Drug & supplement interaction

Pinellia Ternata + Phenytoin

Phenytoin brand names: Dilantin Kapseals, Dilantin, Di-Phen, Dilantin Infatabs, Phenytek, and others.

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

Pinellia Ternata has a moderate interaction with Phenytoin. Evidence from animal research shows that a Pinellia ternata preparation decreases activity and increases sleeping time.

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

Pinellia Ternata and Phenytoin

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CNS DEPRESSANTS

Why this applies to Phenytoin

Phenytoin falls under CNS DEPRESSANTS — the group Pinellia Ternata interacts with.

Evidence from animal research shows that a Pinellia ternata preparation decreases activity and increases sleeping time. Theoretically, Pinellia ternata can potentiate the therapeutic effect of CNS depressants. Some of these medications include antihistamines, barbiturates, benzodiazepines, tricyclic antidepressants, and others.
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 of it. In animal studies, a processed form of Pinellia ternata seemed to calm the nervous system and lengthen sleep. The thinking is that pairing it with medicines that already slow the brain could add to that drowsy effect. Phenytoin (Dilantin) isn't a sedative by design, but it can cause sleepiness, dizziness, and unsteadiness, so in theory those could feel stronger together.

I want to be honest with you: this is based only on lab and animal work, not real human cases, so it's quite uncertain. Still, phenytoin is a drug where blood levels need to stay in a narrow window, so I'd never want you guessing. Please run this past your doctor or pharmacist before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lin S, Nie B, Yao G, Yang H, Ye R, Yuan Z. Pinellia ternata (Thunb.) makino preparation promotes sleep by increasing REM sleep. Nat Prod Res. 2019;33(22):3326-3329. 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

Pinellia Ternata Also Interacts With Other Medications

Pinellia Ternata has 255 moderate known drug interactions in our database — the Phenytoin one above is one of them. If you take anything else, check it against the full list below.

Moderate 255 No known interaction 2,575 (incl. Phenytoin)
Taking anything else?

Check Another of Your Medications Against Pinellia Ternata

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

From our Q&A

Questions About Pinellia Ternata or Phenytoin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Pinellia Ternata or Phenytoin, 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 Phenytoin

This page covers Pinellia Ternata only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenytoin page lists 224 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 · 187 moderate · 28 minor.

From our pharmacist’s overview on the Phenytoin page

“Phenytoin (Dilantin) is a seizure medicine with a narrow therapeutic index, meaning small changes in its blood level can bring seizures back or tip over into toxicity, so I treat its supplement list with real seriousness. The biggest group, 78 ingredients, piles on sedation, and alcohol, kava, and GHB all rate major for exactly that re…”

Reviewed by 2 · Jul 18, 2026

Open the Phenytoin interaction page

One more smart check

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

We hold 20 real supplement products containing Pinellia Ternata, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Pinellia Ternata. Your product may carry other ingredients that interact with Phenytoin too, on top of Pinellia Ternata — 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 Pinellia Ternata and 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 Pinellia Ternata
Top half

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

29 days ago today
Medication Phenytoin
Steady interest

#1,761 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 Pinellia Ternata

What is Pinellia Ternata?

  • Nausea and vomiting
  • Cough with phlegm
  • Morning sickness (traditional use)
  • Digestive upset and bloating
  • Throat discomfort

Pinellia ternata is a tuber used in traditional Chinese medicine, most often for nausea, vomiting, and phlegmy coughs, and almost always as part of multi-herb formulas. The raw plant is toxic and must be specially processed before use, so it should only be used under qualified guidance. Solid human evidence is limited, and it should be avoided in pregnancy and breastfeeding.

Read the full Pinellia Ternata monograph & all interactions
Medication

About Phenytoin

What Is Phenytoin Used For?

Brand names: Dilantin Kapseals, Dilantin, Di-Phen, Dilantin Infatabs, Phenytek, Dilantin injection

Phenytoin is used to treat and prevent seizures. The specific types covered depend on the formulation. Oral extended-release capsules (including Phenytek), chewable tablets (including Dilantin Infatabs and Phenytoin Infatabs), and oral suspension (including Dilantin-125) are used for tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures; most oral forms also cover prevention and treatment of seizures occurring during or after neurosurgery. Chewable tablets and some capsule formulations also cover complex partial seizures.

Parenteral (injectable) phenytoin sodium is used for generalized tonic-clonic status epilepticus (a prolonged, life-threatening seizure emergency) and for prevention and treatment of seizures during neurosurgery. The IV form can also substitute short-term for oral phenytoin when a patient cannot take it by mouth.

See full Phenytoin drug information
Keep checking

Other Drugs & Pinellia Ternata

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

0Major
255Moderate
0Minor
2,574No known interaction
255 Moderate 2,574 No interaction
Moderate

255 interactions

Showing 60 of 255 moderate interactions — see all 255 on the Pinellia Ternata page.

No interaction 2,574 drugs checked — show the list

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

Showing the 60 most looked-up of 2,574 medications checked with no known interaction — see the full Pinellia Ternata list.

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

Can you take Pinellia Ternata with 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.
How serious is the Pinellia Ternata and 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

Still Have a Question About Phenytoin and Pinellia Ternata?

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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.