Drug & supplement interaction

Cannabis + Lansoprazole, Amoxicillin, Clarithromycin

Lansoprazole, Amoxicillin, Clarithromycin brand name: Prevpac.

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

Lansoprazole, Amoxicillin, Clarithromycin falls into 3 drug categories that Cannabis can interact with; the most serious is rated moderate. Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of cannabis.

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

Cannabis and Lansoprazole, Amoxicillin, Clarithromycin

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

Why Are There 3 Interactions?

Cannabis interacts with whole categories of medication. Lansoprazole, Amoxicillin, Clarithromycin falls into 3 of those categories, so it can interact with Cannabis 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 3A4 (CYP3A4) INHIBITORS

1 of 3

Why this applies to Lansoprazole, Amoxicillin, Clarithromycin

Lansoprazole, Amoxicillin, Clarithromycin falls under CYTOCHROME P450 3A4 (CYP3A4) INHIBITORS — the group Cannabis interacts with.

Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of cannabis.
Delta-9-tetrahydrocannabinol (THC), an active constituent of cannabis, is a substrate of CYP3A4 enzymes.
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

Prevpac is a combo pack with three medicines, and the one that matters here is clarithromycin. Clarithromycin is a known blocker of the liver enzyme CYP3A4, which is the same enzyme that helps break down THC, the active compound in cannabis. When that enzyme is slowed down, THC can clear out of your body more slowly and build up a bit.

In plain terms, that could mean a stronger or longer cannabis effect than usual, things like more drowsiness, dizziness, a faster heartbeat, or feeling more impaired. Keep in mind this is a theoretical concern based on how the drugs work, not something proven in studies, so for most people it stays mild. Still, since this is only a short treatment course, it's worth mentioning to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Product information for Marinol. AbbVie. North Chicago, IL 60064. August 2017. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/018651s029lbl.pdf.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Lansoprazole, Amoxicillin, Clarithromycin also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, cannabis may increase the levels and adverse effects of CYP3A4 substrates.
In vitro research shows that cannabis can inhibit the activity of CYP3A4 enzymes, which might decrease the metabolism of CYP3A4 substrates. In vitro research also shows that cannabis extracts modestly inhibit the CYP3A4 metabolism of testosterone; extracts providing the specific cannabinoids CBD and cannabigerol (CBG) had stronger inhibitory effects than extracts containing THC and CBD.
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

Prevpac is actually a short course of three medicines used to clear an H. pylori stomach infection: lansoprazole (an acid reducer), amoxicillin (an antibiotic), and clarithromycin (another antibiotic). Of these, clarithromycin is the one that the liver's CYP3A4 pathway handles the most. The concern here is that cannabis might gently slow that pathway, which in theory could let a little more clarithromycin build up.

If that happened, you might notice more of clarithromycin's usual nuisances, like an upset stomach, nausea, diarrhea, or a strange metallic taste. I want to be honest, though: this is based only on lab studies, not real patients, so it's a theoretical worry rated as moderate. None of these drugs is a prodrug, so the direction is a possible mild increase, not a loss of effect. Since this is a short, important treatment, just let your pharmacist know if you use cannabis.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pellinen, P., Honkakoski, P., Stenback, F., Niemitz, M., Alhava, E., Pelkonen, O., Lang, M. A., and Pasanen, M. Cocaine N-demethylation and the metabolism-related hepatotoxicity can be prevented by cytochrome P450 3A inhibitors. Eur.J Pharmacol 1-3-1994;2 PubMed
  2. Treyer A, Reinhardt JK, Eigenmann DE, Oufir M, Hamburger M. Phytochemical comparison of medicinal cannabis extracts and study of their CYP-mediated interactions with coumarinic oral anticoagulants. Med Cannabis Cannabinoids. 2023;6(1):21-31. PubMed
Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

3 of 3

Lansoprazole, Amoxicillin, Clarithromycin also falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES.

Cannabis may increase levels of drugs metabolized by CYP2C19.
Research shows that cannabidiol (CBD), a constituent of cannabis, inhibits CYP2C19. In clinical studies and case reports, cannabidiol use resulted in significant increases in the serum levels of topiramate, methadone, citalopram, omeprazole, and N-desmethylclobazam, the primary active metabolite of clobazam. These chemicals are metabolized by CYP2C19. Concomitant use of cannabis with CYP2C19 substrates may increase the risk for adverse effects from these substrates.
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

This Prevpac combo treats H. pylori ulcers, and the piece that interacts with cannabis is the lansoprazole. Lansoprazole is a stomach acid reducer that your liver partly clears using an enzyme called CYP2C19. The CBD in cannabis can slow that enzyme down, so lansoprazole may stick around at higher levels than usual. That could mean a bit more of its typical effects, like headache, stomach upset, or diarrhea.

Honestly, this is a theoretical concern based on how the drugs behave, not strong proof of harm, and you're only taking Prevpac for a couple of weeks. The amoxicillin and clarithromycin aren't affected this way. Still, it's worth a quick chat with your pharmacist or doctor, especially since clarithromycin has plenty of interactions of its own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Harvey DJ. Absorption, distribution, and biotransformation of the cannabinoids. Marijuana and Medicine. 1999;91-103. DOI
  2. Bornheim LM, Everhart ET, Li J, Correia MA. Characterization of cannabidiol-mediated cytochrome P450 inactivation. Biochem Pharmacol 1993;45(6):1323-31. PubMed
  3. Gaston TE, Bebin EM, Cutter GR, Liu Y, Szaflarski JP; UAB CBD Program. Interactions between cannabidiol and commonly used antiepileptic drugs. Epilepsia. 2017 Sep;58(9):1586-92. PubMed
  4. Devinsky O, Marsh E, Friedman D, et la. Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial. Lancet Neurol. 2016 Mar;15(3):270-8.
  5. Geffrey AL, Pollack SF, Bruno PL, Thiele EA. Drug-drug interaction between clobazam and cannabidiol in children with refractory epilepsy. Epilepsia. 2015 Aug;56(8):1246-51. PubMed
  6. Madden K, Tanco K, Bruera E. Clinically Significant Drug-Drug Interaction Between Methadone and Cannabidiol. Pediatrics. 2020;e20193256. PubMed
  7. Anderson LL, Doohan PT, Oldfield L, et al. Citalopram and Cannabidiol: In Vitro and In Vivo Evidence of Pharmacokinetic Interactions Relevant to the Treatment of Anxiety Disorders in Young People. J Clin Psychopharmacol. 2021. PubMed
  8. Nasrin S, Watson CJW, Perez-Paramo YX, Lazarus P. Cannabinoid Metabolites as Inhibitors of Major Hepatic CYP450 Enzymes, with Implications for Cannabis-Drug Interactions. Drug Metab Dispos 2021;49(12):1070-1080. PubMed
  9. Bansal S, Zamarripa CA, Spindle TR, et al. Evaluation of Cytochrome P450-Mediated Cannabinoid-Drug Interactions in Healthy Adult Participants. Clin Pharmacol Ther 2023.

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

Cannabis Also Interacts With Other Medications

Cannabis has 2 major, 1,108 moderate, 25 minor known drug interactions in our database — the Lansoprazole, Amoxicillin, Clarithromycin one above is among them. If you take anything else, check it against the full list below.

Major 2 Moderate 1,108 Minor 25 No known interaction 1,695 (incl. Lansoprazole, Amoxicillin, Clarithromycin)
Taking anything else?

Check Another of Your Medications Against Cannabis

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

From our Q&A

Questions About Cannabis or Lansoprazole, Amoxicillin, Clarithromycin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Cannabis or Lansoprazole, Amoxicillin, Clarithromycin, 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 Lansoprazole, Amoxicillin, Clarithromycin

This page covers Cannabis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Lansoprazole, Amoxicillin, Clarithromycin page lists 246 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Asarabacca (major) and Beer (major).

By severity: 14 major · 185 moderate · 47 minor.

From our pharmacist’s overview on the Lansoprazole, Amoxicillin, Clarithromycin page

“Prevpac pairs lansoprazole with two antibiotics, amoxicillin and clarithromycin, to knock out an H. pylori stomach infection, and I treat its supplement list with genuine caution.”

Reviewed by 2 · Jul 18, 2026

Open the Lansoprazole, Amoxicillin, Clarithromycin interaction page

One more smart check

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

We hold 21 real supplement products containing Cannabis, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cannabis. Your product may carry other ingredients that interact with Lansoprazole, Amoxicillin, Clarithromycin too, on top of Cannabis — 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 Cannabis and Lansoprazole, Amoxicillin, Clarithromycin 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 Cannabis
Top 25%

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

29 days ago today
Medication Lansoprazole, Amoxicillin, Clarithromycin
Top half

#1,140 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 Cannabis

What is Cannabis?

Cannabis
  • Chronic pain
  • Nausea and vomiting from chemotherapy
  • Muscle spasticity (e.g., multiple sclerosis)
  • Anxiety and stress
  • Sleep problems
  • Appetite stimulation

Cannabis contains many active compounds, mainly THC (which causes a 'high') and CBD (which does not). Some uses, such as chemotherapy-related nausea, certain seizure disorders, and muscle spasticity, have meaningful evidence, while many other popular uses are not well proven. It can cause real side effects and impairment, so talk to your doctor or pharmacist and follow your local laws before using it.

Read the full Cannabis monograph & all interactions
Keep checking

Other Drugs & Cannabis

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

2Major
1,108Moderate
25Minor
1,694No known interaction
2 Major 1,108 Moderate 25 Minor 1,694 No interaction
Major

2 interactions

Moderate

1,108 interactions

Showing 60 of 1,108 moderate interactions — see all 1,108 on the Cannabis page.

Minor

25 interactions

No interaction 1,694 drugs checked — show the list

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

Showing the 60 most looked-up of 1,694 medications checked with no known interaction — see the full Cannabis list.

See the full Cannabis interactions page
See every supplement checked against Lansoprazole, Amoxicillin, Clarithromycin, 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
Cannabis monograph › Uses, safety, and every drug interaction in one place Lansoprazole, Amoxicillin, Clarithromycin supplement interactions › Every supplement checked against Lansoprazole, Amoxicillin, Clarithromycin, 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 Cannabis and Lansoprazole, Amoxicillin, Clarithromycin Together: Common Questions

Can you take Cannabis with Lansoprazole, Amoxicillin, Clarithromycin?
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 Cannabis and Lansoprazole, Amoxicillin, Clarithromycin?
Lansoprazole, Amoxicillin, Clarithromycin belongs to more than one drug category, and Cannabis 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 Cannabis and Lansoprazole, Amoxicillin, Clarithromycin 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 Lansoprazole, Amoxicillin, Clarithromycin and Cannabis?

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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.