Drug & supplement interaction

Delta-9-tetrahydrocannabinol (thc) + Belladona Extract, Phenobarbital

Belladona Extract, Phenobarbital brand name: Chardonna-2.

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

Belladona Extract, Phenobarbital 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 Belladona Extract, Phenobarbital

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. Belladona Extract, Phenobarbital 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 Belladona Extract, Phenobarbital

Belladona Extract, Phenobarbital 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 gist with Chardonna-2: the phenobarbital part is a barbiturate that calms the brain down. THC also has a sedating, mind-slowing side to it. Put the two together and those calming effects can stack up, so you might feel more drowsy, foggy, or lightheaded than you'd expect from either one alone. Driving and anything that needs full focus could feel harder, and the belladonna piece can add its own dry mouth and dizziness on top.

I'll be honest, this is a theoretical concern based on how these things work, not strong real-world proof, so it isn't a reason to panic. Still, since phenobarbital is a potent sedative, it's worth a quick chat with your pharmacist or doctor before combining them.

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

BARBITURATES

2 of 4

Belladona Extract, Phenobarbital also falls under BARBITURATES.

Theoretically, THC might increase the levels and adverse effects of barbiturates.
Some research shows that synthetic THC (dronabinol) increases the elimination half-life of pentobarbital by 4 hours when dosed concomitantly. Also, in animal research, THC potentiated pentobarbital-induced sleep by more than three-fold.
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

Chardonna-2 contains phenobarbital, a barbiturate that calms the nervous system, along with belladonna to ease stomach cramping. The concern here is that THC may slow how quickly your body clears the phenobarbital, letting it linger and build up a bit more than expected. On top of that, both THC and phenobarbital are sedating on their own, so layering them can deepen that effect.

In real life, that could mean feeling extra drowsy, foggy, dizzy, or slowed down, which matters a lot for driving or balance. I'll be honest though: this is based mostly on lab and animal studies, so it's theoretical, not proven in people. Still, please loop in your pharmacist or doctor before combining them so they can keep an eye on the sedation.

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. Kimura T, Takaya M, Usami N, Watanabe K, Yamamoto I. ?9-Tetrahydrocannabinol, a major marijuana component, enhances the anesthetic effect of pentobarbital through the CB1 receptor. Forensic Toxicol. 2019;37(1):207-214. DOI
Moderate

CYTOCHROME P450 3A4 (CYP3A4) INDUCERS

3 of 4

Belladona Extract, Phenobarbital 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 Chardonna-2: it contains phenobarbital, which is a well-known booster (inducer) of the liver enzyme CYP3A4. THC happens to be broken down by that same enzyme. So in theory, taking phenobarbital can speed up how fast your body clears THC, leaving less of it around. The practical result would be weaker THC effects, whether you're using it for symptom relief or recreationally.

I'll be honest, this is a theoretical concern based on how the drugs work, not something proven in studies, so don't lose sleep over it. The bigger real-world issue is that phenobarbital and THC can both cause drowsiness and fuzzy thinking, which can stack up. Please chat with your pharmacist or doctor before combining them.

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

Belladona Extract, Phenobarbital 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 with Chardonna-2: the phenobarbital in it is a classic enzyme 'speed-up' agent, meaning it revs up several liver enzymes including CYP2C9. Since THC is partly broken down by CYP2C9, taking it alongside phenobarbital could clear the THC out of your system a bit faster. In plain terms, your THC may feel weaker or wear off sooner than expected.

I'll be honest, this one is theoretical, based on how these compounds behave in the lab rather than solid human studies, so it may not be a big deal in real life. The bigger thing to watch is the combined drowsiness and foggy thinking, since both phenobarbital and THC can sedate you. Please don't change anything on your own, just loop in 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.

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 762 moderate, 336 minor known drug interactions in our database — the Belladona Extract, Phenobarbital one above is among them. If you take anything else, check it against the full list below.

Moderate 762 Minor 336 No known interaction 1,732 (incl. Belladona Extract, Phenobarbital)
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.

Everything else you take

See Every Supplement That Interacts With Belladona Extract, Phenobarbital

This page covers Delta-9-tetrahydrocannabinol (thc) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Belladona Extract, Phenobarbital page lists 141 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 Kava (major).

By severity: 8 major · 115 moderate · 18 minor.

From our pharmacist’s overview on the Belladona Extract, Phenobarbital page

“Chardonna-2 pairs belladonna with phenobarbital, a sedating barbiturate, so anyone taking it for stomach or bowel spasms is already on something that slows the brain down. That is why 78 of the 141 supplement interactions on file involve added sedation, and why this list warrants real vigilance rather than a quick skim.”

Reviewed by 2 · Jul 18, 2026

Open the Belladona Extract, Phenobarbital interaction page

How much people look this up

Where Delta-9-tetrahydrocannabinol (thc) and Belladona Extract, Phenobarbital 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

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

29 days ago today
Medication Belladona Extract, Phenobarbital
Top half

#909 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
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
762Moderate
336Minor
1,731No known interaction
762 Moderate 336 Minor 1,731 No interaction
Moderate

762 interactions

Showing 60 of 762 moderate interactions — see all 762 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 1,731 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 1,731 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 Belladona Extract, Phenobarbital, 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 Belladona Extract, Phenobarbital supplement interactions › Every supplement checked against Belladona Extract, Phenobarbital, 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 Delta-9-tetrahydrocannabinol (thc) and Belladona Extract, Phenobarbital Together: Common Questions

Can you take Delta-9-tetrahydrocannabinol (thc) with Belladona Extract, Phenobarbital?
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 Belladona Extract, Phenobarbital?
Belladona Extract, Phenobarbital 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 Belladona Extract, Phenobarbital 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

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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.