Drug & supplement interaction

Groundsel + Hyoscyamine, Phenobarbital

Hyoscyamine, Phenobarbital brand names: Levsin Pb, Levsinex Pb Timecaps.

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

Groundsel has a moderate interaction with Hyoscyamine, Phenobarbital. Theoretically, taking CYP3A4 inducers with groundsel might increase the risk of pyrrolizidine alkaloid toxicity, such as hepatotoxicity.

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

Groundsel and Hyoscyamine, Phenobarbital

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INDUCERS

Why this applies to Hyoscyamine, Phenobarbital

Hyoscyamine, Phenobarbital falls under CYTOCHROME P450 3A4 (CYP3A4) INDUCERS — the group Groundsel interacts with.

Theoretically, taking CYP3A4 inducers with groundsel might increase the risk of pyrrolizidine alkaloid toxicity, such as hepatotoxicity.
Pyrrolizidine alkaloids, constituents of groundsel, are converted to toxic metabolites by CYP3A4.
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, a big-picture note: I really wouldn't recommend taking groundsel at all. It contains pyrrolizidine alkaloids that can seriously damage your liver, and there's no good proof it helps anything.

Here's the specific concern with your Levsin PB (hyoscyamine and phenobarbital). The phenobarbital part is a known inducer of a liver enzyme called CYP3A4, meaning it speeds that enzyme up. Unfortunately, that same enzyme turns groundsel's alkaloids into their toxic forms. So in theory, the phenobarbital could ramp up the production of those harmful byproducts and raise the risk of liver injury. Be honest, this is based only on lab and animal data, not real patient cases, so it's a theoretical worry rather than a proven one. Still, given how dangerous groundsel is on its own, please skip it and check with your pharmacist or doctor.

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

Groundsel Also Interacts With Other Medications

Groundsel has 86 moderate known drug interactions in our database — the Hyoscyamine, Phenobarbital 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. Hyoscyamine, Phenobarbital)
Taking anything else?

Check Another of Your Medications Against Groundsel

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

Everything else you take

See Every Supplement That Interacts With Hyoscyamine, Phenobarbital

This page covers Groundsel only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hyoscyamine, Phenobarbital page lists 164 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Henbane (major).

By severity: 10 major · 134 moderate · 20 minor.

From our pharmacist’s overview on the Hyoscyamine, Phenobarbital page

“The person taking Levsin PB (hyoscyamine with phenobarbital) for gut spasms is often the same person browsing calming herbs and sleep aids, and with this medicine that habit calls for real vigilance. Ten of the 164 supplements on record rate major, and the largest group, 78 ingredients, shares one danger.”

Reviewed by 2 · Jul 18, 2026

Open the Hyoscyamine, Phenobarbital interaction page

How much people look this up

Where Groundsel and Hyoscyamine, Phenobarbital 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 Groundsel
Top half

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

29 days ago today
Medication Hyoscyamine, Phenobarbital
Top 10%

#188 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 Groundsel

What is Groundsel?

  • Menstrual complaints
  • Digestive upset
  • Minor wounds (topical)
  • Sore gums or mouth
  • Mild aches

Groundsel is a common weed traditionally used as a folk remedy, but it contains pyrrolizidine alkaloids that can cause serious liver damage. There is no reliable evidence that it works for any condition, and most health authorities consider it unsafe to take internally. We do not recommend using it.

Read the full Groundsel monograph & all interactions
Keep checking

Other Drugs & Groundsel

Browse every other medication we’ve checked against Groundsel — 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 Groundsel page.

No interaction 2,743 drugs checked — show the list

We also checked Groundsel 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 Groundsel list.

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

Can you take Groundsel with Hyoscyamine, Phenobarbital?
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 Groundsel and Hyoscyamine, Phenobarbital 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.