Drug & supplement interaction

Parsley + Acetaminophen, Aspirin, Caffeine

Acetaminophen, Aspirin, Caffeine brand names: Excedrin Migraine, Excedrin, Excedrin Extra Strength.

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

Acetaminophen, Aspirin, Caffeine falls into 3 drug categories that Parsley can interact with; the most serious is rated moderate. Theoretically, parsley might increase serum levels of CYP1A2 substrates.

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

Parsley and Acetaminophen, Aspirin, Caffeine

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

Why Are There 3 Interactions?

Parsley interacts with whole categories of medication. Acetaminophen, Aspirin, Caffeine falls into 3 of those categories, so it can interact with Parsley 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, Aspirin, Caffeine

Acetaminophen, Aspirin, Caffeine falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Parsley interacts with.

Theoretically, parsley might increase serum levels of CYP1A2 substrates.
Laboratory research suggests that parsley can inhibit CYP1A2.
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 piece that matters for products like Excedrin: the caffeine in that combo is cleared by a liver enzyme called CYP1A2. Lab studies hint that parsley may slow that enzyme down. If that happens, caffeine could hang around longer than usual, so you might feel more of its effects, things like jitteriness, a racing or pounding heart, trouble sleeping, or feeling wired.

I want to be honest about how soft this is. It's theoretical, based on lab work, not real people, and the aspirin and acetaminophen parts aren't the concern here. Eating parsley as a garnish or in a salad is very unlikely to matter. Concentrated parsley supplements or extracts are a different story, so if you use those regularly, check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Peterson, S., Lampe, J. W., Bammler, T. K., Gross-Steinmeyer, K., and Eaton, D. L. Apiaceous vegetable constituents inhibit human cytochrome P-450 1A2 (hCYP1A2) activity and hCYP1A2-mediated mutagenicity of aflatoxin B1. Food Chem.Toxicol. 2006;44(9):147 PubMed
Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

2 of 3

Acetaminophen, Aspirin, Caffeine also falls under ANTICOAGULANT/ANTIPLATELET DRUGS.

Theoretically, parsley might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
Animal research suggests that parsley has antiplatelet 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

The medicine you're asking about (Excedrin Migraine) contains aspirin, which already thins the blood a bit by making platelets less sticky. Parsley, at least in animal studies, seems to have a mild similar effect. So the concern here is that pairing them could nudge your bleeding risk up a little. In real life that might show up as easier bruising, a nosebleed that takes longer to stop, or some stomach upset or irritation from the aspirin itself.

Honestly, this is a theoretical worry based only on lab and animal data, not strong human evidence. Eating parsley as a food garnish is very unlikely to matter. Concentrated parsley supplements, seed extracts, or the essential oil are where I'd be more cautious. If you use those regularly, just check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gadi, D., Bnouham, M., Aziz, M., Ziyyat, A., Legssyer, A., Legrand, C., Lafeve, F. F., and Mekhfi, H. Parsley extract inhibits in vitro and ex vivo platelet aggregation and prolongs bleeding time in rats. J Ethnopharmacol 8-17-2009;125(1):170-174. PubMed
Minor

ASPIRIN

3 of 3

Acetaminophen, Aspirin, Caffeine also falls under ASPIRIN.

Theoretically, aspirin might increase the severity of allergic reactions to parsley.
In one case, severe urticaria and swelling were reported after taking aspirin with parsley in an individual with a known mild parsley allergy.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the honest scoop on this one. Your Excedrin product contains aspirin, and the only concern on file with parsley isn't really about how your body breaks the medicine down. It's about allergies. Aspirin can sometimes ramp up an allergic reaction you'd already have to something else, and there's a single reported case where someone with a known mild parsley allergy got hives and swelling after combining the two.

So this is theoretical and very unlikely, based on just one anecdote. If you don't have a parsley allergy, eating parsley in normal food amounts alongside Excedrin shouldn't cause trouble. If you do react to parsley, mention it to your pharmacist or doctor before leaning on concentrated parsley supplements.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Eberhard P, Gall HM, Muller I, Moller R. Dramatic augmentation of a food allergy by acetylsalicylic acid. J Allergy Clin Immunol 2000;105:844 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

Parsley Also Interacts With Other Medications

Parsley has 442 moderate known drug interactions in our database — the Acetaminophen, Aspirin, Caffeine one above is among them. If you take anything else, check it against the full list below.

Moderate 442 No known interaction 2,388 (incl. Acetaminophen, Aspirin, Caffeine)
Taking anything else?

Check Another of Your Medications Against Parsley

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

Everything else you take

See Every Supplement That Interacts With Acetaminophen, Aspirin, Caffeine

This page covers Parsley only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Aspirin, Caffeine page lists 371 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Danshen (major) and Ephedra (major).

By severity: 13 major · 312 moderate · 46 minor.

From our pharmacist’s overview on the Acetaminophen, Aspirin, Caffeine page

“Excedrin (acetaminophen, aspirin, and caffeine) packs three drugs into one tablet, which multiplies the ways supplements can collide with it, so treat this list with real care. Most entries involve the aspirin: hundreds of herbs add to its blood-thinning effect and raise bleeding risk, and even beer or wine earns a major rating for sto…”

Reviewed by 2 · Jul 18, 2026

Open the Acetaminophen, Aspirin, Caffeine interaction page

One more smart check

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

We hold 3,292 real supplement products containing Parsley, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Parsley. Your product may carry other ingredients that interact with Acetaminophen, Aspirin, Caffeine too, on top of Parsley — 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 Parsley and Acetaminophen, Aspirin, Caffeine 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 Parsley
Top 10%

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

29 days ago today
Medication Acetaminophen, Aspirin, Caffeine
Top 25%

#383 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 Parsley

What is Parsley?

Parsley
  • Water retention and bloating
  • Urinary and bladder support
  • Digestive upset
  • Freshening breath
  • Source of vitamins and antioxidants

Parsley is a popular culinary herb that is safe to eat in normal food amounts and is a good source of vitamins K and C. It is traditionally used as a diuretic and for digestion, but solid human evidence for medicinal benefits is limited. Concentrated supplements, seed extracts, and the essential oil are much stronger than food and should be used cautiously, especially during pregnancy.

Read the full Parsley monograph & all interactions
Keep checking

Other Drugs & Parsley

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

0Major
442Moderate
0Minor
2,387No known interaction
442 Moderate 2,387 No interaction
Moderate

442 interactions

Showing 60 of 442 moderate interactions — see all 442 on the Parsley page.

No interaction 2,387 drugs checked — show the list

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

Showing the 60 most looked-up of 2,387 medications checked with no known interaction — see the full Parsley list.

See the full Parsley interactions page
See every supplement checked against Acetaminophen, Aspirin, Caffeine, 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
Parsley monograph › Uses, safety, and every drug interaction in one place Acetaminophen, Aspirin, Caffeine supplement interactions › Every supplement checked against Acetaminophen, Aspirin, Caffeine, 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 Parsley and Acetaminophen, Aspirin, Caffeine Together: Common Questions

Can you take Parsley with Acetaminophen, Aspirin, Caffeine?
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 Parsley and Acetaminophen, Aspirin, Caffeine?
Acetaminophen, Aspirin, Caffeine belongs to more than one drug category, and Parsley 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 Parsley and Acetaminophen, Aspirin, Caffeine 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.