👤 By the CinnaRN Clinical Content Team🕐 Updated 2026-08-23🏷️ Pharmacological Therapies🔖 Free to read, print, and share
Also known as: loop diuretics · furosemide · Lasix · bumetanide · water pills · fluid pills
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Use this quick-reference guide to spot, treat, and prevent Loop Diuretics on the NCLEX. Keep it handy during review and on exam day!
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📒 The 1-minute cheat sheet
🧪 Meds
Furosemide, bumetanide, torsemide
Loop of Henle → ↑ urine output
🧪 Labs
HYPOkalemia: K+ < 3.5 mEq/L
↓ Na+, ↓ Mg, ↓ Ca, dehydration
✅ Do
Give in AM, monitor I&O + weight
Encourage K+-rich foods
🚩 Report
Digoxin toxicity risk if ↓ K+
Ototoxicity, muscle cramps, ↓ BP
📚 Loop Diuretics — full study notes
The cheat sheet above is your quick recall card. These notes go deeper — what it is, what to do first, what must be reported, and what to teach.
Loop diuretics (furosemide/Lasix, bumetanide, torsemide) act on the loop of Henle to produce rapid, potent diuresis by blocking sodium, potassium, and chloride reabsorption. They are used for edema, heart failure, and pulmonary edema. Memory aid: Lasix 'lasts six hours' and dumps potassium, so it is a strong potassium-wasting water pill.
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Key points
Understand these first
They cause potent diuresis and can rapidly relieve pulmonary edema and fluid overload.
They waste potassium, so hypokalemia is the major electrolyte risk, along with hyponatremia, hypocalcemia, and hypomagnesemia.
Rapid IV administration of furosemide can cause ototoxicity and hearing loss.
They can cause dehydration, orthostatic hypotension, and increased BUN/creatinine.
Hypokalemia increases the risk of digoxin toxicity in patients also taking digoxin.
They raise blood glucose and uric acid levels.
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Nursing priorities
What to do, in order
Monitor daily weight, intake and output, and fluid status as the key indicators of effectiveness.
Monitor serum potassium and other electrolytes and replace potassium as ordered.
Administer IV furosemide slowly (no faster than 20 mg/min) to prevent ototoxicity.
Monitor blood pressure for hypotension and implement fall precautions.
Give morning doses to avoid nighttime urination and assess for digoxin toxicity if applicable.
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Red flags — report now
Escalate immediately
Serum potassium below 3.5 mEq/L, especially with muscle weakness or cardiac dysrhythmias.
Signs of severe dehydration or hypotension such as dizziness, weak pulse, and decreased urine output.
New hearing loss or tinnitus suggesting ototoxicity.
Signs of digoxin toxicity when given concurrently with digoxin.
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Labs & values
Numbers to know
Potassium (3.5-5.0 mEq/L) - watch for hypokalemia
Sodium (135-145 mEq/L)
BUN (10-20 mg/dL) and creatinine (0.6-1.2 mg/dL)
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Patient teaching
What patients must know
Weigh yourself daily and report a gain of 2-3 pounds in a day or 5 pounds in a week.
Eat potassium-rich foods such as bananas, oranges, and potatoes unless told otherwise.
Change positions slowly and take the dose in the morning to avoid nighttime urination.
❓ Loop Diuretics: NCLEX FAQs
What are the priority nursing interventions for Loop Diuretics?
Monitor daily weight, intake and output, and fluid status as the key indicators of effectiveness. Monitor serum potassium and other electrolytes and replace potassium as ordered. Administer IV furosemide slowly (no faster than 20 mg/min) to prevent ototoxicity. Monitor blood pressure for hypotension and implement fall precautions.
What are the warning signs of Loop Diuretics a nurse must report?
Serum potassium below 3.5 mEq/L, especially with muscle weakness or cardiac dysrhythmias. Signs of severe dehydration or hypotension such as dizziness, weak pulse, and decreased urine output. New hearing loss or tinnitus suggesting ototoxicity. Signs of digoxin toxicity when given concurrently with digoxin.
What do I need to know about Loop Diuretics for the NCLEX?
They cause potent diuresis and can rapidly relieve pulmonary edema and fluid overload. They waste potassium, so hypokalemia is the major electrolyte risk, along with hyponatremia, hypocalcemia, and hypomagnesemia. Rapid IV administration of furosemide can cause ototoxicity and hearing loss. They can cause dehydration, orthostatic hypotension, and increased BUN/creatinine.
What patient teaching is important for Loop Diuretics?
Weigh yourself daily and report a gain of 2-3 pounds in a day or 5 pounds in a week. Eat potassium-rich foods such as bananas, oranges, and potatoes unless told otherwise. Change positions slowly and take the dose in the morning to avoid nighttime urination.
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Quick Tip
They cause potent diuresis and can rapidly relieve pulmonary edema and fluid overload.