Drug & supplement interaction

Squill + Quinine

Quinine brand name: Qualaquin.

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

Squill has a moderate interaction with Quinine. Quinine may reduce the clearance of oral digoxin.

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

Squill and Quinine

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

Moderate

QUININE

Quinine may reduce the clearance of oral digoxin. Theoretically, concomitant use of quinine with squill might reduce the clearance of cardiac glycosides found in squill and increase the risk of adverse effects.
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 thing to understand about this pair: it's actually the squill we worry about, not your quinine. Squill contains natural heart compounds (cardiac glycosides) that work a lot like digoxin. Quinine is known to slow how fast the body clears digoxin out of your system, and the concern is that it could do the same to squill's heart compounds, letting them build up.

If that happens, you could see signs of glycoside toxicity, things like nausea, an off heart rhythm, or feeling unusually dizzy or weak. I'll be honest with you though: this is a theoretical concern based on how these drugs behave, not strong real-world data. Still, squill is genuinely risky on its own, so please don't combine these without your doctor or pharmacist guiding you.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.

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

Squill Also Interacts With Other Medications

Squill has 1 major, 154 moderate known drug interactions in our database — the Quinine one above is one of them. If you take anything else, check it against the full list below.

Major 1 Moderate 154 No known interaction 2,675 (incl. Quinine)
Taking anything else?

Check Another of Your Medications Against Squill

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

From our Q&A

Questions About Squill or Quinine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Squill or Quinine, 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 Quinine

This page covers Squill only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Quinine page lists 175 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Cinchona (major), Foxglove (major), Grapefruit (major) and Lily-of-the-valley (major).

By severity: 9 major · 125 moderate · 41 minor.

From our pharmacist’s overview on the Quinine page

“Quinine (Qualaquin) earns a genuine pause before you add any supplement, because nine of its 175 interacting ingredients are rated major, and two are as everyday as grapefruit and St. John's wort.”

Reviewed by 2 · Jul 18, 2026

Open the Quinine interaction page

One more smart check

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

We hold 2 real supplement products containing Squill, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Squill. Your product may carry other ingredients that interact with Quinine too, on top of Squill — 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 Squill and Quinine 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 Squill
Top half

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

29 days ago today
Medication Quinine
Steady interest

#1,507 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 Squill

What is Squill?

Squill
  • Cough and chest congestion
  • Fluid retention (diuretic)
  • Heart conditions (traditional 'cardiac tonic')
  • Hair loss (topical use)
  • Rodenticide (red squill, non-medicinal)

Squill is a bulb plant that contains potent cardiac glycosides, which can affect the heart much like the drug digoxin. While it has a long history of use as a cough remedy and heart tonic, it can be dangerously toxic and there is little solid evidence for its modern use, so we do not recommend taking it without close medical supervision.

Read the full Squill monograph & all interactions
Medication

About Quinine

What Is Quinine Used For?

Brand name: Qualaquin

Quinine sulfate capsules (brands Qualaquin and Quinine Sulfate) are approved to treat uncomplicated Plasmodium falciparum malaria in adults. This includes strains of malaria that have become resistant to chloroquine.

Quinine sulfate capsules are not approved for severe or complicated malaria, for preventing malaria, or for treating or preventing nocturnal leg cramps. Using them for leg cramps carries serious risks that outweigh any potential benefit.

See full Quinine drug information
Keep checking

Other Drugs & Squill

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

1Major
154Moderate
0Minor
2,674No known interaction
1 Major 154 Moderate 2,674 No interaction
Major

1 interaction

Moderate

154 interactions

Showing 60 of 154 moderate interactions — see all 154 on the Squill page.

No interaction 2,674 drugs checked — show the list

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

Showing the 60 most looked-up of 2,674 medications checked with no known interaction — see the full Squill list.

See the full Squill interactions page
See every supplement checked against Quinine, 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
Squill monograph › Uses, safety, and every drug interaction in one place Quinine supplement interactions › Every supplement checked against Quinine, ranked by severity Quinine 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 Squill and Quinine Together: Common Questions

Can you take Squill with Quinine?
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 Squill and Quinine 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 Quinine and Squill?

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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.