Causality assessment · Expected pharmacological effect

Furosemide (loop diuretics) and Hypokalaemia: is the FAERS signal real?

n=5,325 co-reports · PRR 6.8 · ROR 6.9

Furosemide (loop diuretics) side-effect profile All assessments See in the full list

A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.

Expected pharmacological effect

Furosemide (loop diuretics) ↔ Hypokalaemia

n=5,325 co-reports · PRR 6.8 · ROR 6.9

Furosemide, a loop diuretic, increases the amount of sodium reaching the distal nephron, where it is exchanged for potassium, so it lowers serum potassium — a direct, dose-related consequence of how it works and a common reason for electrolyte monitoring during diuretic therapy. The risk is greater at higher doses, in older patients, and with other potassium-losing drugs. The very high FAERS count (5,325 co-reports, PRR 6.8) reflects both the real effect and the enormous use of loop diuretics.

Regulatory basis: furosemide prescribing information (hypokalaemia and electrolyte-monitoring warning). Established loop-diuretic literature.

Bradford Hill viewpoint	Status	Note
Temporality (necessary)	met	Potassium falls during treatment and is corrected with replacement/dose adjustment
Strength	met	PRR 7 on a very large co-report count
Consistency	met	Reproduced across diuretic trials
Specificity	met	A class effect, less typical of potassium-sparing diuretics
Biological gradient	partial	Dose-related and worse in older patients
Plausibility	met	Increased distal sodium delivery driving potassium loss is the mechanism
Coherence	met	Coheres with the labelled electrolyte-monitoring advice
Experiment	met	A trial recorded hypokalaemia on furosemide and in none of the comparator arm
Analogy	met	Analogous to hypokalaemia from thiazide and other loop diuretics

This page's own qualitative read, not an automated/citation-gated assessment.

✓ Trial evidence found — Avoiding Treatment in the Hospital With Furoscix for the Management of Congestion in Heart Failure - A Pilot Study (NCT04593823), N=51

Term (as recorded)	Furoscix Infusor (n=34)	Continued Medical Therapy (n=17)
Hypokalaemia — Metabolism and nutrition disorders	7	0

Hypokalaemia was reported in 7 of 34 patients receiving the furosemide infusor versus 0 of 17 on continued oral therapy in this small pilot — directionally consistent with loop-diuretic potassium loss, though too small to estimate a rate. View on ClinicalTrials.gov →