Drug & supplement interaction

Cannabis + Flupenthixol

Flupenthixol brand name: Fluanxol.

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

Flupenthixol falls into 2 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
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Cannabis and Flupenthixol

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Cannabis interacts with whole categories of medication. Flupenthixol falls into 2 of those categories, so it can interact with Cannabis in 2 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 2

Why this applies to Flupenthixol

Flupenthixol 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

Flupenthixol is an antipsychotic that can already make some people feel drowsy, slowed down, or a bit foggy. Cannabis works on its own receptors in the brain, but the practical concern here is that it can add to that sedating effect. Put them together and you may feel sleepier, more lightheaded, slower to react, or unsteady on your feet than with either one alone.

Keep in mind this is a theoretical interaction based on how both act in the body, not a strong proven danger, and one small study only showed a modest bump in sedation. Still, it's worth being cautious, especially with driving or stairs. 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.
Minor

ANTIPSYCHOTIC DRUGS

2 of 2

Flupenthixol also falls under ANTIPSYCHOTIC DRUGS.

Cannabis does not seem to affect blood levels or effects of some antipsychotic drugs.
Human research shows that cannabis use does not affect blood levels or clinical effects of amisulpride, aripiprazole, or olanzapine in patients with schizophrenia and related disorders.
Severity Minor Likelihood Unlikely Evidence B

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 reassuring part: in studies looking at antipsychotics like olanzapine, aripiprazole, and amisulpride, cannabis did not meaningfully change the blood levels or the way those medicines worked. Flupenthixol falls in the same family, so we'd expect a similar story. This isn't a case where cannabis blocks or speeds up how your body clears the drug.

That said, I'd still raise it with your doctor. Cannabis (especially THC) can cause drowsiness, dizziness, and foggy thinking, and Flupenthixol can do the same, so stacking them may leave you more sedated or unsteady. There's also a real concern that cannabis can worsen some psychotic symptoms it's meant to treat. The drug-level interaction looks minor, but the combined effects are worth a quick chat.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Alisauskiene R, Johnsen E, Gjestad R, et al. Does drug use affect the efficacy of amisulpride, aripiprazole and olanzapine in patients with schizophrenia spectrum disorders? Results from a pragmatic, randomised study. Gen Hosp Psychiatry 2023;83:185-193. 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

Cannabis Also Interacts With Other Medications

Cannabis has 2 major, 1,108 moderate, 25 minor known drug interactions in our database — the Flupenthixol 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. Flupenthixol)
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 Flupenthixol

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 Flupenthixol, 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 Flupenthixol

This page covers Cannabis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Flupenthixol page lists 205 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 15 major · 178 moderate · 12 minor.

Open the Flupenthixol 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 Flupenthixol 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 Flupenthixol 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%

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

29 days ago today
Medication Flupenthixol
Top 25%

#529 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 Flupenthixol, 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 Flupenthixol supplement interactions › Every supplement checked against Flupenthixol, 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 Flupenthixol Together: Common Questions

Can you take Cannabis with Flupenthixol?
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 2 interactions listed for Cannabis and Flupenthixol?
Flupenthixol 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 Flupenthixol 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 Flupenthixol 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.