Drug & supplement interaction

Bacopa + 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

Phenytoin falls into 2 drug categories that Bacopa can interact with; the most serious is rated moderate. Theoretically, bacopa might increase the levels and adverse effects of CYP2C19 substrates.

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

Bacopa and Phenytoin

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

Why Are There 2 Interactions?

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

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 2

Why this applies to Phenytoin

Phenytoin falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Bacopa interacts with.

Theoretically, bacopa might increase the levels and adverse effects of CYP2C19 substrates.
In vitro evidence suggests that bacopa extract can moderately and non-competitively inhibit CYP2C19 enzymes. It is not known whether this is clinically significant.
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 if you're taking Dilantin (phenytoin) and thinking about bacopa. Your body partly relies on a liver enzyme called CYP2C19 to clear phenytoin. In lab tests (test tubes, not people), bacopa seemed to slow that enzyme down a bit. If that happened in real life, phenytoin could build up and push you toward side effects like dizziness, drowsiness, unsteady walking, slurred speech, or jerky eye movements.

I want to be honest, though: this is theoretical and based only on lab data, so we don't know if it matters in actual patients. Still, phenytoin has a narrow safety window where small changes count. Please check with your pharmacist or doctor before adding bacopa, and never adjust your dose on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ramasamy S, Kiew LV, Chung LY. Inhibition of human cytochrome P450 enzymes by Bacopa monnieri standardized extract and constituents. Molecules 2014;19(2):2588-601. PubMed
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

2 of 2

Phenytoin also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, bacopa might increase the levels and adverse effects of CYP2C9 substrates.
Research on the effect of bacopa extracts on CYP2C9 enzymes is conflicting. Some in vitro evidence suggests that bacopa extract can moderately and non-competitively inhibit CYP2C9, while other in vitro evidence suggests that any effect is unlikely to be clinically significant.
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 if you take bacopa with phenytoin. Phenytoin is cleared from your body mainly by a liver enzyme called CYP2C9. Lab studies hint that bacopa might slow that enzyme down a bit. If that happened in real life, phenytoin could build up and push you toward side effects like dizziness, drowsiness, unsteady walking, slurred speech, or eye-movement problems (nystagmus).

I want to keep this in perspective, though. This warning comes only from test-tube and animal studies, and even those results disagree with each other. It's a theoretical concern, not something proven in people. Still, because phenytoin has a narrow safety window where small shifts matter, please check with your doctor or pharmacist before adding bacopa.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kar A, Pandit S, Mukherjee K, Bahadur S, Mukherjee PK. Safety assessment of selected medicinal food plants used in Ayurveda through CYP450 enzyme inhibition study. J Sci Food Agric 2017;97(1):333-40. doi: 10.1002/jsfa.7739. PubMed
  2. Ramasamy S, Kiew LV, Chung LY. Inhibition of human cytochrome P450 enzymes by Bacopa monnieri standardized extract and constituents. Molecules 2014;19(2):2588-601. 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

Bacopa Also Interacts With Other Medications

Bacopa has 916 moderate, 13 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 916 Minor 13 No known interaction 1,901 (incl. Phenytoin)
Taking anything else?

Check Another of Your Medications Against Bacopa

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

From our Q&A

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

We hold 1,420 real supplement products containing Bacopa, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bacopa. Your product may carry other ingredients that interact with Phenytoin too, on top of Bacopa — 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 Bacopa 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 Bacopa
Top 10%

#140 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 Bacopa

What is Bacopa?

Bacopa
  • Memory and cognitive support
  • Anxiety and stress
  • ADHD symptoms
  • Age-related memory decline
  • General brain health

Bacopa is an Ayurvedic herb most often used for memory and thinking. Some small studies suggest it may modestly help memory when taken regularly for several weeks, but the evidence is limited and quality varies. It is generally well tolerated but can cause stomach upset, and it should be avoided in pregnancy and breastfeeding due to a lack of safety data.

Read the full Bacopa 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 & Bacopa

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

0Major
916Moderate
13Minor
1,900No known interaction
916 Moderate 13 Minor 1,900 No interaction
Moderate

916 interactions

Showing 60 of 916 moderate interactions — see all 916 on the Bacopa page.

Minor

13 interactions

No interaction 1,900 drugs checked — show the list

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

Showing the 60 most looked-up of 1,900 medications checked with no known interaction — see the full Bacopa list.

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

Can you take Bacopa 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 Bacopa and Phenytoin?
Phenytoin belongs to more than one drug category, and Bacopa 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 Bacopa 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 Bacopa?

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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.