Drug & supplement interaction

Feverfew + Diazepam

Diazepam brand names: Valium, Valium injection, Diastat AcuDial, Valtoco.

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

Diazepam falls into 4 drug categories that Feverfew can interact with; the most serious is rated moderate. Theoretically, feverfew might increase levels of drugs metabolized by CYP2C19.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions4
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Feverfew and Diazepam

These two interact in 4 distinct ways. Each one is explained separately below.

Why Are There 4 Interactions?

Feverfew interacts with whole categories of medication. Diazepam falls into 4 of those categories, so it can interact with Feverfew in 4 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 4

Why this applies to Diazepam

Diazepam falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Feverfew interacts with.

Theoretically, feverfew might increase levels of drugs metabolized by CYP2C19.
Laboratory research shows that feverfew might inhibit CYP2C19. So far, this interaction has not been reported in humans.
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 gist: your body uses a liver enzyme called CYP2C19 to help break down diazepam (Valium). Lab studies hint that feverfew might slow that enzyme down a bit. If that happened, diazepam could clear out more slowly and build up in your system, which in theory could leave you feeling extra drowsy, dizzy, foggy, or unsteady on your feet.

The good news is that this is only a theoretical concern. It has shown up in test-tube research, not in real people, so I wouldn't lose sleep over it. Still, since diazepam already makes plenty of folks sleepy, it's worth a quick chat with your pharmacist or doctor before adding feverfew, especially if you notice more grogginess than usual.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

2 of 4

Diazepam also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.

Theoretically, feverfew might increase levels of drugs metabolized by CYP1A2.
Laboratory research shows that feverfew might inhibit CYP1A2. So far, this interaction has not been reported in humans.
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 gist for diazepam (Valium). Feverfew may, at least in a test tube, slow down a liver enzyme called CYP1A2, which is one of the helpers your body uses to clear certain medicines. If that enzyme runs slower, a drug like diazepam could linger a bit longer and build up, which in theory might mean more drowsiness, dizziness, grogginess, or feeling unsteady on your feet.

The reassuring part: this is based only on lab research, not on anything seen in real people, so it's very much a theoretical concern. Diazepam isn't a prodrug, so it doesn't flip the other way. Still, since both can make you sleepy, it's worth a quick chat with your pharmacist or doctor before pairing them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

3 of 4

Diazepam also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, feverfew might increase levels of drugs metabolized by CYP2C9.
Laboratory research shows that feverfew might inhibit CYP2C9. So far, this interaction has not been reported in humans.
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 gist with feverfew and diazepam (Valium). Your liver uses an enzyme called CYP2C9 to help break down diazepam. Lab studies hint that feverfew might slow that enzyme down a bit. If that happened in real life, diazepam could clear out of your body a little slower and build up, which might make its effects stronger. With this drug that could mean extra drowsiness, dizziness, feeling foggy, or being less steady on your feet.

The big thing to know: this is theoretical. It comes from test-tube and animal research, and it has never actually been reported in people. So I wouldn't lose sleep over it. Still, if you take diazepam regularly and want to try feverfew, run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

4 of 4

Diazepam also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, feverfew might increase levels of drugs metabolized by CYP3A4.
Laboratory research shows that feverfew might inhibit CYP3A4. So far, this interaction has not been reported in humans.
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

Your body partly relies on a liver enzyme called CYP3A4 to break down diazepam (Valium) and clear it out. In test-tube studies, feverfew appears to slow that same enzyme down. If that happened in real life, diazepam could clear more slowly and build up a bit, which might make its calming effects stronger than expected. Think more drowsiness, grogginess, dizziness, or feeling unsteady on your feet.

Here is the reassuring part: this is only a theoretical concern from lab work, and it has never actually been reported in people. So it is something to be aware of, not panic over. Still, before pairing feverfew with your diazepam, please check with your pharmacist or doctor, especially if you already notice sedation.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
  2. Sil'vestrov VP, Kinitin AV, and Chesnokova, IV. [Immunological and metabolic disorders and the means for their correction in patients with chronic bronchitis]. Ter.Arkh. 1991;63:7-11.

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

Feverfew Also Interacts With Other Medications

Feverfew has 928 moderate known drug interactions in our database — the Diazepam one above is among them. If you take anything else, check it against the full list below.

Moderate 928 No known interaction 1,902 (incl. Diazepam)
Taking anything else?

Check Another of Your Medications Against Feverfew

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

From our Q&A

Questions About Feverfew or Diazepam

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Feverfew or Diazepam, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Diazepam

This page covers Feverfew only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Diazepam page lists 244 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 Grapefruit (major).

By severity: 9 major · 191 moderate · 44 minor.

Open the Diazepam interaction page

One more smart check

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

We hold 520 real supplement products containing Feverfew, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Feverfew. Your product may carry other ingredients that interact with Diazepam too, on top of Feverfew — 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 Feverfew and Diazepam 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 Feverfew
Top 25%

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

29 days ago today
Medication Diazepam
Top 5%

#128 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 Feverfew

What is Feverfew?

Feverfew
  • Migraine prevention
  • Headache
  • Fever (traditional)
  • Arthritis and joint pain
  • Menstrual discomfort

Feverfew is a daisy-family herb best known for migraine prevention, where some studies suggest it may modestly lower how often migraines occur, though the evidence is mixed. It is generally well tolerated for short-term use in most adults but should be avoided during pregnancy and breastfeeding and by people allergic to ragweed and related plants. Talk to your pharmacist or doctor before starting it.

Read the full Feverfew monograph & all interactions
Medication

About Diazepam

What Is Diazepam Used For?

Brand names: Valium, Valium injection, Diastat AcuDial, Valtoco

  • Diazepam is used to relieve anxiety and to control agitation caused by alcohol withdrawal. It is also used along with other medications to control muscle spasms and spasticity caused by certain neurological disorders such as cerebral palsy (condition that causes difficulty with movement and balance), paraplegia (inability to move parts of the body), athetosis (abnormal muscle contractions), and stiff-man syndrome (a rare disorder with muscle rigidity and stiffness). Diazepam is also used along with other medications to control seizures. Diazepam is in a class of medications called benzodiazepines. It works by calming abnormal overactivity in the brain.

See full Diazepam drug information
Keep checking

Other Drugs & Feverfew

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

0Major
928Moderate
0Minor
1,901No known interaction
928 Moderate 1,901 No interaction
Moderate

928 interactions

Showing 60 of 928 moderate interactions — see all 928 on the Feverfew page.

No interaction 1,901 drugs checked — show the list

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

Showing the 60 most looked-up of 1,901 medications checked with no known interaction — see the full Feverfew list.

See the full Feverfew interactions page
See every supplement checked against Diazepam, 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
Feverfew monograph › Uses, safety, and every drug interaction in one place Diazepam supplement interactions › Every supplement checked against Diazepam, ranked by severity Diazepam drug information › The full plain-English guide to this medication 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 Feverfew and Diazepam Together: Common Questions

Can you take Feverfew with Diazepam?
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.
Why are there 4 interactions listed for Feverfew and Diazepam?
Diazepam belongs to more than one drug category, and Feverfew interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Feverfew and Diazepam 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 Diazepam and Feverfew?

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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.