Drug & supplement interaction

Quassia + Furosemide

Furosemide brand name: Lasix.

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

Quassia has a moderate interaction with Furosemide. Overuse of quassia might compound diuretic-induced potassium loss.

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

Quassia and Furosemide

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

Moderate

DIURETIC DRUGS

Why this applies to Furosemide

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

Overuse of quassia might compound diuretic-induced potassium loss. There is some concern that people taking quassia along with potassium depleting diuretics might have an increased risk for hypokalemia. Initiation of potassium supplementation or an increase in potassium supplement dose may be necessary for some patients.
Some diuretics that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), and hydrochlorothiazide (HCTZ, Hydrodiuril, Microzide), and others.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

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

Here's the gist with furosemide (Lasix) and quassia. Lasix already pushes your kidneys to flush out water and salt, and along the way it can drag potassium out too. The worry on file is that large amounts of quassia might add to that potassium loss, so the two together could nudge your potassium lower than Lasix alone would.

Low potassium can show up as muscle cramps, weakness, fatigue, or an irregular heartbeat. I'll be honest though: this concern is theoretical, based on how the herb is thought to behave rather than solid human studies, and a tiny bitter taste is unlikely to matter much. If you take Lasix regularly and are thinking about concentrated quassia supplements, check in with your pharmacist or doctor first, especially if your potassium is ever monitored.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Robbers JE, Speedie MK, Tyler VE. Pharmacognosy and Pharmacobiotechnology. Baltimore, MD: Williams & Wilkins, 1996.

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

Quassia Also Interacts With Other Medications

Quassia has 161 moderate, 36 minor 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.

Moderate 161 Minor 36 No known interaction 2,633 (incl. Furosemide)
Taking anything else?

Check Another of Your Medications Against Quassia

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

From our Q&A

Questions About Quassia 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 Quassia 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 Quassia 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 Lithium (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 Quassia as Part of a Dietary Supplement Product? Check It for Interactions

We hold 172 real supplement products containing Quassia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Quassia. Your product may carry other ingredients that interact with Furosemide too, on top of Quassia — 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 Quassia 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 Quassia
Top half

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

29 days ago today
Medication Furosemide
Steady interest

#1,540 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 Quassia

What is Quassia?

  • Loss of appetite
  • Digestive upset
  • Head lice (topical)
  • Intestinal worms/parasites
  • Bitter tonic

Quassia is a tropical wood known for its very bitter taste, traditionally used as a digestive bitter and as a folk remedy for parasites and head lice. Human evidence for these uses is limited, and high doses may irritate the stomach, so it should be used cautiously and avoided in pregnancy.

Read the full Quassia 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 & Quassia

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

0Major
161Moderate
36Minor
2,632No known interaction
161 Moderate 36 Minor 2,632 No interaction
Moderate

161 interactions

Showing 60 of 161 moderate interactions — see all 161 on the Quassia page.

Minor

36 interactions

No interaction 2,632 drugs checked — show the list

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

Showing the 60 most looked-up of 2,632 medications checked with no known interaction — see the full Quassia list.

See the full Quassia 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
Quassia 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 Quassia and Furosemide Together: Common Questions

Can you take Quassia with Furosemide?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Quassia and Furosemide interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Furosemide and Quassia?

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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.