Drug & supplement interaction

Foxglove + Oxytetracycline

Oxytetracycline brand name: Terramycin.

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

Foxglove has a moderate interaction with Oxytetracycline. Theoretically, concomitant use of quinine increases the risk of cardiac glycoside toxicity.

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

Foxglove and Oxytetracycline

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

Moderate

TETRACYCLINE ANTIBIOTICS

Why this applies to Oxytetracycline

Oxytetracycline falls under TETRACYCLINE ANTIBIOTICS — the group Foxglove interacts with.

Theoretically, concomitant use of quinine increases the risk of cardiac glycoside toxicity.
Foxglove contains varied cardiac glycosides, including digoxin. Tetracycline can increase oral absorption of some cardiac glycosides.
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

First things first: foxglove is a poisonous plant, not a supplement you should ever take on its own. It naturally contains heart-acting compounds called cardiac glycosides, the same family as the prescription drug digoxin. That alone makes it dangerous.

Here's the theoretical concern with oxytetracycline (Terramycin). Some research suggests tetracycline antibiotics can change the gut bacteria that normally break down a portion of cardiac glycosides, which may let more of these heart compounds get absorbed. In plain terms, that could push the heart effects from foxglove higher, raising the risk of toxicity like nausea, vomiting, a slow or irregular heartbeat, and dizziness. Oxytetracycline is not a prodrug, so this isn't about activating it. This is theoretical, but given how toxic foxglove is, please don't combine them and check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.

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

Foxglove Also Interacts With Other Medications

Foxglove has 3 major, 129 moderate known drug interactions in our database — the Oxytetracycline one above is one of them. If you take anything else, check it against the full list below.

Major 3 Moderate 129 No known interaction 2,698 (incl. Oxytetracycline)
Taking anything else?

Check Another of Your Medications Against Foxglove

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

Everything else you take

See Every Supplement That Interacts With Oxytetracycline

This page covers Foxglove only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Oxytetracycline page lists 161 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Oleander (major) and Siberian Cocklebur (major).

By severity: 7 major · 134 moderate · 20 minor.

From our pharmacist’s overview on the Oxytetracycline page

“Calcium is the everyday supplement most likely to blunt oxytetracycline (Terramycin), a tetracycline antibiotic. It binds the drug in the gut, so take oral doses at least 2 hours before or 4 to 6 hours after any calcium product.”

Reviewed by 2 · Jul 18, 2026

Open the Oxytetracycline interaction page

One more smart check

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

We hold 1 real supplement products containing Foxglove, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Foxglove. Your product may carry other ingredients that interact with Oxytetracycline too, on top of Foxglove — 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 Foxglove and Oxytetracycline 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 Foxglove
Top half

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

29 days ago today
Medication Oxytetracycline
Steady interest

#2,665 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 Foxglove

What is Foxglove?

  • Heart failure (historical/medical use)
  • Irregular heartbeat (historical/medical use)
  • Fluid retention or 'dropsy' (historical use)
  • Ornamental garden plant

Foxglove is a beautiful but highly poisonous plant that contains powerful heart-affecting compounds called cardiac glycosides. It should never be used as a home remedy or supplement because even small amounts can cause life-threatening heart problems. The purified prescription drugs derived from it (like digoxin) are used only under close medical supervision.

Read the full Foxglove monograph & all interactions
Keep checking

Other Drugs & Foxglove

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

3Major
129Moderate
0Minor
2,697No known interaction
3 Major 129 Moderate 2,697 No interaction
Major

3 interactions

Moderate

129 interactions

Showing 60 of 129 moderate interactions — see all 129 on the Foxglove page.

No interaction 2,697 drugs checked — show the list

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

Showing the 60 most looked-up of 2,697 medications checked with no known interaction — see the full Foxglove list.

See the full Foxglove interactions page
See every supplement checked against Oxytetracycline, 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
Foxglove monograph › Uses, safety, and every drug interaction in one place Oxytetracycline supplement interactions › Every supplement checked against Oxytetracycline, 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 Foxglove and Oxytetracycline Together: Common Questions

Can you take Foxglove with Oxytetracycline?
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 Foxglove and Oxytetracycline 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 Oxytetracycline and Foxglove?

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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.