Drug & supplement interaction

Griffonia Simplicifolia + Isocarboxazid

Isocarboxazid brand name: Marplan.

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

Isocarboxazid falls into 2 drug categories that Griffonia Simplicifolia can interact with; the most serious is rated moderate. Theoretically, taking Griffonia simplicifolia seed extract with antidepressant drugs might increase the risk of serotonergic adverse effects, such as serotonin syndrome and cerebral vasoconstrictive disorders such as Call-Fleming syndrome.

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

Griffonia Simplicifolia and Isocarboxazid

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

Why Are There 2 Interactions?

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

Moderate

ANTIDEPRESSANT DRUGS

1 of 2

Why this applies to Isocarboxazid

Isocarboxazid falls under ANTIDEPRESSANT DRUGS — the group Griffonia Simplicifolia interacts with.

Theoretically, taking Griffonia simplicifolia seed extract with antidepressant drugs might increase the risk of serotonergic adverse effects, such as serotonin syndrome and cerebral vasoconstrictive disorders such as Call-Fleming syndrome.
Griffonia simplicifolia seed extract contains 5-HTP. Taking 5-HTP with antidepressant drugs increases the risk of serotonergic adverse effects.
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

This is one pairing I'd be especially careful with. Isocarboxazid (Marplan) is an MAO inhibitor, which means it blocks the enzyme that normally breaks down serotonin in your brain. Griffonia seed extract supplies 5-HTP, the raw material your body uses to make serotonin. So you'd be adding more serotonin while also slowing down its cleanup, and that combination can push serotonin too high.

When serotonin climbs too far, it can trigger what we call serotonin syndrome: agitation, a racing heart, sweating, shivering, muscle twitching, confusion, and dangerously high blood pressure. To be clear, this concern is based on how these two work in theory, not hard human studies, but with an MAO inhibitor the risk is real enough that I would not combine them. Please check with your doctor or pharmacist before adding any 5-HTP product.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
  2. Lemaire PA, Adosraku RK. An HPLC method for the direct assay of the serotonin precursor, 5-hydroxytrophan, in seeds of Griffonia simplicifolia. Phytochem Anal 2002;13(6):333-7.
Moderate

MONOAMINE OXIDASE INHIBITORS (MAOIs)

2 of 2

Isocarboxazid also falls under MONOAMINE OXIDASE INHIBITORS (MAOIs).

Theoretically, taking Griffonia simplicifolia seed extract with MAOIs might increase the risk of serotonergic adverse effects, such as serotonin syndrome and cerebral vasoconstrictive disorders such as Call-Fleming syndrome.
Griffonia simplicifolia seed extract contains 5-HTP. Taking 5-HTP with MAOIs increases the risk of serotonergic adverse effects.
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 heart of it: isocarboxazid (Marplan) is an MAO inhibitor, which means it blocks the enzyme that breaks down serotonin in your brain. Griffonia seed extract supplies 5-HTP, which your body turns straight into more serotonin. Put those two together and you can end up with too much serotonin piling up, which is the real concern here.

That can lead to serotonin syndrome, with symptoms like agitation, a racing heart, sweating, shivering, muscle twitching, confusion, and in serious cases dangerously high blood pressure. While this warning is based on how the drugs work rather than lots of human studies, MAOIs are powerful and unforgiving, so I'd treat this combination as one to avoid. Please check with your doctor or pharmacist before adding any Griffonia or 5-HTP product.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. PubMed
  2. Pardo JV. Mania following addition of hydroxytryptophan to monoamine oxidase inhibitor. Gen Hosp Psychiatry 2012;34(1):102.e13-4. PubMed
  3. Lemaire PA, Adosraku RK. An HPLC method for the direct assay of the serotonin precursor, 5-hydroxytrophan, in seeds of Griffonia simplicifolia. Phytochem Anal 2002;13(6):333-7.

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

Griffonia Simplicifolia Also Interacts With Other Medications

Griffonia Simplicifolia has 316 moderate known drug interactions in our database — the Isocarboxazid one above is among them. If you take anything else, check it against the full list below.

Moderate 316 No known interaction 2,514 (incl. Isocarboxazid)
Taking anything else?

Check Another of Your Medications Against Griffonia Simplicifolia

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

Everything else you take

See Every Supplement That Interacts With Isocarboxazid

This page covers Griffonia Simplicifolia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isocarboxazid page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Bitter Orange (major), Brewer's Yeast (major) and Cowhage (major).

By severity: 14 major · 55 moderate · 12 minor.

From our pharmacist’s overview on the Isocarboxazid page

“Isocarboxazid (Marplan) is an MAOI antidepressant, and that drug class carries some of the sharpest supplement and food hazards in the pharmacy, so read this list closely rather than skimming it. Fourteen of the 81 entries rate major, and most of the danger runs through tyramine.”

Reviewed by 2 · Jul 18, 2026

Open the Isocarboxazid interaction page

One more smart check

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

We hold 3 real supplement products containing Griffonia Simplicifolia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Griffonia Simplicifolia. Your product may carry other ingredients that interact with Isocarboxazid too, on top of Griffonia Simplicifolia — 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 Griffonia Simplicifolia and Isocarboxazid 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 Griffonia Simplicifolia
Top half

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

29 days ago today
Medication Isocarboxazid
Steady interest

#2,419 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 Griffonia Simplicifolia

What is Griffonia Simplicifolia?

Griffonia Simplicifolia
  • Low mood
  • Sleep problems
  • Anxiety
  • Appetite control
  • Headaches

Griffonia simplicifolia is a West African shrub whose seeds are a natural source of 5-HTP, a building block of the brain chemical serotonin. Some people use it for mood, sleep, and appetite, but high-quality human evidence is limited, and it should not replace prescribed treatment. Talk with your pharmacist or doctor before using it, especially if you take medicines that affect serotonin.

Read the full Griffonia Simplicifolia monograph & all interactions
Medication

About Isocarboxazid

What Is Isocarboxazid Used For?

Brand name: Marplan

Marplan (isocarboxazid) is indicated for the treatment of depression — specifically, major depressive disorder. Because it carries serious risks, it is not a first-choice antidepressant. Marplan is generally reserved for patients who have not responded adequately to other antidepressants.

Clinical trials showed Marplan to be effective in adult outpatients with major depressive disorder, including those whose depression was accompanied by anxiety symptoms such as panic or phobias. Marplan is not approved for use in children or adolescents.

See full Isocarboxazid drug information
Keep checking

Other Drugs & Griffonia Simplicifolia

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

0Major
316Moderate
0Minor
2,513No known interaction
316 Moderate 2,513 No interaction
Moderate

316 interactions

Showing 60 of 316 moderate interactions — see all 316 on the Griffonia Simplicifolia page.

No interaction 2,513 drugs checked — show the list

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

Showing the 60 most looked-up of 2,513 medications checked with no known interaction — see the full Griffonia Simplicifolia list.

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

Can you take Griffonia Simplicifolia with Isocarboxazid?
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 Griffonia Simplicifolia and Isocarboxazid?
Isocarboxazid belongs to more than one drug category, and Griffonia Simplicifolia 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 Griffonia Simplicifolia and Isocarboxazid 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 Isocarboxazid and Griffonia Simplicifolia?

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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.