NutriStack
Furosemide and Vitamin B1, a synergy.
Long-term furosemide therapy can increase urinary thiamine loss and has been linked with biochemical Vitamin B1 deficiency, especially in heart failure patients taking higher loop-diuretic doses. Deficiency can worsen fatigue, neuropathy, poor appetite, and in severe cases beriberi-like heart failure. Vitamin B1 supplementation can be useful when intake is low, diuretic exposure is high, or deficiency is suspected.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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At a glance
- Substances
- Furosemide and Vitamin B1
- Pair type
- Synergy
- Evidence (highest tier)
- Moderate
- Source citations
- 2 sources
- Stack Score effect
- +2 to your Stack Score (per scored synergy row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Synergy · Moderate evidence
Synergy
What is happening. Long-term furosemide therapy can increase urinary thiamine loss and has been linked with biochemical Vitamin B1 deficiency, especially in heart failure patients taking higher loop-diuretic doses. Deficiency can worsen fatigue, neuropathy, poor appetite, and in severe cases beriberi-like heart failure. Vitamin B1 supplementation can be useful when intake is low, diuretic exposure is high, or deficiency is suspected.
Mechanism. Furosemide-induced diuresis increases urinary excretion of water-soluble thiamine. Replacing Vitamin B1 restores thiamine pyrophosphate needed for carbohydrate metabolism and myocardial energy production.
Recommendation. If you take furosemide chronically, ask whether Vitamin B1 status or empiric low-risk supplementation is appropriate, especially if you have heart failure, poor nutrition, or heavy alcohol use. Do not use thiamine as a substitute for prescribed heart-failure care; use it as monitored nutritional support.
Sources (2)
- Zenuk C, Healey J, Donnelly J, Vaillancourt R, Almalki Y, Smith S. Thiamine deficiency in congestive heart failure patients receiving long term furosemide therapy. Can J Clin Pharmacol. 2003;10(4):184-188. PMID 14712323
- Rieck J, Halkin H, Almog S, Seligman H, Lubetsky A, Olchovsky D, et al. Urinary loss of thiamine is increased by low doses of furosemide in healthy volunteers. J Lab Clin Med. 1999;134(3):238-243. PMID 10482308
Stack Score
How this pair moves the number.
Effect on the composite score
If both Furosemide and Vitamin B1 are in the same stack, this pair applies +2 to your Stack Score (per scored synergy row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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