Drug & supplement interaction

Sage + Mephenytoin

Mephenytoin brand name: Mesantoin.

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

Mephenytoin falls into 3 drug categories that Sage can interact with; the most serious is rated moderate. Theoretically, taking sage might increase the sedative and adverse effects of CNS depressants.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Sage and Mephenytoin

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Sage interacts with whole categories of medication. Mephenytoin falls into 3 of those categories, so it can interact with Sage in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CNS DEPRESSANTS

1 of 3

Why this applies to Mephenytoin

Mephenytoin falls under CNS DEPRESSANTS — the group Sage interacts with.

Theoretically, taking sage might increase the sedative and adverse effects of CNS depressants.
Some constituents of sage have CNS depressant activity.
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

Mephenytoin (Mesantoin) is an older seizure medicine that can already make you feel drowsy or foggy. The concern here is simple: certain compounds in sage may have a mild calming or sedative effect of their own. When you stack that on top of a medicine that already slows the brain down, the tiredness, dizziness, or trouble concentrating could add up a bit more than usual.

I want to be honest about the strength of this one. It is theoretical, based on lab work rather than real patients, so it may not amount to much in everyday life. Cooking with sage is very unlikely to matter. Concentrated extracts or sage oil are where I would be more cautious. Before adding a sage supplement, check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Perry NS, Bollen C, Perry EK, Ballard C. Salvia for dementia therapy: review of pharmacological activity and pilot tolerability clinical trial. Pharmacol Biochem Behav 2003;75:651-9.. PubMed
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

2 of 3

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

Theoretically, sage might increase the levels and clinical effects of drugs metabolized by CYP2C9.
In vitro evidence suggests that aqueous extracts of sage can 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 for Mephenytoin (Mesantoin), an older seizure medicine. Your liver uses an enzyme called CYP2C9 to help break this drug down. Lab studies hint that water-based sage extracts can slow that same enzyme. If that slowdown happened in your body, mephenytoin could clear out more slowly and build up, which might mean more side effects like drowsiness, dizziness, unsteadiness, or confusion.

I want to be honest about the strength of this, though. So far this is only seen in test-tube research, never reported in real people, so it's mostly theoretical. Everyday cooking amounts of sage are very unlikely to cause trouble. Concentrated sage capsules or oil are where I'd be more cautious. Just check with your pharmacist or doctor before adding a sage supplement.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Foster BC, Vandenhoek S, Hana J, et al. In vitro inhibition of human cytochrome P450-mediated metabolism of marker substrates by natural products. Phytomedicine 2003;10:334-42.. PubMed
Moderate

ANTICONVULSANTS

3 of 3

Mephenytoin also falls under ANTICONVULSANTS.

Theoretically, sage might interfere with the clinical effects of anticonvulsant drugs.
Some species of sage can cause convulsions when consumed in large quantities.
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

Mephenytoin (Mesantoin) is an older seizure medicine that works by calming overactive electrical signals in the brain. The concern here is mostly theoretical: certain sage species, especially concentrated extracts and the essential oil, contain thujone, a compound that in large amounts can actually lower the seizure threshold and trigger convulsions. That could work against what your medication is trying to do, making seizures harder to control.

To be clear, this worry comes from lab and animal data, not strong human studies, and normal cooking amounts of sage are very unlikely to cause a problem. The caution applies to high-dose sage supplements or sage oil. Since seizure control is too important to gamble with, please check with your pharmacist or doctor before adding any concentrated sage product.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Perry NB, Anderson RE, Brennan NJ, et al. Essential oils from dalmatian sage (Salvia officinalis l.): variations among individuals, plant parts, seasons, and sites. J Agric Food Chem 1999;47:2048-54..

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

Sage Also Interacts With Other Medications

Sage has 1,295 moderate known drug interactions in our database — the Mephenytoin one above is among them. If you take anything else, check it against the full list below.

Moderate 1,295 No known interaction 1,535 (incl. Mephenytoin)
Taking anything else?

Check Another of Your Medications Against Sage

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

Everything else you take

See Every Supplement That Interacts With Mephenytoin

This page covers Sage only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mephenytoin page lists 215 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 Kava (major).

By severity: 9 major · 178 moderate · 28 minor.

From our pharmacist’s overview on the Mephenytoin page

“Anyone taking mephenytoin (Mesantoin) for seizures should read this page with genuine care rather than as background noise. The biggest cluster of interactions piles sedation on top of a drug that already slows the nervous system, and alcohol, whether beer or wine, sits at the serious end of that group.”

Reviewed by 2 · Jul 18, 2026

Open the Mephenytoin interaction page

One more smart check

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

We hold 718 real supplement products containing Sage, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Sage. Your product may carry other ingredients that interact with Mephenytoin too, on top of Sage — 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 Sage and Mephenytoin 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 Sage
Top 25%

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

29 days ago today
Medication Mephenytoin
Steady interest

#2,134 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 Sage

What is Sage?

Sage
  • Sore throat and mouth irritation
  • Digestive upset
  • Excessive sweating
  • Memory and thinking
  • Menopause symptoms (hot flashes)
  • General antioxidant support

Sage is a common kitchen herb that is generally safe in food amounts and is traditionally used for sore throats, digestion, sweating, and memory. Some early research is encouraging for sore throat and menopausal hot flashes, but most uses are not well proven. Concentrated extracts and the essential oil should be used carefully because high doses contain a compound called thujone, which can be harmful.

Read the full Sage monograph & all interactions
Keep checking

Other Drugs & Sage

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

0Major
1,295Moderate
0Minor
1,534No known interaction
1,295 Moderate 1,534 No interaction
Moderate

1,295 interactions

Showing 60 of 1,295 moderate interactions — see all 1,295 on the Sage page.

No interaction 1,534 drugs checked — show the list

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

Showing the 60 most looked-up of 1,534 medications checked with no known interaction — see the full Sage list.

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

Can you take Sage with Mephenytoin?
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 3 interactions listed for Sage and Mephenytoin?
Mephenytoin belongs to more than one drug category, and Sage 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 Sage and Mephenytoin 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.