Drug & supplement interaction

Lithium + Furosemide

Furosemide brand name: Lasix.

Major Interaction
Medically reviewed by · Updated September 2026
The bottom line Major

Lithium has a major interaction with Furosemide. Theoretically, taking lithium supplements with loop diuretics might increase lithium levels and adverse effects.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Lithium and Furosemide

Here is the interaction we found between these two, with the evidence behind it.

Major

DIURETIC DRUGS

Why this applies to Furosemide

Furosemide falls under DIURETIC DRUGS — the group Lithium interacts with.

Theoretically, taking lithium supplements with loop diuretics might increase lithium levels and adverse effects.
Thiazide diuretics and loop diuretics might reduce lithium excretion, particularly in sodium-restricted patients. If lithium is clinically indicated and other treatment options are unavailable or inadequate in patients using diuretics, lithium treatment can be initiated with extreme caution. Serum lithium should be measured frequently and the doses used should be the lowest dose ordinarily tolerated. It is unclear if this interaction would be clinically significant with the smaller doses found in lithium supplements.
Severity Major Likelihood Probable Evidence D

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist of pairing a lithium supplement with furosemide (Lasix). Your kidneys clear lithium out of your body, and water pills like furosemide change how your kidneys handle sodium and fluid. The concern is that this can slow down how much lithium you flush out, letting lithium slowly build up in your blood.

Lithium has a narrow safety window, so even a small rise can cause trouble like nausea, tremor, confusion, or unsteadiness. That said, this is a theoretical caution based on how the drugs work, and it's mostly studied with prescription-strength lithium. With the tiny amounts in over-the-counter lithium supplements, it's unclear if it matters at all. Still, please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Martindale W. Martindale the Extra Pharmacopoeia. Pharmaceutical Press, 1999.
  2. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  3. https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/017812s028,018421s027lbl.pdf. Accessed Nov. 21, 2018

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Lithium Also Interacts With Other Medications

Lithium has 258 major, 256 moderate known drug interactions in our database — the Furosemide one above is one of them. If you take anything else, check it against the full list below.

Major 258 Moderate 256 No known interaction 2,316 (incl. Furosemide)
Taking anything else?

Check Another of Your Medications Against Lithium

Covers the 2,830 medications we’ve checked against Lithium. Pick one to open its full report.

From our Q&A

Questions About Lithium or Furosemide

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Lithium or Furosemide, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Furosemide

This page covers Lithium only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Furosemide page lists 227 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Asarabacca (major) and Oleander (major).

By severity: 9 major · 193 moderate · 25 minor.

From our pharmacist’s overview on the Furosemide page

“Yellow dock is where I would start with furosemide (Lasix). This water pill already flushes potassium, and heavy yellow dock use can compound that loss, one of nine major-rated interactions on a list of 227 that deserves genuine care.”

Reviewed by 2 · Jul 18, 2026

Open the Furosemide interaction page

One more smart check

Taking Lithium as Part of a Dietary Supplement Product? Check It for Interactions

We hold 330 real supplement products containing Lithium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lithium. Your product may carry other ingredients that interact with Furosemide too, on top of Lithium — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Lithium and Furosemide Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Lithium
Top 25%

#258 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Furosemide
Steady interest

#1,531 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Lithium

What is Lithium?

Lithium
  • Mood support
  • Bipolar disorder (prescription)
  • Healthy mental function
  • Irritability or stress
  • Sleep support

Lithium is a naturally occurring metal that, in prescription form (lithium carbonate or citrate), is an FDA-approved, well-proven treatment for bipolar disorder. Low-dose supplement forms like lithium orotate are sold for mood support, but there is very little reliable evidence that they work, and even small amounts of lithium can be risky for some people. Always talk to a pharmacist or doctor before taking any lithium product.

Read the full Lithium monograph & all interactions
Medication

About Furosemide

What Is Furosemide Used For?

Brand name: Lasix

Furosemide tablets and oral solution are used in adults and children to treat edema (fluid buildup) caused by congestive heart failure, cirrhosis of the liver, and kidney disease, including nephrotic syndrome. In adults, oral furosemide is also used to treat high blood pressure, alone or alongside other blood pressure medications.

Furosemide injection is reserved for patients who cannot take oral medicine or for emergency situations such as acute pulmonary edema (sudden dangerous fluid in the lungs). Furoscix (subcutaneous injection) is specifically indicated for edema in adults with chronic heart failure or chronic kidney disease, including nephrotic syndrome, and in pediatric patients weighing at least 43 kg. Lasix Onyu (subcutaneous injection) is indicated for edema in adults with chronic heart failure only.

See full Furosemide drug information
Keep checking

Other Drugs & Lithium

Browse every other medication we’ve checked against Lithium — both the ones with a known interaction and the ones without. Select any drug for the full detail.

258Major
256Moderate
0Minor
2,315No known interaction
258 Major 256 Moderate 2,315 No interaction
Major

258 interactions

Showing 60 of 258 major interactions — see all 258 on the Lithium page.

Moderate

256 interactions

Showing 60 of 256 moderate interactions — see all 256 on the Lithium page.

No interaction 2,315 drugs checked — show the list

We also checked Lithium against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,315 medications checked with no known interaction — see the full Lithium list.

See the full Lithium interactions page
See every supplement checked against Furosemide, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Lithium monograph › Uses, safety, and every drug interaction in one place Furosemide supplement interactions › Every supplement checked against Furosemide, ranked by severity Furosemide drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Lithium and Furosemide Together: Common Questions

Can you take Lithium with Furosemide?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Lithium and Furosemide interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Furosemide and Lithium?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.