Drug & supplement interaction

Brussels Sprout + Acetaminophen, Codeine, Doxylamine

Acetaminophen, Codeine, Doxylamine brand name: Mersyndol.

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

Acetaminophen, Codeine, Doxylamine falls into 3 drug categories that Brussels Sprout can interact with; the most serious is rated moderate. Animal research suggests that Brussels sprout can induce cytochrome P450 1A2 (CYP1A2) activity.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Brussels Sprout and Acetaminophen, Codeine, Doxylamine

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Brussels Sprout interacts with whole categories of medication. Acetaminophen, Codeine, Doxylamine falls into 3 of those categories, so it can interact with Brussels Sprout in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

1 of 3

Why this applies to Acetaminophen, Codeine, Doxylamine

Acetaminophen, Codeine, Doxylamine 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 honest scoop: the only flag here is that Brussels sprouts may gently speed up an enzyme called CYP1A2. That matters most for the doxylamine piece of Mersyndol, the sedating antihistamine that helps you sleep. In theory, faster clearance could make that drowsy, dry-mouth effect a touch weaker. The codeine and acetaminophen parts run mostly through different pathways (codeine through CYP2D6, acetaminophen through other routes), so they're largely unaffected here.

Now the reassuring part: this comes only from lab and animal studies, not from people, and you'd likely need far more than a normal dinner portion to notice anything. A regular serving of sprouts is very unlikely to change how this medicine works. If you eat large amounts often or have concerns, just check with your pharmacist.

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
Moderate

GLUCURONIDATED DRUGS

2 of 3

Acetaminophen, Codeine, Doxylamine also falls under GLUCURONIDATED DRUGS.

A cabbage and Brussels sprout-containing diet seems to boost elimination through glucuronide conjugation. Theoretically, these foods might also lower levels of other drugs that are metabolized through glucuronide conjugation, including acetaminophen (Tylenol, others) and oxazepam (Serax), haloperidol (Haldol), lamotrigine (Lamictal), morphine (MS Contin, Roxanol), zidovudine (AZT, Retrovir), and others.
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 the gist for your Mersyndol (which combines acetaminophen, codeine, and doxylamine). Brussels sprouts contain compounds that may slightly speed up one of the body's clearing pathways called glucuronidation. The acetaminophen part of this product is partly handled by that pathway, so in theory a diet heavy in Brussels sprouts could nudge acetaminophen levels down a touch and make the pain-relieving piece feel a little weaker.

Honestly though, this is mostly theoretical and based on diet studies, not strong human trials. Normal amounts of Brussels sprouts on your dinner plate are very unlikely to cause any real change in how Mersyndol works. If you're eating large amounts daily or taking concentrated extracts, just mention it to your pharmacist or doctor. Don't adjust your medication on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pantuck EJ, Pantuck CB, Anderson KE, et al. Effect of brussels sprouts and cabbage on drug conjugation. Clin Pharmacol Ther 1984;35:161-9. PubMed
Moderate

ACETAMINOPHEN (Tylenol, others)

3 of 3
A cabbage and Brussels sprout-containing diet can increase metabolism and decrease levels of acetaminophen. In clinical research, a diet that includes daily consumption of cabbage and Brussels sprout decreases acetaminophen levels by as much as 16%. This appears to occur due to a boost of elimination through glucuronide conjugation.
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 the simple version for your Mersyndol, which combines acetaminophen, codeine, and doxylamine. The interaction on file is really about the acetaminophen part. Eating cabbage and Brussels sprouts regularly seems to speed up how your body clears acetaminophen, lowering its blood levels by up to about 16% in research. In plain terms, the pain and fever relief from that ingredient could be a touch weaker if you're eating a lot of these vegetables every day.

Honestly, this is a small and fairly gentle effect, and normal amounts of Brussels sprouts in your meals aren't likely to cause a real problem. The codeine and doxylamine parts aren't involved here. If you feel like your medicine isn't working as well, don't change anything on your own. Just check in with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pantuck EJ, Pantuck CB, Anderson KE, et al. Effect of brussels sprouts and cabbage on drug conjugation. Clin Pharmacol Ther 1984;35:161-9. 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 Acetaminophen, Codeine, Doxylamine one above is among them. If you take anything else, check it against the full list below.

Moderate 240 No known interaction 2,590 (incl. Acetaminophen, Codeine, Doxylamine)
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.

Everything else you take

See Every Supplement That Interacts With Acetaminophen, Codeine, Doxylamine

This page covers Brussels Sprout only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Codeine, Doxylamine page lists 261 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Asarabacca (major), Beer (major) and Gamma-hydroxybutyrate (ghb) (major).

By severity: 11 major · 208 moderate · 42 minor.

From our pharmacist’s overview on the Acetaminophen, Codeine, Doxylamine page

“Mersyndol pairs acetaminophen with codeine and doxylamine, two sedating drugs in one tablet, so I read its interaction list with genuine vigilance. Of the 261 supplements and herbs on file, the biggest hazard is anything else that slows the brain: 78 ingredients add sedation, and that group holds several of the 11 major-rated entries,…”

Reviewed by 2 · Jul 18, 2026

Open the Acetaminophen, Codeine, Doxylamine interaction page

How much people look this up

Where Brussels Sprout and Acetaminophen, Codeine, Doxylamine 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

#1,201 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Acetaminophen, Codeine, Doxylamine
Steady interest

#1,548 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
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 Acetaminophen, Codeine, Doxylamine, 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 Acetaminophen, Codeine, Doxylamine supplement interactions › Every supplement checked against Acetaminophen, Codeine, Doxylamine, 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 Brussels Sprout and Acetaminophen, Codeine, Doxylamine Together: Common Questions

Can you take Brussels Sprout with Acetaminophen, Codeine, Doxylamine?
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 3 interactions listed for Brussels Sprout and Acetaminophen, Codeine, Doxylamine?
Acetaminophen, Codeine, Doxylamine belongs to more than one drug category, and Brussels Sprout 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 Brussels Sprout and Acetaminophen, Codeine, Doxylamine 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

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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.