Quick facts
| Fact | Furosemide |
|---|---|
| Drug class[1] | Loop diuretic |
| Used for[2][3] | Edema from heart failure, cirrhosis or kidney disease; high blood pressure in adults (by mouth); add-on IV treatment for acute pulmonary edema |
| Boxed warning[2] | Too much can cause profound fluid loss and electrolyte depletion |
| Check before giving[1][2] | Blood pressure, potassium and other electrolytes, BUN and creatinine, intake and output, daily weight |
| Timing by mouth[2] | Diuresis starts within 1 hour, peaks in hour 1 or 2, and lasts 6 to 8 hours |
| Hearing risk[2][3] | Tinnitus and hearing loss, more likely with rapid IV injection, severe kidney impairment or other ear-toxic drugs |
Before giving furosemide: potassium, blood pressure and fluid status
- Review the potassium first. Loop diuretics often deplete it, and giving one to a patient whose potassium is already low can worsen hypokalemia and trigger a life-threatening arrhythmia.[1]
- Check blood pressure; fluid loss can cause hypotension and orthostatic changes.[1]
- Track intake and output and daily weight, and assess edema, to judge whether the diuresis is working or going too far.[1]
- Make sure the patient is making urine: anuria is a contraindication.[2]
- Look at kidney labs. The label calls for electrolytes (especially potassium), CO2, creatinine and BUN often during the first few months, then periodically.[2]
- Give it in the morning when possible so diuresis doesn't disturb sleep; Open RN advises avoiding evening doses unless the need is urgent.[1]
- Check glucose in patients with diabetes, since furosemide can raise blood glucose.[2]
- Flag interacting drugs: aminoglycosides (more ear toxicity), lithium (toxicity risk), ACE inhibitors or ARBs (severe hypotension and worse kidney function) and indomethacin (may reduce the diuretic effect). Separate sucralfate by at least 2 hours.[2]
Report signs of dehydration, electrolyte loss or a hearing change
- Fluid or electrolyte loss can show up as dry mouth, thirst, weakness, drowsiness, muscle cramps, low urine output, hypotension, a fast heart rate, an arrhythmia, or nausea and vomiting.[2]
- Report ringing in the ears or any hearing change. The label ties furosemide ototoxicity to rapid injection, severe kidney impairment, high doses, low blood protein and other ear-toxic drugs, and the hearing loss can be permanent.[2][3]
- Low potassium matters more in a patient on digoxin, because digitalis can exaggerate its effects on the heart.[2]
- Excessive diuresis may cause dehydration and low blood volume, with a risk of circulatory collapse and possibly blood clots, especially in older adults.[2]
- Patients allergic to sulfonamides may also react to furosemide.[2]
Teach slow position changes, potassium foods and daily weights
- Get up slowly; postural hypotension can happen.[1][2]
- Eat potassium-rich foods. The prescriber may also add a potassium supplement.[1]
- Report a weight gain of more than 3 pounds in a day.[1]
- The skin may burn more easily in sunlight.[2]
- With high blood pressure, skip over-the-counter appetite suppressants and cold products that can raise it.[2]
Practice furosemide, lisinopril, and metoprolol in the Cardiovascular and renal medicines flashcard deck.
Browse flashcardsHow it shows up on nursing exams
- Watch potassium closely when furosemide and digoxin are given together, since low potassium raises the risk of digoxin toxicity.[1]
- Before and after a loop diuretic, the assessments are blood pressure, potassium, kidney function, intake and output, and daily weight.[1]
- Ringing in the ears after a fast IV injection, or with an aminoglycoside antibiotic on board, points to ototoxicity.[2][3]
Practice question
A 70-year-old patient with heart failure and pneumonia on the medical-surgical unit is receiving IV gentamicin. Two hours ago the patient received IV furosemide. Blood pressure is 124/76 mm Hg, heart rate 84/min and this morning's potassium 4.1 mEq/L. Which statement by the patient should the nurse report to the health care provider right away?
- A. "I've needed the urinal four times since the IV dose"
- B. "My breathing feels easier than it did this morning"
- C. "My ankles look less swollen than they did yesterday"
- D. "My ears started ringing about an hour after the dose"
Show the answer and why
Correct answer: D. "My ears started ringing about an hour after the dose"
- A. Incorrect. Frequent urination is the expected effect: furosemide blocks sodium and water reabsorption in the kidney, which increases urine flow.
- B. Incorrect. Easier breathing suggests the diuretic is relieving fluid overload, which is what IV furosemide is given for in heart failure.
- C. Incorrect. Less ankle swelling also points to the intended effect, because furosemide treats edema.
- D. Correct. Tinnitus can be a sign of furosemide ototoxicity, and the risk is higher with aminoglycoside antibiotics such as gentamicin. The hearing loss can be permanent, so this needs prompt reporting.
Sources for this question: [1][2][3][4]
Memory hook: Lasix lasts 6 to 8 hours by mouth, and potassium leaves with the water.