Drug & supplement interaction

Cannabis + Diazepam

Diazepam brand names: Valium, Valium injection, Diastat AcuDial, Valtoco.

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

Diazepam 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 Diazepam

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. Diazepam 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 Diazepam

Diazepam 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 Valium (diazepam) calm down activity in your brain. When you put them together, those calming effects can stack on top of each other. That means you may feel sleepier, foggier, or more lightheaded than you'd expect from either one alone. Your coordination and reaction time can take a hit too, which matters a lot for driving or anything that needs focus.

I'll be honest with you, this concern is mostly based on how these substances work rather than hard proof. One small study found cannabis added only a modest bump in sedation. Still, since both can slow you down, it's worth a quick chat with your doctor or pharmacist, especially if you notice extra drowsiness.

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 2C9 (CYP2C9) SUBSTRATES

2 of 4

Diazepam also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, cannabis might increase the levels and adverse effects of CYP2C9 substrates.
In vitro research shows that the cannabis constituents delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol moderately inhibit the CYP2C9-mediated 7-hydroxylation of S-warfarin in a concentration-dependent manner. In vitro research also shows that cannabis extracts modestly inhibit the CYP2C9 metabolism of tolbutamide; 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 liver enzymes (including one called CYP2C9) to break down diazepam and clear it out. Lab studies suggest the compounds in cannabis, mainly THC and CBD, can slow that enzyme down a bit. In theory, that means diazepam could hang around longer and build up, leading to stronger and longer-lasting effects like extra drowsiness, dizziness, confusion, or feeling unsteady on your feet.

I want to be honest about the evidence though: this comes from test-tube research, not real people, so it's more of a theoretical caution than a proven problem. There's also a real overlap concern, since both cannabis and diazepam are sedating, so together they can make you sleepier and slow your reactions. Please loop in your doctor or pharmacist before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Damkier P, Lassen D, Christensen MMH, Madsen KG, Hellfritzsch M, Pottegård A. Interaction between warfarin and cannabis. Basic Clin Pharmacol Toxicol. 2019;124(1):28-31. 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) SUBSTRATES

3 of 4

Diazepam 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 partly relies on a liver enzyme called CYP3A4 to clear diazepam (Valium) out of your system. Lab studies suggest that compounds in cannabis, especially CBD and CBG, can slow that enzyme down a bit. If that happens in real life, diazepam could hang around longer and build up, meaning stronger and longer effects than you expect.

For diazepam that could look like extra drowsiness, dizziness, trouble concentrating, or feeling unsteady. On top of that, cannabis and diazepam both calm the brain, so combining them can pile on sedation by itself. The actual enzyme data here is only from test-tube research, so this is more theoretical than proven, but it's worth a quick chat with your pharmacist or doctor before mixing the two.

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

4 of 4

Diazepam 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

Here's the gist for Valium (diazepam): your liver uses an enzyme called CYP2C19 to help break it down. The CBD found in cannabis can slow that enzyme down. When that happens, diazepam may clear out of your body more slowly and build up a bit higher than usual.

What that can look like in real life is more sedation, feeling extra drowsy or foggy, dizziness, poor balance, or trouble concentrating. Keep in mind both diazepam and cannabis are already calming on their own, so stacking them can add up. To be fair, this particular concern is mostly theoretical, based on how these chemicals behave rather than strong human studies with diazepam specifically. Still, please run it by your doctor or pharmacist before combining them, and don't change your dose on your 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 Diazepam 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. Diazepam)
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 Diazepam

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 Diazepam, 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 Diazepam

This page covers Cannabis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Diazepam page lists 244 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), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Grapefruit (major).

By severity: 9 major · 191 moderate · 44 minor.

Open the Diazepam 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 Diazepam 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 Diazepam 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 Diazepam
Top 5%

#128 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 Diazepam

What Is Diazepam Used For?

Brand names: Valium, Valium injection, Diastat AcuDial, Valtoco

  • Diazepam is used to relieve anxiety and to control agitation caused by alcohol withdrawal. It is also used along with other medications to control muscle spasms and spasticity caused by certain neurological disorders such as cerebral palsy (condition that causes difficulty with movement and balance), paraplegia (inability to move parts of the body), athetosis (abnormal muscle contractions), and stiff-man syndrome (a rare disorder with muscle rigidity and stiffness). Diazepam is also used along with other medications to control seizures. Diazepam is in a class of medications called benzodiazepines. It works by calming abnormal overactivity in the brain.

See full Diazepam 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 Diazepam, 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 Diazepam supplement interactions › Every supplement checked against Diazepam, ranked by severity Diazepam 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 Diazepam Together: Common Questions

Can you take Cannabis with Diazepam?
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 Diazepam?
Diazepam 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 Diazepam 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 Diazepam 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.