Drug & supplement interaction

Boneset + Fosphenytoin Sodium

Fosphenytoin Sodium brand name: Sesquient.

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

Boneset has a moderate interaction with Fosphenytoin Sodium. Boneset belongs to the genus Eupatorium, and many species of this genus contain hepatotoxic pyrrolizidine alkaloids (PAs).

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

Boneset and Fosphenytoin Sodium

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INDUCERS

Why this applies to Fosphenytoin Sodium

Fosphenytoin Sodium falls under CYTOCHROME P450 3A4 (CYP3A4) INDUCERS — the group Boneset interacts with.

Boneset belongs to the genus Eupatorium, and many species of this genus contain hepatotoxic pyrrolizidine alkaloids (PAs). Hepatotoxic PAs are substrates of cytochrome P450 3A4 (CYP3A4). Theoretically, drugs that induce CYP3A4 might increase the conversion of PAs to toxic metabolites. Some drugs that induce CYP3A4 include carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin), rifampin, rifabutin (Mycobutin), 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 key thing to understand about this pairing. Fosphenytoin (Sesquient) converts in your body to phenytoin, which is a known booster (inducer) of the CYP3A4 enzyme system. Boneset comes from a plant family that can contain pyrrolizidine alkaloids, compounds that the liver can turn into harmful byproducts using that same CYP3A4 pathway. So the worry isn't that boneset changes your seizure control. It's the reverse direction: by revving up CYP3A4, fosphenytoin could theoretically speed up the conversion of boneset's alkaloids into liver-toxic forms.

I'll be honest, this is a theoretical concern based on how these compounds behave, not on real patient studies. Still, both phenytoin and boneset can stress the liver on their own, so combining them isn't something I'd take lightly. Please run it by your doctor or pharmacist before using boneset.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46. PubMed
  2. Wang YP, Yan J, Fu PP, Chou MW. Human liver microsomal reduction of pyrrolizidine alkaloid N-oxides to form the corresponding carcinogenic parent alkaloid. Toxicol Lett 2005;155:411-20. PubMed

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

Boneset Also Interacts With Other Medications

Boneset has 86 moderate known drug interactions in our database — the Fosphenytoin Sodium one above is one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Fosphenytoin Sodium)
Taking anything else?

Check Another of Your Medications Against Boneset

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

Everything else you take

See Every Supplement That Interacts With Fosphenytoin Sodium

This page covers Boneset only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin Sodium page lists 212 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 14 major · 179 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin Sodium page

“Fosphenytoin sodium (Sesquient) converts to phenytoin in the body, and phenytoin is unforgiving about blood levels. A little too low invites seizures, a little too high brings toxicity.”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin Sodium interaction page

One more smart check

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

We hold 118 real supplement products containing Boneset, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Boneset. Your product may carry other ingredients that interact with Fosphenytoin Sodium too, on top of Boneset — 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 Boneset and Fosphenytoin Sodium 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 Boneset
Top half

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

29 days ago today
Medication Fosphenytoin Sodium
Steady interest

#2,295 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 Boneset

What is Boneset?

  • Colds and flu
  • Fever
  • Body aches
  • Congestion
  • Immune support

Boneset is a traditional North American herb long used in teas for fevers, colds, and flu, but modern human studies are very limited. It contains compounds (pyrrolizidine alkaloids) that may harm the liver, so it should be used cautiously and avoided during pregnancy and breastfeeding.

Read the full Boneset monograph & all interactions
Keep checking

Other Drugs & Boneset

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Boneset page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Boneset list.

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

Can you take Boneset with Fosphenytoin Sodium?
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 Boneset and Fosphenytoin Sodium 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

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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.