Drug & supplement interaction

Parsley + Aspirin, Butalbital, Caffeine, Codeine Phosphate

Aspirin, Butalbital, Caffeine, Codeine Phosphate brand name: Fiorinal w/ Codeine.

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

Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate

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. Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate

Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 of this combo pill that matters most for parsley: the caffeine in Fiorinal with Codeine is cleared by a liver enzyme called CYP1A2. Lab studies hint that concentrated parsley might slow that enzyme down, which could let caffeine linger a bit longer than usual. In real life that might show up as feeling jittery, a racing heart, trouble sleeping, or an upset stomach.

I want to be honest that this is theoretical, based only on test-tube research, not on people. Everyday parsley on your plate is very unlikely to do anything. Larger amounts from seed extracts, oils, or supplement capsules are where I'd be more cautious. If you use concentrated parsley regularly, just mention it to your pharmacist or doctor so they can keep an eye on things.

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

Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 piece of this combo pill that matters here is the aspirin. Aspirin already thins the blood by keeping platelets from clumping together. Lab and animal studies hint that parsley may have a mild blood-thinning effect of its own, so stacking a concentrated parsley supplement on top of aspirin could, in theory, add up to a slightly higher chance of bleeding or bruising. Think easy bruising, nosebleeds, or a cut that takes longer to stop.

I want to be honest: this is theoretical and based only on early lab work, not real human cases. Parsley in normal food amounts (a garnish or a salad) is very unlikely to cause trouble. Concentrated seed extracts or oils are the bigger question. If you take those regularly, just run it by 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
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 picture: this is a very minor, unlikely concern, and it really only matters if you already know you're allergic to parsley. The aspirin in your Fiorinal with Codeine doesn't change how parsley is digested or processed. Instead, the thinking is that aspirin can sometimes make an existing allergic reaction feel worse. This comes from a single reported case, so it's anecdotal at best.

If parsley has never bothered you, eating it in normal food amounts is no reason to worry. But if you do have a known parsley allergy and notice hives, itching, or any swelling after a meal seasoned with it, mention that to your pharmacist or doctor. They can help you sort out what's safe for you.

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 Aspirin, Butalbital, Caffeine, Codeine Phosphate 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. Aspirin, Butalbital, Caffeine, Codeine Phosphate)
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 Aspirin, Butalbital, Caffeine, Codeine Phosphate

This page covers Parsley only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Aspirin, Butalbital, Caffeine, Codeine Phosphate page lists 398 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 Danshen (major).

By severity: 17 major · 334 moderate · 47 minor.

From our pharmacist’s overview on the Aspirin, Butalbital, Caffeine, Codeine Phosphate page

“Fiorinal with Codeine packs four active drugs into one capsule, and I would treat its supplement list with genuine wariness rather than a quick skim. The aspirin component is why roughly half of the 398 ingredients on file raise bleeding risk, while the codeine and butalbital explain a second large cluster that deepens sedation, someti…”

Reviewed by 2 · Jul 18, 2026

Open the Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate 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%

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

29 days ago today
Medication Aspirin, Butalbital, Caffeine, Codeine Phosphate
Top 25%

#311 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate, 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate supplement interactions › Every supplement checked against Aspirin, Butalbital, Caffeine, Codeine Phosphate, 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate Together: Common Questions

Can you take Parsley with Aspirin, Butalbital, Caffeine, Codeine Phosphate?
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 Aspirin, Butalbital, Caffeine, Codeine Phosphate?
Aspirin, Butalbital, Caffeine, Codeine Phosphate 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate 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.