Drug & supplement interaction

Anise + 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 2 drug categories that Anise can interact with; the most serious is rated moderate. Theoretically, anise oil might increase the effects and adverse effects of codeine.

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

Anise and Acetaminophen, Codeine, Doxylamine

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

Why Are There 2 Interactions?

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

Moderate

CODEINE

1 of 2

Why this applies to Acetaminophen, Codeine, Doxylamine

Acetaminophen, Codeine, Doxylamine falls under CODEINE — the group Anise interacts with.

Theoretically, anise oil might increase the effects and adverse effects of codeine.
Animal research shows that anise oil increases the analgesic effects of codeine, possibly by inducing its phase I metabolism and increasing conversion to morphine. Whether this interaction occurs in humans is unclear.
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 key thing about your Mersyndol: the codeine part is actually a prodrug. Your body has to convert it into morphine before it does much of anything for pain. So if something speeds up that conversion, you can end up with more morphine effect than expected.

That's what the lab and animal research hints at with anise oil. It may nudge the body to turn more codeine into morphine, which in theory could make this medicine hit harder. Realistically that might mean more drowsiness, dizziness, constipation, nausea, or slowed breathing, especially since doxylamine already makes you sleepy. But honestly, this is only animal data, and we don't know if it happens in people. A cup of anise tea is unlikely to matter; concentrated anise oil is the bigger question mark. Check with me or your doctor before combining them regularly.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Samojlik I, Mijatovic V, Petkovic S, et al. The influence of essential oil of aniseed (Pimpinella anisum, L.) on drug effects on the central nervous system. Fitoterapia 2012;83:1466-73. PubMed
Minor

ACETAMINOPHEN (Tylenol, others)

2 of 2
Theoretically, anise oil might decrease the levels and clinical effects of acetaminophen.
Animal research shows that taking anise oil with acetaminophen decreases peak plasma levels of acetaminophen but does not reduce overall bioavailability. Whether this interaction will occur in humans is unclear.
Severity Minor 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 on combining anise with Mersyndol (which blends acetaminophen, codeine, and the antihistamine doxylamine). The only interaction we have on file is between anise oil and the acetaminophen part, and it's pretty minor. In animal studies, anise oil seemed to slow how quickly acetaminophen showed up in the blood (a lower peak level), but the total amount absorbed didn't really change. In plain terms, your pain relief might come on a touch slower, not weaker overall.

This is theoretical and based on animal research, so I wouldn't lose sleep over it. A cup of anise tea or seeds in your cooking is very unlikely to matter. Concentrated anise essential oil is a different story, so if you use that regularly, just mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Samojlik I, Petkovic S, Stilinovic N, et al. Pharmacokinetic herb-drug interaction between essential oil of aniseed (Pimpinella anisum L., Apiaceae) and acetaminophen and caffeine: A potential risk for clinical practice. Phytother Res 2016;30:253-9.

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

Anise Also Interacts With Other Medications

Anise has 192 moderate, 52 minor 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 192 Minor 52 No known interaction 2,586 (incl. Acetaminophen, Codeine, Doxylamine)
Taking anything else?

Check Another of Your Medications Against Anise

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

Everything else you take

See Every Supplement That Interacts With Acetaminophen, Codeine, Doxylamine

This page covers Anise 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

One more smart check

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

We hold 465 real supplement products containing Anise, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Anise. Your product may carry other ingredients that interact with Acetaminophen, Codeine, Doxylamine too, on top of Anise — 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 Anise 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 Anise
Top half

#381 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 Anise

What is Anise?

Anise
  • Digestive upset and bloating
  • Cough and respiratory complaints
  • Sore throat
  • Menstrual discomfort
  • Flavoring agent

Anise is a fragrant, licorice-flavored seed used for centuries to ease digestion and soothe coughs. Most of its health claims are based on tradition and small or laboratory studies rather than strong human research, so evidence is limited. It is generally safe as a food and tea for most adults, but the concentrated essential oil should be used carefully and avoided in pregnancy.

Read the full Anise monograph & all interactions
Keep checking

Other Drugs & Anise

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

0Major
192Moderate
52Minor
2,585No known interaction
192 Moderate 52 Minor 2,585 No interaction
Moderate

192 interactions

Showing 60 of 192 moderate interactions — see all 192 on the Anise page.

Minor

52 interactions

No interaction 2,585 drugs checked — show the list

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

Showing the 60 most looked-up of 2,585 medications checked with no known interaction — see the full Anise list.

See the full Anise 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
Anise 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 Anise and Acetaminophen, Codeine, Doxylamine Together: Common Questions

Can you take Anise 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 2 interactions listed for Anise and Acetaminophen, Codeine, Doxylamine?
Acetaminophen, Codeine, Doxylamine belongs to more than one drug category, and Anise 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 Anise 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.