Drug & supplement interaction

Spearmint + Fosphenytoin

Fosphenytoin brand name: Cerebyx.

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

Fosphenytoin falls into 2 drug categories that Spearmint can interact with; the most serious is rated moderate. Theoretically, spearmint might alter the sedative effects of CNS depressants.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Spearmint and Fosphenytoin

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Spearmint interacts with whole categories of medication. Fosphenytoin falls into 2 of those categories, so it can interact with Spearmint in 2 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 2

Why this applies to Fosphenytoin

Fosphenytoin falls under CNS DEPRESSANTS — the group Spearmint interacts with.

Theoretically, spearmint might alter the sedative effects of CNS depressants.
Animal research suggests that (-)-carvone, a major constituent of spearmint, has sedative effects. However, in humans, chewing spearmint-flavored gum induced arousal effects.
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 honest version when it comes to spearmint and your fosphenytoin (Cerebyx): this is a very theoretical concern, not something backed by solid human studies. The idea is that one compound in spearmint, called carvone, looked mildly sedating in animal research. Since fosphenytoin can already cause drowsiness, dizziness, and unsteadiness, the worry is that the two together might pile on a little extra sleepiness. Interestingly, in people, spearmint gum actually seemed to make folks more alert, so the picture is murky.

For everyday cooking and a cup of mint tea, I wouldn't lose sleep over this. Concentrated spearmint supplements are a different story, so it's worth running those by your pharmacist or doctor before starting, especially since seizure meds deserve extra care.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. de Sousa, D. P., Farias Nobrega, F. F., and de Almeida, R. N. Influence of the chirality of (R)-(-)- and (S)-(+)-carvone in the central nervous system: a comparative study. Chirality 5-5-2007;19(4):264-268.
  2. Masumoto, Y., Morinushi, T., Kawasaki, H., Ogura, T., and Takigawa, M. Effects of three principal constituents in chewing gum on electroencephalographic activity. Psychiatry Clin.Neurosci. 1999;53(1):17-23. PubMed
  3. Goncalves, J. C., Oliveira, Fde S., Benedito, R. B., de Sousa, D. P., de Almeida, R. N., and de Araujo, D. A. Antinociceptive activity of (-)-carvone: evidence of association with decreased peripheral nerve excitability. Biol Pharm Bull. 2008;31(5):1017- PubMed
Moderate

HEPATOTOXIC DRUGS

2 of 2

Fosphenytoin also falls under HEPATOTOXIC DRUGS.

Theoretically, high doses of spearmint might increase the risk of liver damage when taken with hepatotoxic drugs.
Animal research suggests that drinking spearmint tea for 30 days can increase markers of liver damage, including aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and cause liver degeneration and necrosis, in a dose-dependent manner. This effect 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 spearmint and fosphenytoin (Cerebyx). This isn't about spearmint changing how your seizure medicine works. The concern is purely about the liver. Fosphenytoin can put some stress on the liver, and the worry is that piling concentrated spearmint on top might add to that load.

Honestly, this is a very theoretical caution. It comes from animal studies where large amounts of spearmint tea over 30 days nudged up liver enzymes (AST and ALT). Nothing like this has been shown in people. A little spearmint in food or an occasional cup of tea is very unlikely to matter. If you're thinking about high-dose spearmint supplements, just run it by your doctor or pharmacist first, since they may already be watching your liver labs.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Akdogan M, Ozguner M, Aydin G, Gokalp O. Investigation of biochemical and histopathological effects of Mentha piperita Labiatae and Mentha spicata Labiatae on liver tissue in rats. Hum Exp Toxicol 2004;23:21-8.

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

Spearmint Also Interacts With Other Medications

Spearmint has 578 moderate known drug interactions in our database — the Fosphenytoin one above is among them. If you take anything else, check it against the full list below.

Moderate 578 No known interaction 2,252 (incl. Fosphenytoin)
Taking anything else?

Check Another of Your Medications Against Spearmint

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

Everything else you take

See Every Supplement That Interacts With Fosphenytoin

This page covers Spearmint only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin page lists 205 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 · 172 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin page

“St. John's wort is the entry I would flag first with fosphenytoin (Cerebyx).”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin interaction page

One more smart check

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

We hold 408 real supplement products containing Spearmint, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Spearmint. Your product may carry other ingredients that interact with Fosphenytoin too, on top of Spearmint — 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 Spearmint and Fosphenytoin 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 Spearmint
Top 25%

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

29 days ago today
Medication Fosphenytoin
Steady interest

#2,094 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 Spearmint

What is Spearmint?

Spearmint
  • Digestive upset and indigestion
  • Nausea
  • Hormonal acne and unwanted hair (PCOS-related)
  • Memory and focus
  • Mild stress and anxiety
  • Joint discomfort

Spearmint is a common culinary mint that is generally safe in food and tea amounts. Early research suggests possible benefits for digestion, mild hormone-related issues (such as excess facial hair in women), and memory, but the evidence is still limited. Talk to your pharmacist or doctor before using concentrated supplements, especially if you are pregnant or have a health condition.

Read the full Spearmint monograph & all interactions
Medication

About Fosphenytoin Injection

What Is Fosphenytoin Injection Used For?

Brand name: Cerebyx

Fosphenytoin injection is used to treat generalized tonic-clonic status epilepticus (a prolonged, life-threatening seizure emergency) and to prevent or treat seizures that occur during or after brain surgery. It is given by intravenous (IV) or intramuscular (IM) injection in a hospital or clinical setting.

It can also be used short-term as a substitute for oral phenytoin when a patient cannot take medicine by mouth. This use is temporary — as soon as oral phenytoin is possible again, it should replace the injection.

See full Fosphenytoin Injection drug information
Keep checking

Other Drugs & Spearmint

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

0Major
578Moderate
0Minor
2,251No known interaction
578 Moderate 2,251 No interaction
Moderate

578 interactions

Showing 60 of 578 moderate interactions — see all 578 on the Spearmint page.

No interaction 2,251 drugs checked — show the list

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

Showing the 60 most looked-up of 2,251 medications checked with no known interaction — see the full Spearmint list.

See the full Spearmint interactions page
See every supplement checked against Fosphenytoin, 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
Spearmint monograph › Uses, safety, and every drug interaction in one place Fosphenytoin supplement interactions › Every supplement checked against Fosphenytoin, ranked by severity Fosphenytoin Injection 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 Spearmint and Fosphenytoin Together: Common Questions

Can you take Spearmint with Fosphenytoin?
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 2 interactions listed for Spearmint and Fosphenytoin?
Fosphenytoin belongs to more than one drug category, and Spearmint 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 Spearmint and Fosphenytoin 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 Fosphenytoin and Spearmint?

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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.