Drug & supplement interaction

Dendrobium + Phenytoin

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

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

Phenytoin falls into 2 drug categories that Dendrobium can interact with; the most serious is rated moderate. The dendrobium constituent dendrobine is reported to have convulsant effects.

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

Dendrobium and Phenytoin

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

Why Are There 2 Interactions?

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

Moderate

SEIZURE THRESHOLD LOWERING DRUGS

1 of 2

Why this applies to Phenytoin

Phenytoin falls under SEIZURE THRESHOLD LOWERING DRUGS — the group Dendrobium interacts with.

The dendrobium constituent dendrobine is reported to have convulsant effects. Theoretically, combining dendrobium with pro-convulsant drugs might increase the risk of seizure. Some drugs that lower the seizure threshold include anesthetics (propofol, others), antiarrhythmics (mexiletine), antibiotics (amphotericin, penicillin, cephalosporins, imipenem), antidepressants (bupropion, others), antihistamines (cyproheptadine, others), immunosuppressants (cyclosporine), narcotics (fentanyl, others), stimulants (methylphenidate), theophylline, 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 thing to keep in mind: you take phenytoin to raise the threshold for seizures and keep your brain's electrical activity calm. Dendrobium contains a natural compound called dendrobine, which lab reports suggest can actually do the opposite and make seizures more likely. So the worry isn't that one changes how the other is broken down. It's that dendrobium could work against the very job phenytoin is doing, potentially making a breakthrough seizure more likely.

I'll be honest, this is theoretical and based mostly on the pharmacology, not on real patient cases, so don't panic. Still, since phenytoin is a finicky drug where steady control really matters, I'd skip dendrobium and run it by your doctor or pharmacist first rather than risk undermining your seizure control.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Dr. Duke's Phytochemical and Ethnobotanical Databases. Available at: http://www.ars-grin.gov/duke/.
Moderate

ANTICONVULSANTS

2 of 2

Phenytoin also falls under ANTICONVULSANTS.

The dendrobium constituent dendrobine is reported to have convulsant effects. Theoretically, combining dendrobium with anticonvulsant drugs might decrease drug effectiveness and increase the risk of seizure. Some anticonvulsant drugs include phenobarbital, primidone (Mysoline), valproic acid (Depakene), gabapentin (Neurontin), carbamazepine (Tegretol), phenytoin (Dilantin), 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 concern with pairing Dendrobium and your phenytoin. One of the natural compounds in this orchid, called dendrobine, has been reported to cause convulsant (seizure-promoting) effects in lab settings. Since phenytoin's whole job is to calm down abnormal electrical activity in your brain and keep seizures away, taking something that could nudge in the opposite direction could theoretically work against it. The worry isn't more side effects, it's less seizure protection, meaning a breakthrough seizure.

I want to be honest though: this is theoretical, based on how the plant behaves in the lab, not on real patient reports. Still, phenytoin is a drug where even small shifts matter, so I wouldn't add Dendrobium without first checking with your doctor or pharmacist.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Dr. Duke's Phytochemical and Ethnobotanical Databases. Available at: http://www.ars-grin.gov/duke/.

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

Dendrobium Also Interacts With Other Medications

Dendrobium has 460 moderate, 148 minor known drug interactions in our database — the Phenytoin one above is among them. If you take anything else, check it against the full list below.

Moderate 460 Minor 148 No known interaction 2,222 (incl. Phenytoin)
Taking anything else?

Check Another of Your Medications Against Dendrobium

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

From our Q&A

Questions About Dendrobium 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 Dendrobium 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 Dendrobium 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 Dendrobium as Part of a Dietary Supplement Product? Check It for Interactions

We hold 117 real supplement products containing Dendrobium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Dendrobium. Your product may carry other ingredients that interact with Phenytoin too, on top of Dendrobium — 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 Dendrobium 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 Dendrobium
Top half

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

29 days ago today
Medication Phenytoin
Top 25%

#529 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 Dendrobium

What is Dendrobium?

  • Dry mouth and thirst
  • Supporting digestion
  • General tonic/vitality
  • Eye and skin health
  • Recovery after illness

Dendrobium is a group of orchids long used in traditional Chinese medicine, often to moisten the body and as a general tonic. Human evidence for its modern health claims is very limited, so it should be viewed as a traditional remedy rather than a proven treatment. Talk to your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding because safety isn't known.

Read the full Dendrobium monograph & all interactions
Medication

About Phenytoin

What Is Phenytoin Used For?

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

Phenytoin treats seizures. Oral products are used for generalized tonic-clonic (grand mal) seizures and for psychomotor (temporal lobe) or complex partial seizures. Most oral products are also used to prevent and treat seizures during or after neurosurgery.

Phenytoin Sodium Injection is used for generalized tonic-clonic status epilepticus (a prolonged, dangerous seizure emergency). It is also used for seizures during neurosurgery. The injection should be used only when taking phenytoin by mouth is not possible. Dilantin-125 and Phenytoin oral suspension are listed for tonic-clonic and psychomotor seizures.

See full Phenytoin drug information
Keep checking

Other Drugs & Dendrobium

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

0Major
460Moderate
148Minor
2,221No known interaction
460 Moderate 148 Minor 2,221 No interaction
Moderate

460 interactions

Showing 60 of 460 moderate interactions — see all 460 on the Dendrobium page.

Minor

148 interactions

Showing 60 of 148 minor interactions — see all 148 on the Dendrobium page.

No interaction 2,221 drugs checked — show the list

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

Showing the 60 most looked-up of 2,221 medications checked with no known interaction — see the full Dendrobium list.

See the full Dendrobium 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
Dendrobium 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 Dendrobium and Phenytoin Together: Common Questions

Can you take Dendrobium 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.
Why are there 2 interactions listed for Dendrobium and Phenytoin?
Phenytoin belongs to more than one drug category, and Dendrobium 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 Dendrobium 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 Dendrobium?

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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.