Drug & supplement interaction

Spearmint + Fosphenytoin Sodium

Fosphenytoin Sodium brand name: Sesquient.

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

Fosphenytoin Sodium 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 Sodium

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 Sodium 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 Sodium

Fosphenytoin Sodium 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 picture: fosphenytoin (Sesquient) is a hospital-administered medicine that the body converts into phenytoin to control seizures. The only concern raised here is very mild and very theoretical. One compound in spearmint, called carvone, made animals a bit drowsy in lab studies, so on paper spearmint could add to the sleepy, sedating side of medicines like this one. Interestingly, in real people, spearmint gum actually seemed to wake folks up, not calm them down.

In practice, the small amounts of spearmint in food, tea, or gum are very unlikely to change how fosphenytoin works or make you noticeably more groggy. Since this drug needs careful dosing, just mention any concentrated spearmint supplements to your care team before using them.

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 Sodium 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 simple version. Fosphenytoin (Sesquient) is a seizure medicine that your body converts to phenytoin, and like many seizure drugs it can be tough on the liver in some people. Spearmint, in very high concentrated doses, has been linked to liver stress too, but only in animal studies. So the theory is that stacking the two could add to liver strain.

I want to be honest with you: this is theoretical, based on lab and animal data, and it has not been seen in humans. The spearmint in tea or as a seasoning is very unlikely to matter. Concentrated spearmint supplements are the real question. Since fosphenytoin already needs liver monitoring, just check with your pharmacist or doctor before adding any spearmint supplement.

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 Sodium 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 Sodium)
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 Sodium

This page covers Spearmint only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin Sodium page lists 212 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 · 179 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin Sodium page

“Fosphenytoin sodium (Sesquient) converts to phenytoin in the body, and phenytoin is unforgiving about blood levels. A little too low invites seizures, a little too high brings toxicity.”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin Sodium 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 Sodium 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 Sodium 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%

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

29 days ago today
Medication Fosphenytoin Sodium
Top 10%

#144 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
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 Sodium, 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 Sodium supplement interactions › Every supplement checked against Fosphenytoin Sodium, 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 Spearmint and Fosphenytoin Sodium Together: Common Questions

Can you take Spearmint with Fosphenytoin Sodium?
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 Sodium?
Fosphenytoin Sodium 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 Sodium 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.