Drug & supplement interaction

Delta-9-tetrahydrocannabinol (thc) + 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 Delta-9-tetrahydrocannabinol (thc) can interact with; the most serious is rated moderate. Theoretically, THC 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

Delta-9-tetrahydrocannabinol (thc) and Carbamazepine

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

Why Are There 4 Interactions?

Delta-9-tetrahydrocannabinol (thc) interacts with whole categories of medication. Carbamazepine falls into 4 of those categories, so it can interact with Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc) interacts with.

Theoretically, THC might have additive effects if used with other CNS depressants.
Cannabis containing THC can have CNS depressant effects. Combining THC with other CNS depressants might result in additive or synergistic 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

Here's the simple version: both THC and carbamazepine can slow down your brain and nervous system. Carbamazepine already tends to make people feel drowsy, dizzy, or a little foggy, especially when you first start it or after a dose increase. Adding THC on top of that could stack those effects, so you might feel sleepier, more lightheaded, or more unsteady on your feet than usual.

I want to be honest about the evidence here. This is a theoretical concern based on how each one works, not something proven by strong studies, so it doesn't mean trouble is guaranteed. Still, the combo could affect your thinking, coordination, and driving. Please don't change anything 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. 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) INDUCERS

2 of 4

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

Theoretically, CYP3A4 inducers might reduce the levels and clinical effects of THC.
THC 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 gist for this pairing. Carbamazepine is a strong inducer, meaning it revs up the liver enzyme called CYP3A4. THC happens to be broken down by that same enzyme. So if you're taking carbamazepine, your body may clear THC faster, which could leave you with less of THC's effect than you'd expect. In short, carbamazepine isn't building THC up, it's likely thinning it out.

I'll be honest: this is a theoretical interaction based on how the enzyme works, not on solid human studies, so don't lose sleep over it. The bigger thing is your carbamazepine itself, since it's a finicky drug for seizures and mood. Please loop in your doctor or pharmacist before mixing 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.
Moderate

CYTOCHROME P450 2C9 (CYP2C9) INDUCERS

3 of 4

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

Theoretically, drugs that are CYP2C9 inducers might decrease the levels and clinical effects of THC.
THC 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 gist for this pairing. Carbamazepine is a strong enzyme booster (inducer), and one of the enzymes it speeds up is CYP2C9, which happens to help break down THC. So the concern runs in one direction: carbamazepine may cause your body to clear THC faster, which could make the THC feel weaker or wear off sooner. Carbamazepine itself isn't likely to be changed here.

I want to be honest about how solid this is. This interaction is theoretical, based on how the enzymes work on paper rather than real patient studies. If you're using THC and also take carbamazepine for seizures, pain, or mood, don't change anything on your own. Just loop in 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. Product information for Marinol. AbbVie. North Chicago, IL 60064. August 2017. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/018651s029lbl.pdf.
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

4 of 4

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

Theoretically, THC may increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that cannabis containing THC might modestly inhibit the activity of CYP3A4 enzymes, which might decrease the metabolism of CYP3A4 substrates. It is unclear if this effect is due to THC, other constituents, or the combination. In vitro research also shows that cannabis extracts containing THC modestly inhibit the CYP3A4 metabolism of testosterone; extracts providing the specific cannabinoids cannabidiol (CBD) or cannabigerol (CBG) alone had stronger inhibitory effects than extracts containing both THC and CBD. Conversely, a crossover clinical study in healthy adults shows that oral THC does not inhibit CYP3A4.
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 gist for carbamazepine (Tegretol and similar). Your body clears this seizure and nerve-pain medicine partly through a liver enzyme called CYP3A4. In test-tube studies, THC from cannabis seemed to slow that enzyme down a little. In theory, that could let carbamazepine build up slightly, which might mean more dizziness, drowsiness, unsteadiness, blurred or double vision, or nausea.

That said, I wouldn't lose sleep over it. This is graded as a minor and unlikely interaction based only on lab data, and one human study of oral THC showed no real effect on this enzyme. Still, carbamazepine has a narrow safe range, so even small shifts can matter. If you're using THC in any form, it's worth a quick chat with your pharmacist or doctor.

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
  3. 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

Delta-9-tetrahydrocannabinol (thc) Also Interacts With Other Medications

Delta-9-tetrahydrocannabinol (thc) has 761 moderate, 336 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.

Moderate 761 Minor 336 No known interaction 1,733 (incl. Carbamazepine)
Taking anything else?

Check Another of Your Medications Against Delta-9-tetrahydrocannabinol (thc)

Covers the 2,830 medications we’ve checked against Delta-9-tetrahydrocannabinol (thc). Pick one to open its full report.

From our Q&A

Questions About Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc) 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

How much people look this up

Where Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc)
Top half

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

29 days ago today
Medication Carbamazepine
Top 25%

#521 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 Delta-9-tetrahydrocannabinol (thc)

What is Delta-9-tetrahydrocannabinol (thc)?

Delta-9-tetrahydrocannabinol (thc)
  • Chronic or nerve pain
  • Nausea and vomiting from chemotherapy
  • Appetite loss and weight loss
  • Muscle spasticity
  • Sleep problems
  • Anxiety and stress

THC is the main mind-altering compound in cannabis and is best known for causing a 'high.' A prescription form (dronabinol) is approved for chemotherapy-related nausea and appetite loss, but for most other uses the evidence is mixed or limited, and THC can impair thinking and driving. It should be avoided in pregnancy and breastfeeding and used only with medical guidance.

Read the full Delta-9-tetrahydrocannabinol (thc) 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 & Delta-9-tetrahydrocannabinol (thc)

Browse every other medication we’ve checked against Delta-9-tetrahydrocannabinol (thc) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
761Moderate
336Minor
1,732No known interaction
761 Moderate 336 Minor 1,732 No interaction
Moderate

761 interactions

Showing 60 of 761 moderate interactions — see all 761 on the Delta-9-tetrahydrocannabinol (thc) page.

Minor

336 interactions

Showing 60 of 336 minor interactions — see all 336 on the Delta-9-tetrahydrocannabinol (thc) page.

No interaction 1,732 drugs checked — show the list

We also checked Delta-9-tetrahydrocannabinol (thc) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,732 medications checked with no known interaction — see the full Delta-9-tetrahydrocannabinol (thc) list.

See the full Delta-9-tetrahydrocannabinol (thc) 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
Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc) and Carbamazepine Together: Common Questions

Can you take Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc) and Carbamazepine?
Carbamazepine belongs to more than one drug category, and Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc) 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 Delta-9-tetrahydrocannabinol (thc)?

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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.