Drug & supplement interaction

Fever Bark + Enflurane

Enflurane brand name: Ethrane.

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

Fever Bark has a major interaction with Enflurane. Theoretically, fever bark might increase the risk of cardiovascular instability with general anesthesia.

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

Fever Bark and Enflurane

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

Major

ANESTHESIA

Why this applies to Enflurane

Enflurane falls under ANESTHESIA — the group Fever Bark interacts with.

Theoretically, fever bark might increase the risk of cardiovascular instability with general anesthesia.
Reserpine, a constituent of fever bark, has been shown to increase the risk of cardiovascular instability in patients receiving general anesthesia. It is not known if this could occur with fever bark.
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

Enflurane (Ethrane) is an inhaled general anesthetic used to put you under during surgery. Fever bark contains reserpine-like alkaloids, and reserpine is known to deplete some of the body's natural chemicals that help keep blood pressure and heart rate steady. The concern here is that taking fever bark before going under anesthesia could make you more prone to cardiovascular instability, meaning swings in blood pressure (often a drop) or an unstable heart rate while you're being anesthetized.

I want to be honest about the evidence: this is largely theoretical and based on what reserpine does, not on solid studies of fever bark itself. Still, because it could be serious, please tell your surgeon and anesthesiologist about any fever bark use well before a planned surgery so they can plan safely. Don't start or stop anything on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sklar S, et al. Drug therapy screening system. Indianapolis, IN: First Data Bank 99.1-99. 2 eds.

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

Fever Bark Also Interacts With Other Medications

Fever Bark has 39 major, 674 moderate, 87 minor known drug interactions in our database — the Enflurane one above is one of them. If you take anything else, check it against the full list below.

Major 39 Moderate 674 Minor 87 No known interaction 2,030 (incl. Enflurane)
Taking anything else?

Check Another of Your Medications Against Fever Bark

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

Everything else you take

See Every Supplement That Interacts With Enflurane

This page covers Fever Bark only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Enflurane page lists 22 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Cannabis (moderate), Coffee Charcoal (moderate), Cowhage (moderate) and Datura Wrightii (moderate).

By severity: 2 major · 11 moderate · 9 minor.

From our pharmacist’s overview on the Enflurane page

“Enflurane (Ethrane) is an inhaled anesthetic used during surgery, and this list is one to treat with real caution, starting with its two major-rated interactions. Fever bark contains a compound linked to dangerous heart and blood pressure instability under general anesthesia, and activated charcoal can strip many drugs from the body, e…”

Reviewed by 2 · Jul 18, 2026

Open the Enflurane interaction page

How much people look this up

Where Fever Bark and Enflurane 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 Fever Bark
Steady interest

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

29 days ago today
Medication Enflurane
Steady interest

#2,640 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 Fever Bark

What is Fever Bark?

Fever Bark
  • Fever
  • Diarrhea
  • Malaria (traditional)
  • Digestive complaints
  • Bitter tonic

Fever bark is the bark of the Australian tree Alstonia constricta, used in traditional medicine for fever, diarrhea, and infections. There is very little reliable human research to support these uses, and the bark contains potent alkaloids that may cause serious side effects. It is best avoided unless used under direct medical supervision.

Read the full Fever Bark monograph & all interactions
Keep checking

Other Drugs & Fever Bark

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

39Major
674Moderate
87Minor
2,029No known interaction
39 Major 674 Moderate 87 Minor 2,029 No interaction
Major

39 interactions

Moderate

674 interactions

Showing 60 of 674 moderate interactions — see all 674 on the Fever Bark page.

Minor

87 interactions

Showing 60 of 87 minor interactions — see all 87 on the Fever Bark page.

No interaction 2,029 drugs checked — show the list

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

Showing the 60 most looked-up of 2,029 medications checked with no known interaction — see the full Fever Bark list.

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

Can you take Fever Bark with Enflurane?
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 Fever Bark and Enflurane 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 Enflurane and Fever Bark?

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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.