Drug & supplement interaction

Ginkgo + Iohexol

Iohexol brand names: Omnipaque, Oraltag.

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

Ginkgo has a moderate interaction with Iohexol. Theoretically, taking ginkgo with drugs that lower the seizure threshold might increase the risk for convulsions.

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

Ginkgo and Iohexol

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

Moderate

SEIZURE THRESHOLD LOWERING DRUGS

Why this applies to Iohexol

Iohexol falls under SEIZURE THRESHOLD LOWERING DRUGS — the group Ginkgo interacts with.

Theoretically, taking ginkgo with drugs that lower the seizure threshold might increase the risk for convulsions.
Ginkgo seeds contain ginkgotoxin. Large amounts of ginkgotoxin can cause neurotoxicity and seizure. Ginkgotoxin is present in much larger amounts in ginkgo seeds than leaves. Ginkgo leaf extract contains trace amounts of ginkgotoxin. The amount of ginkgotoxin in ginkgo leaf and leaf extract seems unlikely to cause toxicity. However, there are anecdotal reports of seizure occurring after use of ginkgo leaf both in patients without a history of seizure disorder and in those with previously well-controlled epilepsy.
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

Iohexol (brand names Omnipaque and Oraltag) is a contrast dye doctors use during X-rays and CT scans to help your body show up more clearly. One of its known, though uncommon, side effects is that it can slightly lower the seizure threshold, meaning it can make seizures a touch more likely in people who are already prone to them.

Here's the theory: ginkgo seeds contain a compound called ginkgotoxin that, in large amounts, can trigger seizures. Most ginkgo leaf supplements only have trace amounts, so they're unlikely to cause trouble. Still, there are a few anecdotal reports of seizures after ginkgo. The combined worry is mostly theoretical, but if you have a seizure history or an upcoming imaging scan, mention your ginkgo use to your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gregory PJ. Seizure associated with Ginkgo biloba? Ann Intern Med 2001;134:344.
  2. Granger AS. Ginkgo biloba precipitating epileptic seizures. Age Ageing 2001;30:523-5. PubMed
  3. Miwa H, Iijima M, Tanaka S, Mizuno Y. Generalized convulsions after consuming a large amount of gingko nuts. Epilepsia 2001;42:280-1. DOI
  4. Arenz A, Kelin M, Flehe K, et al. Occurrence of neurotoxic 4'-O-methylpyridoxine in ginkgo biloba leaves, ginkgo medications and Japanese ginkgo food. Planta Med 1996;62:548-51.
  5. Kupiec T, Raj V. Fatal seizures due to potential herb-drug interactions with Ginkgo biloba. J Anal Toxicol 2005:755-8. 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

Ginkgo Also Interacts With Other Medications

Ginkgo has 1 major, 1,264 moderate known drug interactions in our database — the Iohexol one above is one of them. If you take anything else, check it against the full list below.

Major 1 Moderate 1,264 No known interaction 1,565 (incl. Iohexol)
Taking anything else?

Check Another of Your Medications Against Ginkgo

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

From our Q&A

Questions About Ginkgo or Iohexol

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

This page covers Ginkgo only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Iohexol page lists 23 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Biofeedback (moderate), Coffee Charcoal (moderate), Dendrobium (moderate) and European Mandrake (moderate).

By severity: 1 major · 13 moderate · 9 minor.

From our pharmacist’s overview on the Iohexol page

“Iohexol (Omnipaque, Oraltag) is a contrast dye used to sharpen CT scans and other imaging, and its supplement list deserves genuine attention before an appointment. Of the 23 ingredients on file, 17 can change how drugs taken by mouth get absorbed, which matters most with the oral form, Oraltag, since altered absorption can muddy the s…”

Reviewed by 2 · Jul 18, 2026

Open the Iohexol interaction page

One more smart check

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

We hold 4,399 real supplement products containing Ginkgo, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ginkgo. Your product may carry other ingredients that interact with Iohexol too, on top of Ginkgo — 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 Ginkgo and Iohexol 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 Ginkgo
Top 5%

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

29 days ago today
Medication Iohexol
Top half

#1,078 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 Ginkgo

What is Ginkgo?

Ginkgo
  • Memory and cognitive support
  • Age-related mental decline
  • Circulation problems
  • Tinnitus (ringing in the ears)
  • Dizziness or vertigo

Ginkgo is one of the world's most popular herbal supplements, mostly taken to support memory and circulation. The evidence for these uses is mixed and generally weak, and it is not proven to prevent memory loss or dementia. It is usually well tolerated in healthy adults, but it can thin the blood, so talk to your pharmacist or doctor before using it.

Read the full Ginkgo monograph & all interactions
Keep checking

Other Drugs & Ginkgo

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

1Major
1,264Moderate
0Minor
1,564No known interaction
1 Major 1,264 Moderate 1,564 No interaction
Major

1 interaction

Moderate

1,264 interactions

Showing 60 of 1,264 moderate interactions — see all 1,264 on the Ginkgo page.

No interaction 1,564 drugs checked — show the list

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

Showing the 60 most looked-up of 1,564 medications checked with no known interaction — see the full Ginkgo list.

See the full Ginkgo interactions page
See every supplement checked against Iohexol, 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
Ginkgo monograph › Uses, safety, and every drug interaction in one place Iohexol supplement interactions › Every supplement checked against Iohexol, 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 Ginkgo and Iohexol Together: Common Questions

Can you take Ginkgo with Iohexol?
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 Ginkgo and Iohexol 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 Iohexol and Ginkgo?

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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.