Drug & supplement interaction

Cannabis + Carbamazepine

Carbamazepine brand names: Tegretol, Tegretol XR, Equetro, Carbatrol, Carnexiv.

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

Carbamazepine falls into 4 drug categories that Cannabis can interact with; the most serious is rated moderate. Theoretically, cannabis might have additive effects if used with other CNS depressants.

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

Cannabis and Carbamazepine

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

Why Are There 4 Interactions?

Cannabis interacts with whole categories of medication. Carbamazepine falls into 4 of those categories, so it can interact with Cannabis 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 Carbamazepine

Carbamazepine falls under CNS DEPRESSANTS — the group Cannabis interacts with.

Theoretically, cannabis might have additive effects if used with other CNS depressants.
Cannabis can have CNS depressant effects. Combining cannabis with other CNS depressants might result in additive or synergistic effects. A small clinical trial in healthy adults shows that inhaling a high-grade cannabis (Bedrocan International B.V., Veendam, The Netherlands) 100 mg, containing delta-9-tetrahydrocannabinol 21.8% and cannabinol 0.1%, modestly increases subjective feelings of sedation when compared with cannabis alone.
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 simple version: both cannabis and carbamazepine (Tegretol) can slow down your central nervous system. When you put them together, those calming, sedating effects can stack up. That means you might feel more drowsy, dizzy, foggy, or unsteady on your feet than you would with either one alone. Carbamazepine already tends to cause sleepiness and balance problems, so cannabis could make that more noticeable.

I want to be honest about the evidence here: this is mostly a theoretical concern based on how these substances act, not a strong red flag. Still, since trouble with coordination and alertness can affect driving and falls, it's worth a quick chat with your pharmacist or doctor before combining them, especially while your dose is being adjusted.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Marinol Prescribing Information. Solvay Pharmaceuticals, Rev March 2008. Available at: http://www.solvaypharmaceuticals-us.com/static/wma/pdf/1/3/2/5/0/004InsertText500012RevMar2008.pdf (Accessed 2 July 2009).
  2. Hollister, L. E. Interactions of cannabis with other drugs in man. NIDA Res.Monogr 1986;68:110-116. DOI
  3. van Dam CJ, van der Schrier R, van Velzen M, et al. Inhaled Delta(9)-tetrahydrocannabinol does not enhance oxycodone-induced respiratory depression: randomised controlled trial in healthy volunteers. Br J Anaesth 2023;130(4):485-493.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 4

Carbamazepine 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

Here's the gist: your body uses an enzyme called CYP3A4 to break down carbamazepine. Lab studies suggest cannabis (especially CBD-heavy products) may slow that enzyme down a bit. In theory, that could let carbamazepine build up in your blood, which might mean more side effects like dizziness, drowsiness, blurred or double vision, unsteadiness, or nausea.

I want to be honest about the strength of this, though. It comes from test-tube research, not real patient studies, so it's more of a theoretical concern than a proven one. Carbamazepine is also a drug where blood levels really matter, so even small shifts are worth watching. Please don't start, stop, or change anything on your own. Just loop in your doctor or pharmacist first, especially since cannabis can add to the drowsiness on its own.

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 3A4 (CYP3A4) INDUCERS

3 of 4

Carbamazepine also falls under CYTOCHROME P450 3A4 (CYP3A4) INDUCERS.

Theoretically, CYP3A4 inducers might reduce the levels and clinical 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

Here's the thing to understand about this pairing: it's really carbamazepine acting on the cannabis, not the other way around. Carbamazepine is a strong CYP3A4 inducer, meaning it revs up the liver enzyme that breaks down THC, one of cannabis's main active compounds. So in theory, if you're taking carbamazepine regularly, your body may clear THC faster and you could feel less effect from the same amount of cannabis.

I want to be honest that this is theoretical, based on how these substances are processed rather than solid human studies. It's also worth knowing carbamazepine itself can make you drowsy or dizzy, and adding cannabis may stack onto that. Please don't change your dose of either one on your own. Have a quick chat with your pharmacist or doctor first.

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 2C9 (CYP2C9) INDUCERS

4 of 4

Carbamazepine also falls under CYTOCHROME P450 2C9 (CYP2C9) INDUCERS.

Theoretically, drugs that are CYP2C9 inducers might decrease the effects of cannabis.
Delta-9-tetrahydrocannabinol (THC), an active constituent of cannabis, is a substrate of CYP2C9 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

Here's the key thing to know: in this pairing, it's the cannabis that gets affected, not your carbamazepine. Carbamazepine is a strong 'inducer,' meaning it revs up certain liver enzymes (including CYP2C9). Since THC, the active part of cannabis that causes the high, is broken down by that same enzyme, taking carbamazepine could speed up how fast your body clears THC. The practical result? Cannabis may feel weaker or wear off faster than you'd expect.

I'll be honest with you, this one is theoretical, based on how these compounds behave in the lab rather than strong patient studies, so don't be alarmed. Carbamazepine itself isn't expected to become more or less effective from this. Still, since carbamazepine needs steady levels to control seizures or nerve pain, it's worth a quick chat with your doctor or pharmacist before combining the two.

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.

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 Carbamazepine 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. Carbamazepine)
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 Carbamazepine

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 Carbamazepine, 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 Carbamazepine

This page covers Cannabis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carbamazepine page lists 284 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: 12 major · 235 moderate · 37 minor.

From our pharmacist’s overview on the Carbamazepine page

“Carbamazepine (Tegretol, Carbatrol, Equetro) only controls seizures and mood episodes when its blood level stays inside a tight window, and 284 supplement and herbal ingredients on file can disturb that balance, 12 of them rated major. Grapefruit can push carbamazepine levels up, St.”

Reviewed by 2 · Jul 18, 2026

Open the Carbamazepine 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 Carbamazepine 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 Carbamazepine 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%

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

29 days ago today
Medication Carbamazepine
Top 25%

#397 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
Medication

About Carbamazepine

What Is Carbamazepine Used For?

Brand names: Tegretol, Tegretol XR, Equetro, Carbatrol, Carnexiv

Carbamazepine is used to treat certain types of seizures — including partial seizures, generalized tonic-clonic (grand mal) seizures, and mixed seizure patterns. It works best for those specific seizure types; it does not appear to control absence (petit mal) seizures.

It is also prescribed to relieve the intense facial pain of trigeminal neuralgia — a nerve condition that causes sudden, severe pain along the face. It is not a general painkiller and shouldn't be used for ordinary aches and pains.

See full Carbamazepine drug information
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 Carbamazepine, 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 Carbamazepine supplement interactions › Every supplement checked against Carbamazepine, ranked by severity Carbamazepine drug information › The full plain-English guide to this medication 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 Carbamazepine Together: Common Questions

Can you take Cannabis with Carbamazepine?
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 Cannabis and Carbamazepine?
Carbamazepine 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 Carbamazepine 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 Carbamazepine 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.