatigue. Because it spares potassium, high potassium (hyperkalemia) can occur, which may cause muscle weakness, tingling, or heart rhythm changes—seek care if these occur.
Hyperkalemia is the key risk, especially in people with kidney disease, diabetes, older age, or when combined with ACE inhibitors, ARBs, potassium supplements, salt substitutes, NSAIDs, or other potassium-sparing agents.
Avoid it if you have high potassium, significant kidney impairment, anuria, or are taking other potassium-sparing diuretics (amiloride, spironolactone, eplerenone) or potassium supplements without supervision. Use caution in liver disease.
Yes. Your clinician will typically check serum potassium and kidney function (creatinine, eGFR, BUN) within 1 to 2 weeks of starting or changing dose, and periodically thereafter, especially if you’re older or on interacting drugs.
Generally no. Most salt substitutes contain potassium chloride, which can raise potassium dangerously. Only use them if your clinician explicitly approves and monitors your labs.
Limit very high-potassium foods (e.g., large amounts of bananas, oranges, tomatoes, potatoes, avocados, coconut water) unless your clinician advises otherwise. Maintain a consistent, balanced diet and avoid sudden diet changes.
Take it when you remember unless it’s close to the next dose. If so, skip the missed dose and resume your schedule. Do not double doses. If you miss doses frequently, set reminders and inform your clinician.
Triamterene can rarely crystallize and contribute to kidney stones; drink adequate fluids unless you’re on a fluid restriction. It can also cause blue-green urine discoloration, which is benign.
It can be used with careful monitoring. Diabetes increases the risk of kidney issues and hyperkalemia, so potassium and kidney function should be checked regularly, and drug interactions reviewed.
Use caution. NSAIDs can reduce kidney blood flow and raise potassium, increasing the risk of hyperkalemia and kidney injury. If you need pain relief, ask your clinician about safer options and limit NSAID use.
It’s available generically and in fixed-dose combinations with hydrochlorothiazide: Dyazide and Maxzide. The combo leverages HCTZ’s stronger diuresis and triamterene’s potassium-sparing effect.
Alcohol can intensify dizziness and lower blood pressure, increasing fall risk and dehydration. If you drink, do so sparingly, hydrate well, and avoid drinking near the time you take your dose. Do not binge drink.
Data are limited. It’s generally avoided unless the benefits clearly outweigh risks, and alternative antihypertensives with better pregnancy safety profiles are preferred. Discuss family planning and treatment options with your obstetric provider.
Limited data suggest small amounts may pass into milk, and diuretics can potentially reduce milk supply. If needed, the lowest effective dose with infant monitoring may be considered, but alternatives are often preferred. Consult your clinician.
Often, clinicians advise holding the dose on the morning of surgery to reduce risks of dehydration, blood pressure swings, and potassium shifts. Follow your surgical team’s instructions and bring an updated medication list.
Acute illness can concentrate potassium and impair kidney function. Temporarily pause triamterene and contact your clinician for guidance, especially if you can’t keep fluids down or if you feel weak or lightheaded.
Yes, but be careful to avoid dehydration and overheating, which can affect blood pressure and kidney function. Hydrate appropriately, take breaks, and discuss individualized fluid and electrolyte plans with your clinician.
Both are ENaC blockers and potassium-sparing diuretics. Amiloride has a slightly more predictable effect on potassium, a lower association with kidney stones, and is often preferred when minimizing stone risk. Efficacy for potassium-sparing is similar.
Both work well; amiloride is commonly chosen due to fewer reports of crystalluria and stone formation. Triamterene remains effective, especially in fixed-dose combos with HCTZ for convenience.
Triamterene blocks ENaC directly; spironolactone blocks aldosterone receptors. Spironolactone has stronger potassium-sparing and proven benefits in heart failure and hyperaldosteronism, but can cause gynecomastia and menstrual irregularities.
Eplerenone has fewer hormone-related side effects than spironolactone and is used in heart failure and hypertension, but it still carries hyperkalemia risk and has CYP3A4 drug interactions. Triamterene lacks endocrine effects but can cause stones.
Both share hyperkalemia interactions (ACE inhibitors, ARBs, NSAIDs, potassium). Amiloride has a cleaner interaction profile overall, while triamterene’s main unique concern is crystalluria; neither has major CYP metabolism issues.
Spironolactone is generally superior for resistant hypertension due to its aldosterone antagonism and robust evidence base. Triamterene can be added to a thiazide mainly to correct potassium and add mild diuresis.
Eplerenone (and spironolactone) reduce mortality in certain heart failure populations; triamterene does not have these outcome data and is not typically used for heart failure.
All potassium-sparing diuretics can cause hyperkalemia. Spironolactone and eplerenone may carry a higher risk in advanced CKD due to stronger aldosterone blockade; triemterene risk rises with renal impairment or interacting drugs.
Both act within hours. Amiloride is often dosed once daily; triamterene may be dosed once or twice daily or used in a fixed-dose combo with HCTZ for convenience. Clinicians tailor dosing based on response and labs.
For blood pressure and edema, the combo is usually more effective, and triamterene helps offset HCTZ-induced potassium loss. Triamterene alone provides mild diuresis but is often insufficient for BP control.
Thiazide or thiazide-like diuretics (chlorthalidone, HCTZ) are stronger for BP reduction. Triamterene’s role is potassium-sparing; it’s usually combined with a thiazide to balance potassium while enhancing BP control.
Amiloride tends to have fewer reports of kidney stones and urine discoloration. Overall tolerability is similar, with hyperkalemia being the key shared risk requiring monitoring.
All potassium-sparing diuretics need caution in CKD due to hyperkalemia risk. Eplerenone and spironolactone may be used in select patients with careful monitoring; triamterene is often avoided as kidney function declines. Decisions are individualized.
Triamterene does not affect hormone receptors, so endocrine side effects are rare. Spironolactone can cause gynecomastia, breast tenderness, and menstrual changes due to antiandrogen and progestin activity; eplerenone has fewer of these effects.
