Drug & supplement interaction

Brussels Sprout + Olanzapine

Olanzapine brand name: Zyprexa.

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

Brussels Sprout has a moderate interaction with Olanzapine. Animal research suggests that Brussels sprout can induce cytochrome P450 1A2 (CYP1A2) activity.

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

Brussels Sprout and Olanzapine

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

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Why this applies to Olanzapine

Olanzapine falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Brussels Sprout interacts with.

Animal research suggests that Brussels sprout can induce cytochrome P450 1A2 (CYP1A2) activity. Theoretically, Brussels sprout might increase the clearance and decrease the effects of drugs metabolized by CYP1A2. Some drugs metabolized by CYP1A2 include clozapine (Clozaril), cyclobenzaprine (Flexeril), fluvoxamine (Luvox), haloperidol (Haldol), imipramine (Tofranil), mexiletine (Mexitil), olanzapine (Zyprexa), pentazocine (Talwin), propranolol (Inderal), tacrine (Cognex), theophylline, zileuton (Zyflo), zolmitriptan (Zomig), and others.
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: your body relies on an enzyme called CYP1A2 to clear olanzapine out of your system. Compounds in Brussels sprouts may nudge that enzyme to work a little faster. If that happens, olanzapine could be broken down quicker, which in theory means lower levels and a weaker effect. For someone managing schizophrenia or bipolar disorder, that could mean symptoms aren't as well controlled.

The good news is this is mostly based on animal and lab work, not human studies, so the real-world impact is uncertain and likely small. Eating Brussels sprouts as a normal part of meals shouldn't be a problem. Just keep your intake fairly steady and chat with your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wortelboer HM, de Kruif CA, van Iersel AAJ, et al. Effects of cooked Brussels sprouts on cytochrome P-450 profile and phase II enzymes in liver and small intestinal mucosa of the rat. Food Chem Toxicol 1992;30(1):17-27. 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

Brussels Sprout Also Interacts With Other Medications

Brussels Sprout has 240 moderate known drug interactions in our database — the Olanzapine one above is one of them. If you take anything else, check it against the full list below.

Moderate 240 No known interaction 2,590 (incl. Olanzapine)
Taking anything else?

Check Another of Your Medications Against Brussels Sprout

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

From our Q&A

Questions About Brussels Sprout or Olanzapine

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

This page covers Brussels Sprout only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Olanzapine page lists 160 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Indian Snakeroot (major), Lithium (major), Rauvolfia Vomitoria (major) and 1,3-dmaa (moderate).

By severity: 4 major · 118 moderate · 38 minor.

From our pharmacist’s overview on the Olanzapine page

“Olanzapine (Zyprexa) is an antipsychotic prescribed for schizophrenia and bipolar disorder, and adding supplements to it warrants genuine care. Four of the 160 ingredients on file rate major, and those four deserve your attention before anything else: lithium supplements raise the risk of serotonin syndrome, activated charcoal can trap…”

Reviewed by 2 · Jul 18, 2026

Open the Olanzapine interaction page

How much people look this up

Where Brussels Sprout and Olanzapine 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 Brussels Sprout
Steady interest

#1,209 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Olanzapine
Top 10%

#283 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 Brussels Sprout

What is Brussels Sprout?

  • General nutrition and fiber
  • Antioxidant support
  • Digestive health
  • Heart health support
  • Cancer-prevention interest

Brussels sprouts are a nutritious cruciferous vegetable rich in fiber, vitamin C, vitamin K, and plant compounds called glucosinolates. Eating them as part of a balanced diet is healthy and safe for most people, but supplement-style claims (like preventing cancer) are not well proven. If you take blood thinners or have thyroid concerns, talk with your pharmacist or doctor about your intake.

Read the full Brussels Sprout monograph & all interactions
Medication

About Olanzapine

What Is Olanzapine Used For?

Brand name: Zyprexa

Olanzapine treats schizophrenia and the manic or mixed episodes of bipolar I disorder in both adults and adolescents (ages 13–17). It can also be used alongside valproate or lithium to treat manic or mixed episodes in adults. When combined with fluoxetine, olanzapine tablets and orally disintegrating tablets are used to treat depressive episodes associated with bipolar I disorder and treatment-resistant depression in adults.

Olanzapine intramuscular injection (short-acting) is used by healthcare providers to quickly calm acute agitation in adults with schizophrenia or bipolar I mania. Zyprexa Relprevv — a separate, long-acting intramuscular formulation available only through a restricted program — is indicated specifically for the treatment of schizophrenia in adults.

See full Olanzapine drug information
Keep checking

Other Drugs & Brussels Sprout

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

0Major
240Moderate
0Minor
2,589No known interaction
240 Moderate 2,589 No interaction
Moderate

240 interactions

Showing 60 of 240 moderate interactions — see all 240 on the Brussels Sprout page.

No interaction 2,589 drugs checked — show the list

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

Showing the 60 most looked-up of 2,589 medications checked with no known interaction — see the full Brussels Sprout list.

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

Can you take Brussels Sprout with Olanzapine?
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 Brussels Sprout and Olanzapine 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 Olanzapine and Brussels Sprout?

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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.