Drug & supplement interaction

Green Tea + 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 Green Tea can interact with; the most serious is rated moderate. Theoretically, concomitant use might have additive adverse hepatotoxic effects.

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

Green Tea and Fosphenytoin Sodium

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

Why Are There 2 Interactions?

Green Tea interacts with whole categories of medication. Fosphenytoin Sodium falls into 2 of those categories, so it can interact with Green Tea in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

HEPATOTOXIC DRUGS

1 of 2

Why this applies to Fosphenytoin Sodium

Fosphenytoin Sodium falls under HEPATOTOXIC DRUGS — the group Green Tea interacts with.

Theoretically, concomitant use might have additive adverse hepatotoxic effects.
Green tea extract supplements have been linked to several cases of hepatotoxicity and might have additive hepatotoxic effects with other drugs..
Severity Moderate Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for fosphenytoin (Sesquient). This isn't about green tea changing how the drug works in your brain. Instead, both fosphenytoin and concentrated green tea extract can, in rare cases, be hard on the liver. The worry is that stacking two liver stressors together might add up. To be clear, this is a theoretical concern based on a few scattered reports, not strong proof, so I wouldn't lose sleep over it.

Drinking a cup or two of green tea is very unlikely to matter. The real question is high-dose green tea extract pills. If you take those, watch for yellowing skin or eyes, dark urine, belly pain, or unusual tiredness, and loop in your doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Bonkovsky HL. Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Ann Intern Med 2006;144:68-71.
  2. Gloro R, Hourmand-Ollivier I, Mosquet B, et al. Fulminant hepatitis during self-medication with hydroalcoholic extract of green tea. Eur J Gastroenterol Hepatol 2005;17:1135-7. PubMed
  3. Jimenez-Saenz M, Martinez-Sanchez, MDC. Acute hepatitis associated with the use of green tea infusions. J Hepatol 2006;44:616-9. PubMed
  4. Javaid, A. and Bonkovsky, H. L. Hepatotoxicity due to extracts of Chinese green tea (Camellia sinensis): a growing concern. J Hepatol 2006;45(2):334-335. PubMed
  5. Martinez-Sierra, C., Rendon, Unceta P., and Martin, Herrera L. [Acute hepatitis after green tea ingestion]. Med Clin (Barc.) 6-17-2006;127(3):119.
  6. Molinari, M., Watt, K. D., Kruszyna, T., Nelson, R., Walsh, M., Huang, W. Y., Nashan, B., and Peltekian, K. Acute liver failure induced by green tea extracts: case report and review of the literature. Liver Transpl. 2006;12(12):1892-1895. PubMed
  7. Federico, A., Tiso, A., and Loguercio, C. A case of hepatotoxicity caused by green tea. Free Radic.Biol Med 8-1-2007;43(3):474. PubMed
  8. Sarma, D. N., Barrett, M. L., Chavez, M. L., Gardiner, P., Ko, R., Mahady, G. B., Marles, R. J., Pellicore, L. S., Giancaspro, G. I., and Low, Dog T. Safety of green tea extracts : a systematic review by the US Pharmacopeia. Drug Saf 2008;31(6):469-484. PubMed
  9. Rohde, J., Jacobsen, C., and Kromann-Andersen, H. [Toxic hepatitis triggered by green tea]. Ugeskr.Laeger 1-17-2011;173(3):205-206.
  10. Yellapu, R. K., Mittal, V., Grewal, P., Fiel, M., and Schiano, T. Acute liver failure caused by 'fat burners' and dietary supplements: a case report and literature review. Can.J.Gastroenterol. 2011;25(3):157-160. PubMed
  11. Health Canada. Health Product Info Watch. October 2016; 5-6. Available at: http://www.hc-sc.gc.ca/dhp-mps/medeff/bulletin/hpiw-ivps_2016-10-eng.php#a15.
  12. Oketch-Rabah HA, Roe AL, Rider CV, et al. United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts. Toxicol Rep. 2020;7:386-402. PubMed
  13. Pochet S, Lechon AS, Lescrainier C, et al. Herb-anticancer drug interactions in real life based on VigiBase, the WHO global database. Sci Rep 2022;12(1):14178. PubMed
Moderate

PHENYTOIN (Dilantin)

2 of 2
Theoretically, green tea might reduce the effects of phenytoin and increase the risk for convulsions.
Green tea contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenytoin. The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.
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 Sesquient (fosphenytoin). Once it's in your body, fosphenytoin is converted into phenytoin, the active seizure-control medicine, so any concern that applies to phenytoin applies here too. The worry on file is that the caffeine in green tea might slightly blunt how well phenytoin holds your seizures in check, which could theoretically raise the chance of a breakthrough seizure.

I want to be honest about how weak this signal is. It comes from animal lab work, not human studies, and the exact reason isn't clear. Because phenytoin is a drug where small changes can matter, enjoying a normal cup or two of green tea is unlikely to cause trouble, but loading up on concentrated green tea or caffeine pills is where I'd be more cautious. Run it by your pharmacist or neurologist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Jankiewicz, K., Chroscinska-Krawczyk, M., Blaszczyk, B., and Czuczwar, S. J. [Caffeine and antiepileptic drugs: experimental and clinical data]. Przegl.Lek. 2007;64(11):965-967.
  2. Chroscinska-Krawczyk, M., Jargiello-Baszak, M., Walek, M., Tylus, B., and Czuczwar, S. J. Caffeine and the anticonvulsant potency of antiepileptic drugs: experimental and clinical data. Pharmacol.Rep. 2011;63(1):12-18. PubMed

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

Green Tea Also Interacts With Other Medications

Green Tea has 13 major, 904 moderate, 375 minor 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.

Major 13 Moderate 904 Minor 375 No known interaction 1,538 (incl. Fosphenytoin Sodium)
Taking anything else?

Check Another of Your Medications Against Green Tea

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

From our Q&A

Questions About Green Tea or Fosphenytoin Sodium

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Green Tea or Fosphenytoin Sodium, 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 Fosphenytoin Sodium

This page covers Green Tea 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 Green Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 9,084 real supplement products containing Green Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Green Tea. Your product may carry other ingredients that interact with Fosphenytoin Sodium too, on top of Green Tea — 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 Green Tea 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 Green Tea
Top 5%

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

29 days ago today
Medication Fosphenytoin Sodium
Top 5%

#93 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 Green Tea

What is Green Tea?

Green Tea
  • Antioxidant support
  • Weight loss
  • Heart health
  • Mental alertness
  • Cancer risk reduction

Green tea is a popular beverage rich in antioxidants called catechins, and drinking it in normal amounts is considered safe for most people. Concentrated green tea extracts are a different story—they may help modestly with weight or heart health for some, but high doses have been linked to rare liver problems. Talk to your pharmacist or doctor before taking green tea supplements, especially if you have liver concerns or are pregnant.

Read the full Green Tea monograph & all interactions
Keep checking

Other Drugs & Green Tea

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

13Major
904Moderate
375Minor
1,537No known interaction
13 Major 904 Moderate 375 Minor 1,537 No interaction
Major

13 interactions

Moderate

904 interactions

Showing 60 of 904 moderate interactions — see all 904 on the Green Tea page.

Minor

375 interactions

Showing 60 of 375 minor interactions — see all 375 on the Green Tea page.

No interaction 1,537 drugs checked — show the list

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

Showing the 60 most looked-up of 1,537 medications checked with no known interaction — see the full Green Tea list.

See the full Green Tea 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
Green Tea 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 Green Tea and Fosphenytoin Sodium Together: Common Questions

Can you take Green Tea 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 Green Tea and Fosphenytoin Sodium?
Fosphenytoin Sodium belongs to more than one drug category, and Green Tea 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 Green Tea 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

Still Have a Question About Fosphenytoin Sodium and Green Tea?

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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.