Drug & supplement interaction

Vinpocetine + Fosphenytoin

Fosphenytoin brand name: Cerebyx.

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

Vinpocetine has a moderate interaction with Fosphenytoin. Theoretically, vinpocetine might increase levels of drugs metabolized by CYP2C9.

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

Vinpocetine and Fosphenytoin

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

Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

Why this applies to Fosphenytoin

Fosphenytoin falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Vinpocetine interacts with.

Theoretically, vinpocetine might increase levels of drugs metabolized by CYP2C9.
In vitro research shows that vinpocetine weakly inhibits CYP2C9. However, 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 gist for fosphenytoin: once it's in your body, it converts to phenytoin, which your liver clears partly through an enzyme called CYP2C9. Lab studies hint that vinpocetine may weakly block that enzyme. If that happened in real life, phenytoin could clear a little slower and creep up to higher levels, possibly causing more side effects like dizziness, slurred speech, unsteady walking, double vision, or drowsiness.

The important caveat: this is only test-tube evidence and hasn't actually been seen in people. Still, phenytoin is a narrow-window drug where small changes can matter, and its levels are often checked with blood tests. So before adding vinpocetine, please run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kong L, Song C, Ye L, et al. The Effect of Vinpocetine on Human Cytochrome P450 Isoenzymes by Using a Cocktail Method. Evid Based Complement Alternat Med. 2016;2016:5017135. 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

Vinpocetine Also Interacts With Other Medications

Vinpocetine has 207 moderate known drug interactions in our database — the Fosphenytoin one above is one of them. If you take anything else, check it against the full list below.

Moderate 207 No known interaction 2,623 (incl. Fosphenytoin)
Taking anything else?

Check Another of Your Medications Against Vinpocetine

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

Everything else you take

See Every Supplement That Interacts With Fosphenytoin

This page covers Vinpocetine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin page lists 205 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 · 172 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin page

“St. John's wort is the entry I would flag first with fosphenytoin (Cerebyx).”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin interaction page

One more smart check

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

We hold 630 real supplement products containing Vinpocetine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Vinpocetine. Your product may carry other ingredients that interact with Fosphenytoin too, on top of Vinpocetine — 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 Vinpocetine and Fosphenytoin 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 Vinpocetine
Top 25%

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

29 days ago today
Medication Fosphenytoin
Top 25%

#352 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 Vinpocetine

What is Vinpocetine?

Vinpocetine
  • Memory and cognitive support
  • Brain blood flow
  • Stroke recovery
  • Age-related memory decline
  • Tinnitus and hearing concerns

Vinpocetine is a lab-made compound based on a chemical from the periwinkle plant, and it is marketed mainly for memory and brain health. The evidence behind these uses is limited and not strong, and U.S. regulators have warned that it should be avoided by people who are pregnant or could become pregnant. Talk with your pharmacist or doctor before trying it.

Read the full Vinpocetine monograph & all interactions
Medication

About Fosphenytoin Injection

What Is Fosphenytoin Injection Used For?

Brand name: Cerebyx

Fosphenytoin Injection treats generalized tonic-clonic status epilepticus. This is a dangerous, prolonged seizure emergency. It is also used to prevent and treat seizures that happen during neurosurgery.

It can be used short-term in place of oral phenytoin. It should be used only when taking phenytoin by mouth is not possible.

See full Fosphenytoin Injection drug information
Keep checking

Other Drugs & Vinpocetine

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

0Major
207Moderate
0Minor
2,622No known interaction
207 Moderate 2,622 No interaction
Moderate

207 interactions

Showing 60 of 207 moderate interactions — see all 207 on the Vinpocetine page.

No interaction 2,622 drugs checked — show the list

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

Showing the 60 most looked-up of 2,622 medications checked with no known interaction — see the full Vinpocetine list.

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

Can you take Vinpocetine with Fosphenytoin?
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 Vinpocetine and Fosphenytoin 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 and Vinpocetine?

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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.