General Use

Thiazide diuretics and loop diuretics are used alone or in combination with other antihypertensives in the treatment of hypertension; they are also used for the treatment of edema due to HF or other causes. Potassium-sparing diuretics have weak diuretic and antihypertensive properties and are used mainly to conserve potassium in patients receiving thiazide or loop diuretics.

General Action and Information

Enhance the selective excretion of various electrolytes and water by affecting renal mechanisms for tubular secretion and reabsorption. Classes commonly used are thiazide diuretics and thiazide-like diuretics (chlorothiazide, chlorthalidone, hydrochlorothiazide, indapamide, and metolazone), loop diuretics (bumetanide, furosemide, and torsemide), and potassium-sparing diuretics (amiloride, spironolactone, and triamterene). Mechanisms vary, depending on agent.


Hypersensitivity. Thiazide and loop diuretics may exhibit cross-sensitivity with other sulfonamides. Potassium-sparing diuretics should be avoided in hyperkalemia or severe renal impairment.


Use with caution in patients with renal or hepatic disease.


Thiazide and loop diuretics may have additive hypokalemia with corticosteroids, amphotericin B, and piperacillin/tazobactam. Hypokalemia may ↑ the risk of digoxin toxicity. Thiazide and loop diuretics may ↑ the risk of lithium toxicity. Additive hypotension with other antihypertensives or nitrates. Potassium-sparing diuretics may cause hyperkalemia when used with potassium supplements, ACE inhibitors, angiotensin II receptor antagonists, and aliskiren.


Assess fluid status throughout therapy. Monitor daily weight, intake and output ratios, amount and location of edema, lung sounds, skin turgor, and mucous membranes.

Assess patient for anorexia, muscle weakness, numbness, tingling, paresthesia, confusion, and excessive thirst. Notify health care professional promptly if these signs of electrolyte imbalance occur.

Hypertension: Monitor BP before and during administration. Monitor frequency of prescription refills to determine compliance in patients treated for hypertension.

Lab Test Considerations: Monitor electrolytes (especially potassium), blood glucose, BUN, serum creatinine, and serum uric acid levels before and periodically throughout course of therapy.


If administering once daily, give in the morning to prevent disruption of sleep cycle. If administering twice daily, give last dose no later than 5 PM to minimize disruption of sleep cycle.

Many diuretics are available in combination with other antihypertensives or potassium-sparing diuretics (see combination_drugs).

Patient/Family Teaching

Instruct patient to take medication exactly as directed. Advise patients on antihypertensive regimen to continue taking medication, even if feeling better. Medication controls, but does not cure, hypertension.

Caution patient to make position changes slowly to minimize orthostatic hypotension. Caution patient that the use of alcohol, exercise during hot weather, or standing for long periods during therapy may enhance orthostatic hypotension.

Instruct patient to consult health care professional regarding dietary potassium guidelines.

Instruct patient to monitor weight weekly and report significant changes.

Caution patient to use sunscreen and protective clothing to prevent photosensitivity reactions with thiazide and loop diuretics.

Advise patient to consult health care professional before taking OTC medication concurrently with this therapy.

Instruct patient to notify health care professional of medication regimen before treatment or surgery.

Advise patient to contact health care professional immediately if muscle weakness, cramps, nausea, dizziness, or numbness or tingling of extremities occurs.

Reinforce the need to continue additional therapies for hypertension (weight loss, regular exercise, restricted sodium intake, stress reduction, moderation of alcohol consumption, and cessation of smoking).

Instruct patients with hypertension in the correct technique for monitoring weekly BP.

Evaluation/Desired Outcomes

Decreased BP.

Increased urine output.

Decreased edema.

Prevention of hypokalemia in patients taking diuretics.