Drug & supplement interaction

Ginkgo + Proguanil

Proguanil brand name: Paludrine.

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

Proguanil falls into 2 drug categories that Ginkgo can interact with; the most serious is rated moderate. Theoretically, taking ginkgo with drugs that lower the seizure threshold might increase the risk for convulsions.

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

Ginkgo and Proguanil

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

Why Are There 2 Interactions?

Ginkgo interacts with whole categories of medication. Proguanil falls into 2 of those categories, so it can interact with Ginkgo 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 Proguanil

Proguanil 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

Here's the connection with Proguanil (often combined with atovaquone as Malarone for malaria prevention). Ginkgo can slightly lower the seizure threshold, meaning it may make seizures a touch more likely in people who are prone to them. Proguanil is grouped among medicines that can also nudge that threshold down, so the worry is that combining the two could, in theory, raise the chance of a convulsion.

I want to keep this in perspective. This is theoretical and based only on scattered anecdotal reports. Ginkgo leaf extract contains just trace amounts of the seizure-related compound (ginkgo seeds are the real concern). For most people without an epilepsy history, this is unlikely to be a problem. Still, if you've ever had seizures, check with your pharmacist or doctor before pairing them.

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
Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

2 of 2

Proguanil also falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES.

Theoretically, ginkgo might decrease levels of drugs metabolized by CYP2C19.
Some clinical research shows that a specific ginkgo leaf extract (Remembrance, Herbs Product LTD) 140 mg twice daily can induce CYP2C19 enzymes and potentially decrease levels of drugs metabolized by these enzymes. However, other clinical research shows that taking ginkgo 120 mg twice daily for 12 days has no effect on levels of drugs metabolized by CYP2C19.
Severity Moderate Likelihood Probable Evidence B

Interaction 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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's a twist worth knowing about Proguanil (Paludrine), which you'd typically take to help prevent malaria. Proguanil is actually a prodrug. Your body relies on the enzyme CYP2C19 to convert it into its active form, cycloguanil, which is the part that does the heavy lifting against the malaria parasite.

Ginkgo may speed up (induce) that same CYP2C19 enzyme. Normally faster clearing means weaker drug, but because Proguanil needs that enzyme to switch on, the picture is muddier, and the research here is mixed and mostly theoretical. Some studies show an effect, others show none. Since this is for malaria prevention, you don't want anything undercutting it. Please check with your pharmacist or doctor before pairing the two.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yin OQ, Tomlinson B, Waye MM, et al. Pharmacogenetics and herb-drug interactions: experience with Ginkgo biloba and omeprazole. Pharmacogenetics 2004;14:841-50. PubMed
  2. Lei, H. P., Wang, G., Wang, L. S., Ou-yang, D. S., Chen, H., Li, Q., Zhang, W., Tan, Z. R., Fan, L., He, Y. J., and Zhou, H. H. Lack of effect of Ginkgo biloba on voriconazole pharmacokinetics in Chinese volunteers identified as CYP2C19 poor and extensiv

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 Proguanil one above is among them. If you take anything else, check it against the full list below.

Major 1 Moderate 1,264 No known interaction 1,565 (incl. Proguanil)
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 Proguanil

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 Proguanil, 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 Proguanil

This page covers Ginkgo only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Proguanil page lists 54 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Adrafinil (moderate), Artichoke (moderate), Bacopa (moderate) and Baikal Skullcap (moderate).

By severity: 1 major · 40 moderate · 13 minor.

From our pharmacist’s overview on the Proguanil page

“Malaria prophylaxis leaves little margin for error, so the 54 supplements and herbs on file against proguanil (Paludrine) deserve a careful read rather than a shrug. The single major-rated entry is activated charcoal, which binds medicines in the gut and can cut proguanil exposure enough to undermine your protection.”

Reviewed by 2 · Jul 18, 2026

Open the Proguanil 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 Proguanil 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 Proguanil 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%

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

29 days ago today
Medication Proguanil
Steady interest

#2,653 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 Proguanil, 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 Proguanil supplement interactions › Every supplement checked against Proguanil, 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 Proguanil Together: Common Questions

Can you take Ginkgo with Proguanil?
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 Ginkgo and Proguanil?
Proguanil belongs to more than one drug category, and Ginkgo 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 Ginkgo and Proguanil 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 Proguanil 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.