Drug & supplement interaction

Kratom + 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 4 drug categories that Kratom can interact with; the most serious is rated moderate. Theoretically, concomitant use might increase the risk for adverse CNS depressant effects.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions4
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Kratom and Aspirin, Butalbital, Caffeine, Codeine Phosphate

These two interact in 4 distinct ways. Each one is explained separately below.

Why Are There 4 Interactions?

Kratom interacts with whole categories of medication. Aspirin, Butalbital, Caffeine, Codeine Phosphate falls into 4 of those categories, so it can interact with Kratom in 4 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CNS DEPRESSANTS

1 of 4

Why this applies to Aspirin, Butalbital, Caffeine, Codeine Phosphate

Aspirin, Butalbital, Caffeine, Codeine Phosphate falls under CNS DEPRESSANTS — the group Kratom interacts with.

Theoretically, concomitant use might increase the risk for adverse CNS depressant effects.
Kratom contains mitragynine, a mu-receptor agonist that may cause respiratory depression. Although results from animal research suggest that mitragynine causes less respiratory depression than the CNS depressant codeine, fatalities have been reported for patients who ingested a combination of kratom and O-desmethyltramadol, another mu-receptor agonist. Additionally, observational research suggests that adverse effects such as drowsiness and coma are more likely to occur in individuals taking kratom in combination with agents such as opioids and sedatives. Theoretically, ingesting kratom along with other CNS depressants can increase the risk of adverse effects, including drowsiness, coma, and/or severe or fatal respiratory depression.
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 something worth knowing about Fiorinal with Codeine. This medication already packs two ingredients that calm the nervous system: butalbital, a barbiturate sedative, and codeine, an opioid pain reliever. Kratom acts on the same opioid receptors in your brain, so stacking it on top can pile on the sedation. The real concern is that both can slow your breathing, and combining them may make that worse.

In plain terms, you could end up with heavy drowsiness, foggy thinking, very slow breathing, or in the worst cases something dangerous. This is based on how these substances work and on real reports of harm when kratom is mixed with opioids and sedatives, not just lab theory alone. Please talk with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Backstrom BG, Classon G, Lowenhielm P, Thelander G. [Krypton--new, deadly Internet drug. Since October 2009 have nine young persons died in Sweden]. Lakartidningen 2010;107(50):3196-3197.
  2. Kronstrand R, Roman M, Thelander G, Eriksson A. Unintentional fatal intoxications with mitragynine and O-desmethyltramadol from the herbal blend Krypton. J Anal Toxicol 2011;35(4):242-247. PubMed
  3. Jansen KL, Prast CJ. Ethnopharmacology of kratom and the Mitragyna alkaloids. J Ethnopharmacol 1988;23(1):115-119. PubMed
  4. Davidson C, Cao D, King T, et al. A comparative analysis of kratom exposure cases in Thailand and the United States from 2010-2017. Am J Drug Alcohol Abuse. 2020:1-10. PubMed
Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 4

Aspirin, Butalbital, Caffeine, Codeine Phosphate also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, kratom might increase the levels and clinical effects of drugs metabolized by CYP2D6.
In vitro research suggests that kratom extract inhibits CYP2D6 enzyme activity. However, human research shows that a single low dose of kratom tea 2 grams does not inhibit CYP2D6 activity. However, this kratom dose is lower than what is normally taken for psychoactive effects. In one case report, a 63-year-old male presented with possible serotonin syndrome after taking an unknown dose of kratom for up to 3 months along with serotonergic prescription medications bupropion, buspirone, desvenlafaxine, trazodone, and ziprasidone. It was hypothesized that kratom inhibited CYP2D6-mediated metabolism of buspirone and consequently increased systemic exposure to serotonin. In another case, a 37-year-old male stable for 15 years on amitriptyline presented with anticholinergic symptoms including xerostomia, dry eyes, and constipation, along with mildly elevated bilirubin and liver enzymes after taking progressively higher doses of up to 14 grams of kratom daily for 12 weeks. It was hypothesized that the adverse effects of amitriptyline were precipitated by CYP2D6 inhibition by kratom.
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 wrinkle with this combination product (Fiorinal with Codeine): the codeine part is actually a prodrug. Your body uses a liver enzyme called CYP2D6 to turn codeine into morphine, which is what gives the real pain relief. Lab studies hint that kratom may slow that same enzyme down. If that happens, less codeine gets converted to morphine, so you could get weaker pain relief than expected, while still carrying the codeine's typical side effects like drowsiness or constipation.

I want to be honest that this is mostly theoretical and based on lab data, with low kratom doses showing no real effect in people. Still, kratom acts on opioid receptors itself, so stacking it with an opioid raises the risk of heavy sedation and slowed breathing. Please check in with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kong WM, Chik Z, Ramachandra M, et al. Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay. Molecules. 2011;16(9):7344-7356. PubMed
  2. Eudaley ST, Brooks SP, Hamilton LA. Case Report: Possible Serotonin Syndrome in a Patient Taking Kratom and Multiple Serotonergic Agents. J Pharm Pract 2022. PubMed
  3. Tanna RS, Nguyen JT, Hadi DL, et al. Clinical Assessment of the Drug Interaction Potential of the Psychotropic Natural Product Kratom. Clin Pharmacol Ther 2023;113(6):1315-1325. PubMed
  4. Vanani NB, Stevanovic SG, Stevanovic N. Adverse Drug Interaction Between Kratom and Amitriptyline With Gastrointestinal and Mild Hepatic Effects. Cureus 2023;15(1):e33809. PubMed
Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

3 of 4

Aspirin, Butalbital, Caffeine, Codeine Phosphate also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.

Theoretically, kratom might increase the levels and clinical effects of drugs metabolized by CYP1A2.
In vitro research suggests that kratom extract inhibits the activity of CYP1A2. In one case report, a 63-year-old male presented with possible serotonin syndrome after taking an unknown dose of kratom for up to 3 months along with serotonergic prescription medications bupropion, buspirone, desvenlafaxine, trazodone, and ziprasidone. It was hypothesized that kratom inhibited CYP1A2-mediaed metabolism of ziprasidone which consequently increased systemic exposure to serotonin.
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 the interaction touches: the caffeine. Caffeine is mostly cleared by an enzyme called CYP1A2, and lab studies suggest kratom may slow that enzyme down. If that happens, caffeine could hang around longer and feel stronger, so you might notice more jitteriness, a racing heart, trouble sleeping, or feeling on edge.

I want to be honest about the strength of this: it's theoretical, based on test-tube data, not solid human studies, so it may not amount to much in real life. The bigger concern is actually the codeine and butalbital, since kratom acts on opioid receptors and stacking sedating, opioid-like effects can be dangerous. Please don't change anything on your own. Talk with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kong WM, Chik Z, Ramachandra M, et al. Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay. Molecules. 2011;16(9):7344-7356. PubMed
  2. Eudaley ST, Brooks SP, Hamilton LA. Case Report: Possible Serotonin Syndrome in a Patient Taking Kratom and Multiple Serotonergic Agents. J Pharm Pract 2022. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

4 of 4

Aspirin, Butalbital, Caffeine, Codeine Phosphate also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Kratom might increase the levels and clinical effects of drugs metabolized by CYP3A4.
In vitro research shows that kratom extract inhibits CYP3A4 enzyme activity. A pharmacokinetic study in adults shows that taking kratom tea 2 grams modestly increases the plasma concentration time-curve (AUC) and maximum concentration (Cmax) of CYP3A4 probe midazolam by 40-50% and its CYP3A4-mediated metabolites 18-27%. However, a lack of change in the half-life of midazolam and a simulation of the kratom-midazolam interaction suggest that kratom inhibits CYP3A4 enzymes in the small intestine but not the liver. Additionally, there is one case report of a 27-year-old male who died from neuroleptic malignant-like symptoms after concomitant use of kratom and quetiapine, a CYP3A4 substrate. Although it did not appear that the patient had consumed large quantities of quetiapine, postmortem plasma levels were in the lethal range, indicating possible inhibition of CYP3A4 by kratom. In another case report, a 63-year-old male presented with possible serotonin syndrome after taking an unknown dose of kratom for up to 3 months along with serotonergic prescription medications bupropion, buspirone, desvenlafaxine, trazodone, and ziprasidone. It is hypothesized that CYP3A4 inhibition by kratom reduced metabolism of desvenlafaxine, trazodone, and ziprasidone and consequently increased systemic exposure to serotonin.
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 tricky part with Fiorinal with Codeine: this combo has several pieces, and kratom may affect them in different directions. Kratom appears to mildly block CYP3A4 in your gut, which could nudge up levels of the butalbital (a barbiturate) component, leaving you more sedated, dizzy, or foggy than expected. That stacks on top of kratom's own opioid-like, sleepy effects.

The bigger concern is the codeine. Codeine is a prodrug that needs your body to convert it into morphine, and kratom also pushes on opioid receptors. Layering them raises the risk of heavy sedation, slowed breathing, and dependence. The CYP3A4 part is theoretical, but the opioid-on-opioid piece is real. Please don't combine these without checking with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kong WM, Chik Z, Ramachandra M, et al. Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay. Molecules. 2011;16(9):7344-7356. PubMed
  2. Hughes RL. Fatal combination of mitragynine and quetiapine - a case report with discussion of a potential herb-drug interaction. Forensic Sci Med Pathol. 2019 Mar;15(1):110-113. PubMed
  3. Eudaley ST, Brooks SP, Hamilton LA. Case Report: Possible Serotonin Syndrome in a Patient Taking Kratom and Multiple Serotonergic Agents. J Pharm Pract 2022. PubMed
  4. Tanna RS, Nguyen JT, Hadi DL, et al. Clinical Assessment of the Drug Interaction Potential of the Psychotropic Natural Product Kratom. Clin Pharmacol Ther 2023;113(6):1315-1325. 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

Kratom Also Interacts With Other Medications

Kratom has 982 moderate, 12 minor 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 982 Minor 12 No known interaction 1,836 (incl. Aspirin, Butalbital, Caffeine, Codeine Phosphate)
Taking anything else?

Check Another of Your Medications Against Kratom

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

From our Q&A

Questions About Kratom or Aspirin, Butalbital, Caffeine, Codeine Phosphate

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Kratom or Aspirin, Butalbital, Caffeine, Codeine Phosphate, 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 Aspirin, Butalbital, Caffeine, Codeine Phosphate

This page covers Kratom 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 Kratom as Part of a Dietary Supplement Product? Check It for Interactions

We hold 8 real supplement products containing Kratom, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Kratom. Your product may carry other ingredients that interact with Aspirin, Butalbital, Caffeine, Codeine Phosphate too, on top of Kratom — 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 Kratom 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 Kratom
Top 25%

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

29 days ago today
Medication Aspirin, Butalbital, Caffeine, Codeine Phosphate
Steady interest

#1,941 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 Kratom

What is Kratom?

Kratom
  • Pain relief
  • Opioid withdrawal symptoms
  • Anxiety and stress
  • Low energy or fatigue
  • Mood enhancement

Kratom is a Southeast Asian plant whose leaves act on the brain's opioid receptors and can produce both stimulant-like and opioid-like effects. It is not approved or proven safe by health regulators, carries real risks of dependence and serious harm, and its legal status varies widely. Talk to a pharmacist or doctor before considering it.

Read the full Kratom monograph & all interactions
Keep checking

Other Drugs & Kratom

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

0Major
982Moderate
12Minor
1,835No known interaction
982 Moderate 12 Minor 1,835 No interaction
Moderate

982 interactions

Showing 60 of 982 moderate interactions — see all 982 on the Kratom page.

Minor

12 interactions

No interaction 1,835 drugs checked — show the list

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

Showing the 60 most looked-up of 1,835 medications checked with no known interaction — see the full Kratom list.

See the full Kratom 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
Kratom 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 Kratom and Aspirin, Butalbital, Caffeine, Codeine Phosphate Together: Common Questions

Can you take Kratom 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 4 interactions listed for Kratom and Aspirin, Butalbital, Caffeine, Codeine Phosphate?
Aspirin, Butalbital, Caffeine, Codeine Phosphate belongs to more than one drug category, and Kratom 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 Kratom 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

Still Have a Question About Aspirin, Butalbital, Caffeine, Codeine Phosphate and Kratom?

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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.