Drug & supplement interaction

Sage + Phenobarbital, Phenytoin

Phenobarbital, Phenytoin brand name: Dilantin with PB.

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

Phenobarbital, Phenytoin falls into 4 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
Interactions4
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Sage and Phenobarbital, Phenytoin

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

Why Are There 4 Interactions?

Sage interacts with whole categories of medication. Phenobarbital, Phenytoin falls into 4 of those categories, so it can interact with Sage in 4 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 4

Why this applies to Phenobarbital, Phenytoin

Phenobarbital, Phenytoin 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

Here's the simple version: this combo pairs an herb that may have mild calming activity with phenobarbital and phenytoin, which already work by slowing down the nervous system. The thought is that some compounds in sage could add to that sedating effect. With these medicines, that might show up as extra drowsiness, dizziness, grogginess, or feeling unsteady on your feet.

I want to be honest about the strength of this concern. It is theoretical, based only on lab and animal findings, not on real cases in people. A bit of sage seasoning on your dinner is very unlikely to cause any trouble. Concentrated sage extracts or sage essential oil are a different story and deserve more caution. Phenytoin in particular has a narrow safety window, so before adding any sage supplement, just run it by 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 2C19 (CYP2C19) SUBSTRATES

2 of 4

Phenobarbital, Phenytoin also falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES.

Theoretically, sage might increase the levels and clinical effects of drugs metabolized by CYP2C19.
In vitro evidence suggests that aqueous extracts of sage can 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 for this combo. Your body uses a liver enzyme called CYP2C19 to help clear phenytoin (and to a lesser extent phenobarbital). In lab dish studies, water-based sage extracts seemed to slow that enzyme down a bit. If that happened in a real person, these seizure medicines could build up slightly, which for phenytoin might mean things like dizziness, unsteady walking, slurred speech, blurry or jumpy vision, or feeling extra drowsy.

The important part: this is only a theoretical, test-tube finding and has never actually been reported in people. Phenytoin is a tricky drug where small changes can matter, so I'd still mention any concentrated sage supplements or sage oil to your pharmacist. Sprinkling sage on dinner is very unlikely to be a problem.

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

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

3 of 4

Phenobarbital, Phenytoin 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 quick version with this combo. Your body clears phenytoin partly through a liver enzyme called CYP2C9. Lab studies suggest sage may slow that enzyme down a bit, which could let phenytoin build up in your blood. Phenytoin is a tricky drug because the safe window is narrow, so even a small rise can tip you into side effects like dizziness, unsteady walking, slurred speech, double vision, or unusual drowsiness.

That said, this is only test-tube evidence and hasn't actually been seen in people, so I wouldn't panic. Cooking with sage is very unlikely to matter. Concentrated extracts or sage oil are the bigger question mark. Please don't change anything on your own, just check with your pharmacist or doctor first.

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

4 of 4

Phenobarbital, Phenytoin 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

Here's the situation with sage and your seizure medicines. Both phenytoin (Dilantin) and phenobarbital work to calm down the electrical activity in your brain that triggers seizures. The concern is that certain sage species, especially concentrated extracts or the essential oil, contain a compound called thujone that can actually lower the seizure threshold. In plain terms, sage could theoretically work against your medication and make a seizure more likely to break through.

I want to be honest about how solid this is: this caution comes from lab and animal studies, not from people, so it's more of a theoretical worry than a proven problem. Sage used as a normal cooking spice is very unlikely to cause trouble. The real caution is with high-dose supplements or sage oil. Before adding any sage product, please check with your pharmacist or neurologist first.

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 Phenobarbital, Phenytoin 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. Phenobarbital, Phenytoin)
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 Phenobarbital, Phenytoin

This page covers Sage only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenobarbital, Phenytoin page lists 229 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 · 192 moderate · 28 minor.

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

“If your seizure medicine is the phenobarbital and phenytoin combination (Dilantin with PB), read this list carefully before you add any supplement. Nine of the 229 entries rate major, and most of the risk runs through two channels.”

Reviewed by 2 · Jul 18, 2026

Open the Phenobarbital, Phenytoin 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 Phenobarbital, Phenytoin 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 Phenobarbital, Phenytoin 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%

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

29 days ago today
Medication Phenobarbital, Phenytoin
Steady interest

#2,102 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 Phenobarbital, Phenytoin, 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 Phenobarbital, Phenytoin supplement interactions › Every supplement checked against Phenobarbital, Phenytoin, 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 Phenobarbital, Phenytoin Together: Common Questions

Can you take Sage with Phenobarbital, Phenytoin?
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 Sage and Phenobarbital, Phenytoin?
Phenobarbital, Phenytoin 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 Phenobarbital, Phenytoin 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.