Drug & supplement interaction

Swamp Milkweed + Quinine Sulfate

Quinine Sulfate brand names: Quinamm, Quinine Sulfate.

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

Swamp Milkweed has a major interaction with Quinine Sulfate. Theoretically, quinine might increase the risk of toxicity from cardioactive steroids in swamp milkweed.

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

Swamp Milkweed and Quinine Sulfate

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

Major

QUININE

Theoretically, quinine might increase the risk of toxicity from cardioactive steroids in swamp milkweed.
Swamp milkweed contains cardioactive steroids known as cardenolides that may have digitalis-like activity. Quinine may reduce the clearance of oral digoxin. Theoretically, concomitant use of quinine might reduce the clearance of cardenolides found in swamp milkweed and increase the risk of adverse effects.
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 for swamp milkweed and quinine. Swamp milkweed's sap carries natural compounds called cardenolides that act a bit like the old heart drug digitalis. Quinine can slow how your body clears those digitalis-like substances, so they may linger and build up. That can nudge your heart rhythm in the wrong direction, causing things like a pounding or irregular heartbeat, nausea, dizziness, or vision changes. Quinine itself can already affect heart rhythm, so stacking the two is a real concern.

I'll be honest: this is a theoretical interaction based on how these compounds behave, not on solid human studies. Even so, swamp milkweed is genuinely toxic and isn't a safe supplement to take on your own. Please don't combine them without first checking with your doctor or pharmacist.

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.
  2. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 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

Swamp Milkweed Also Interacts With Other Medications

Swamp Milkweed has 2 major, 153 moderate known drug interactions in our database — the Quinine Sulfate one above is one of them. If you take anything else, check it against the full list below.

Major 2 Moderate 153 No known interaction 2,675 (incl. Quinine Sulfate)
Taking anything else?

Check Another of Your Medications Against Swamp Milkweed

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

Everything else you take

See Every Supplement That Interacts With Quinine Sulfate

This page covers Swamp Milkweed only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Quinine Sulfate 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).

Open the Quinine Sulfate interaction page

How much people look this up

Where Swamp Milkweed and Quinine Sulfate 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 Swamp Milkweed
Top half

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

29 days ago today
Medication Quinine Sulfate
Steady interest

#2,652 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 Swamp Milkweed

What is Swamp Milkweed?

  • Traditional digestive remedy
  • Diuretic (increasing urine)
  • Cough and respiratory complaints
  • Worm or parasite remedy (folk use)
  • Pollinator/garden plant rather than medicine

Swamp Milkweed is a native North American wetland plant best known today as a butterfly and pollinator garden plant, not a proven medicine. It contains toxic milky sap with cardiac glycoside-like compounds, and there is very little reliable human research to support any health use. Because of its potential toxicity, it should not be used as a supplement without professional guidance.

Read the full Swamp Milkweed monograph & all interactions
Keep checking

Other Drugs & Swamp Milkweed

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

2Major
153Moderate
0Minor
2,674No known interaction
2 Major 153 Moderate 2,674 No interaction
Major

2 interactions

Moderate

153 interactions

Showing 60 of 153 moderate interactions — see all 153 on the Swamp Milkweed page.

No interaction 2,674 drugs checked — show the list

We also checked Swamp Milkweed 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 Swamp Milkweed list.

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

Can you take Swamp Milkweed with Quinine Sulfate?
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 Swamp Milkweed and Quinine Sulfate 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

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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.