Drug & supplement interaction

Delta-8-tetrahydrocannabinol (delta-8-thc) + Phenobarbital

Phenobarbital brand names: Phenobarbital, Solfoton, Luminal.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Phenobarbital and Delta-8-tetrahydrocannabinol (delta-8-thc) in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Delta-8-tetrahydrocannabinol (delta-8-thc) at all — not against Phenobarbital, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Delta-8-tetrahydrocannabinol (delta-8-thc) safety at a glance

Delta-8-tetrahydro... overall Use caution It is psychoactive, largely unregulated, and may contain harmful impurities from chemical processing.
Pregnancy Avoid THC compounds can cross the placenta and may harm fetal development; avoid use.
Breastfeeding Avoid THC passes into breast milk and may affect the infant; avoid use.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Phenobarbital and Delta-8-tetrahydrocannabinol (delta-8-thc)? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 2 of them are worth acting on rather than waiting out — marked below.

  • A slow heartbeat Worth acting on Additional detail

    Delta-8-tetrahydrocannabinol (delta-8-thc)

    “Based on statistics from the American Association of Poison Control Centers, hospitalization occurred in 18% of 661 reported exposures to delta-8-THC in the first 7 months of 2021. In the 8-month period ending in July 2021, 14 of 22 cases reported to the US FDA presented to the hospital for adverse effects related to delta-8-THC-containing products.”

    Delta-8-tetrahydrocannabinol (delta-8-thc) · Natural Medicines adverse-effect record, reported in hypotension.

    3 sources cited
    1. 106108. Centers for Disease Control and Prevention (CDC). Increases in availability of cannabis products containing delta-8 THC and reported cases of adverse events. September 2021. https://emergency.cdc.gov/han/2021/han00451.asp. Accessed October 2, 2021.
    2. 106107. US Food and Drug Administration (FDA). 5 things to know about delta-8 tetrahydrocannabinol - delta-8 THC. September 2021. https://www.fda.gov/consumers/consumer-updates/5-things-know-about-delta-8-tetrahydrocannabinol-delta-8-thc. Accessed October 2, 2021
    3. 107322. Akpunonu P, Baum RA, Reckers A, et al. Sedation and Acute Encephalopathy in a Pediatric Patient Following Ingestion of Delta-8-Tetrahydrocannabinol Gummies. Am J Case Rep 2021;22:e933488. PubMed

    Phenobarbital

    Listed in the ADVERSE REACTIONS section of the FDA label for Phenobarbital. Read the label on DailyMed ›

  • Seizures Worth acting on Additional detail

    Delta-8-tetrahydrocannabinol (delta-8-thc)

    “Delta-8-THC has been reported to cause psychoactive effects and a feeling of being "high". It is estimated to be 50% to 75% as psychoactive as delta-9-THC, the primary psychoactive constituent of cannabis. Effects include euphoria, vision and time distortion, difficulty thinking and speaking, and a dream-like feeling.”

    Delta-8-tetrahydrocannabinol (delta-8-thc) · Natural Medicines adverse-effect record, reported in epilepsy.

    6 sources cited
    1. 106100. Johnson-Arbor K, Smolinske S. The current state of delta-8 THC. Am J Emerg Med 2021. PubMed
    2. 106107. US Food and Drug Administration (FDA). 5 things to know about delta-8 tetrahydrocannabinol - delta-8 THC. September 2021. https://www.fda.gov/consumers/consumer-updates/5-things-know-about-delta-8-tetrahydrocannabinol-delta-8-thc. Accessed October 2, 2021
    3. 106108. Centers for Disease Control and Prevention (CDC). Increases in availability of cannabis products containing delta-8 THC and reported cases of adverse events. September 2021. https://emergency.cdc.gov/han/2021/han00451.asp. Accessed October 2, 2021.
    4. 113017. Leas EC, Harati RM, Satybaldiyeva N, et al. Self-reported adverse events associated with ?(8)-Tetrahydrocannabinol (Delta-8-THC) Use. J Cannabis Res 2023;5(1):15. PubMed
    5. 113026. Simon TA, Simon JH, Heaning EG, Gomez-Caminero A, Marcu JP. Delta-8, a Cannabis-Derived Tetrahydrocannabinol Isomer: Evaluating Case Report Data in the Food and Drug Administration Adverse Event Reporting System (FAERS) Database. Drug Healthc Patient Saf PubMed
    6. 107322. Akpunonu P, Baum RA, Reckers A, et al. Sedation and Acute Encephalopathy in a Pediatric Patient Following Ingestion of Delta-8-Tetrahydrocannabinol Gummies. Am J Case Rep 2021;22:e933488. PubMed

    Phenobarbital

    Listed in the ADVERSE REACTIONS section of the FDA label for Phenobarbital. Read the label on DailyMed ›

  • Low blood pressure Additional detail

    Delta-8-tetrahydrocannabinol (delta-8-thc)

    Recorded for Delta-8-tetrahydrocannabinol (delta-8-thc) in the same Natural Medicines adverse-effect record shown under A slow heartbeat above.

    Phenobarbital

    Listed in the ADVERSE REACTIONS section of the FDA label for Phenobarbital. Read the label on DailyMed ›

  • Drowsiness Additional detail

    Delta-8-tetrahydrocannabinol (delta-8-thc)

    “A large case series reports pulmonary disorders (e.g., cough, dry throat, dyspnea, painful respiration) as some of the most frequently noted adverse effects with delta-8-THC after assessing a public forum of 98,700 subscribers. Of 183 adverse events related to delta-8-THC reported to the US Food and Drug Administration, 33 report dyspnea, 17 report respiratory disorder, and 15 report cough.”

    Delta-8-tetrahydrocannabinol (delta-8-thc) · Natural Medicines adverse-effect record, reported in cough.

    3 sources cited
    1. 113017. Leas EC, Harati RM, Satybaldiyeva N, et al. Self-reported adverse events associated with ?(8)-Tetrahydrocannabinol (Delta-8-THC) Use. J Cannabis Res 2023;5(1):15. PubMed
    2. 113026. Simon TA, Simon JH, Heaning EG, Gomez-Caminero A, Marcu JP. Delta-8, a Cannabis-Derived Tetrahydrocannabinol Isomer: Evaluating Case Report Data in the Food and Drug Administration Adverse Event Reporting System (FAERS) Database. Drug Healthc Patient Saf PubMed
    3. 113033. Bradley EK, Hoots BE, Bradley ES, Roehler DR. Unintentional ingestion of putative delta-8 tetrahydrocannabinol by two youth requiring critical care: a case report. J Cannabis Res 2023;5(1):9. PubMed

    Phenobarbital

    Listed in the ADVERSE REACTIONS section of the FDA label for Phenobarbital. Read the label on DailyMed ›

Reported for Delta-8-tetrahydrocannabinol (delta-8-thc) but not commonly for Phenobarbital: shortness of breath, hallucinations, a fast or pounding heartbeat and chest pain.

Effects for Phenobarbital come from the ADVERSE REACTIONS section of its FDA label; effects for Delta-8-tetrahydrocannabinol (delta-8-thc) come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Phenobarbital Is Prescribed For, and What Delta-8-tetrahydrocannabinol (delta-8-thc) Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Phenobarbital is a prescription medicine with approved uses on its FDA label. Delta-8-tetrahydrocannabinol (delta-8-thc) is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Phenobarbital is prescribed for: Phenobarbital tablets and oral solutions are used to treat generalized and partial seizures and as a sedative. Phenobarbital Sodium injection is used as a long-term anticonvulsant for generalized tonic-clonic and focal seizures, for emergency control of acute convulsive episodes (including status epilepticus), for sedation, short-term treatment of insomnia, and as a preanesthetic. It is also used in pediatric patients as an anticonvulsant and sedative, including before and after surgery. Sezaby (phenobarbital injection, intravenous) is specifically indicated for the treatment of neonatal seizures in term and preterm infants.

Read the rest of what Phenobarbital is prescribed for

It is not approved for use in adolescents or adults.

Delta-8-tetrahydrocannabinol (delta-8-thc) has been studied for:

  • Insomnia studied, not established Delta-8-tetrahydrocannabinol (delta-8-thc) has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Delta-8-tetrahydrocannabinol (delta-8-thc) for insomnia

    Although there is interest in using oral delta-8-THC for insomnia, there is insufficient reliable information about the clinical effects of delta-8-THC for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Phenobarbital on your own; if you are taking Delta-8-tetrahydrocannabinol (delta-8-thc) for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Delta-8-tetrahydrocannabinol (delta-8-thc) or Phenobarbital

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-8-tetrahydrocannabinol (delta-8-thc) or Phenobarbital, 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 Phenobarbital

This page covers Delta-8-tetrahydrocannabinol (delta-8-thc) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenobarbital page lists 174 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 Henbane (major).

By severity: 10 major · 143 moderate · 21 minor.

Open the Phenobarbital interaction page

How much people look this up

Where Delta-8-tetrahydrocannabinol (delta-8-thc) and 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-8-tetrahydrocannabinol (delta-8-thc)
Steady interest

#1,431 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Phenobarbital
Top half

#881 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Delta-8-tetrahydrocannabinol (delta-8-thc) reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Delta-8-tetrahydrocannabinol (delta-8-thc)

What is Delta-8-tetrahydrocannabinol (delta-8-thc)?

  • Relaxation and mild euphoria
  • Anxiety and stress
  • Sleep problems
  • Pain relief
  • Nausea
  • Appetite stimulation

Delta-8-THC is a mind-altering cannabis compound, usually made by chemically converting CBD from hemp, that produces effects similar to but often milder than regular (delta-9) THC. There is very little quality human research on its benefits, and the FDA has warned about safety concerns, unregulated products, and reports of harm. Its legal status varies, and it is not recommended during pregnancy, breastfeeding, or for people who must avoid intoxication.

Cannabinoid derived from hemp (Cannabis sativa) · Gummies, vape cartridges, tinctures, edibles, capsules, flower sprayed with extract

An interaction check asks whether these two react with each other — it does not ask whether Delta-8-tetrahydrocannabinol (delta-8-thc) is a good idea for someone in your situation. Here is what our Delta-8-tetrahydrocannabinol (delta-8-thc) record says about it on its own.

Delta-8-tetrahydrocannabinol (delta-8-thc): dosing

There is no established or standardized safe dose for delta-8-THC. Products vary widely in strength, and because the market is poorly regulated, the amount listed on the label may not match what is actually in the product.If a product is used, the general harm-reduction advice is to "start low and go slow," follow the product label, and wait long enough to feel the effects—edibles in particular can take a couple of hours to kick in, leading some people to take too much.

From our Delta-8-tetrahydrocannabinol (delta-8-thc) monograph — the full record covers uses, side effects and every documented interaction.

Read the full Delta-8-tetrahydrocannabinol (delta-8-thc) monograph & all interactions
Medication

About Phenobarbital

What Is Phenobarbital Used For?

Brand names: Phenobarbital, Solfoton, Luminal

Phenobarbital tablets and oral solutions are used to treat generalized and partial seizures and as a sedative. Phenobarbital Sodium injection is used as a long-term anticonvulsant for generalized tonic-clonic and focal seizures, for emergency control of acute convulsive episodes (including status epilepticus), for sedation, short-term treatment of insomnia, and as a preanesthetic. It is also used in pediatric patients as an anticonvulsant and sedative, including before and after surgery.

Sezaby (phenobarbital injection, intravenous) is specifically indicated for the treatment of neonatal seizures in term and preterm infants. It is not approved for use in adolescents or adults.

Most-Reported Side Effects for Phenobarbital

From FAERS, the FDA’s public side-effect reporting system (15,690 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Seizure 1,669 reports
Toxicity to various agents 647 reports
Status epilepticus 532 reports
Somnolence 492 reports
Multiple-drug resistance 475 reports
See full Phenobarbital drug information
Keep checking

Other Drugs & Delta-8-tetrahydrocannabinol (delta-8-thc)

Browse every other medication we’ve checked against Delta-8-tetrahydrocannabinol (delta-8-thc) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

We also checked Delta-8-tetrahydrocannabinol (delta-8-thc) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Delta-8-tetrahydrocannabinol (delta-8-thc) list.

See the full Delta-8-tetrahydrocannabinol (delta-8-thc) interactions page
See every supplement checked against Phenobarbital, ranked by severity
Evidence & sources

Delta-8-tetrahydrocannabinol (delta-8-thc) References

The 11 references that drive our Delta-8-tetrahydrocannabinol (delta-8-thc) monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Johnson-Arbor K, Smolinske S. The current state of delta-8 THC. Am J Emerg Med 2021. PubMed
  2. Rosenthal J, Howell M, Earl V, Malik M. Cannabinoid hyperemesis syndrome secondary to delta-8 THC use. Am J Med 2021. PubMed
  3. US Food and Drug Administration (FDA). 5 things to know about delta-8 tetrahydrocannabinol - delta-8 THC. September 2021. https://www.fda.gov/consumers/consumer-updates/5-things-know-about-delta-8-tetrahydrocannabinol-delta-8-thc. Accessed October 2, 2021
  4. Centers for Disease Control and Prevention (CDC). Increases in availability of cannabis products containing delta-8 THC and reported cases of adverse events. September 2021. https://emergency.cdc.gov/han/2021/han00451.asp. Accessed October 2, 2021.
  5. Akpunonu P, Baum RA, Reckers A, et al. Sedation and Acute Encephalopathy in a Pediatric Patient Following Ingestion of Delta-8-Tetrahydrocannabinol Gummies. Am J Case Rep 2021;22:e933488. PubMed
  6. Jo NY, Chu CC, Ramsey BC. Brugada Electrocardiogram Pattern Induced by Recreational Delta-8-Tetrahydrocannabinol (THC): A Case Report. Cureus 2021;13(10):e19058. PubMed
  7. Leas EC, Harati RM, Satybaldiyeva N, et al. Self-reported adverse events associated with ?(8)-Tetrahydrocannabinol (Delta-8-THC) Use. J Cannabis Res 2023;5(1):15. PubMed
  8. Simon TA, Simon JH, Heaning EG, Gomez-Caminero A, Marcu JP. Delta-8, a Cannabis-Derived Tetrahydrocannabinol Isomer: Evaluating Case Report Data in the Food and Drug Administration Adverse Event Reporting System (FAERS) Database. Drug Healthc Patient Saf PubMed
  9. Bradley EK, Hoots BE, Bradley ES, Roehler DR. Unintentional ingestion of putative delta-8 tetrahydrocannabinol by two youth requiring critical care: a case report. J Cannabis Res 2023;5(1):9. PubMed
  10. Shaker K, Nillas A, Ellison R, et al. Delta-8-Tetrahydrocannabinol Exposure and Confirmation in Four Pediatric Patients. J Med Toxicol 2023;19(2):190-195. PubMed
  11. Miller CR, Burk BG, Fargason RE, Birur B. Delta-8-THC association with psychosis: A case report with literature review. Front Psychiatry 2023;14:1103123. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital Together: Common Questions

Is it safe to take Delta-8-tetrahydrocannabinol (delta-8-thc) with Phenobarbital?
We do not list a known interaction between Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital have any of the same side effects?
Yes — our sources link each of them separately to 4 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Delta-8-tetrahydrocannabinol (delta-8-thc) and Phenobarbital used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Delta-8-tetrahydrocannabinol (delta-8-thc) in each. That is a conversation for your prescriber, especially if Phenobarbital is being adjusted to a target.
Does Phenobarbital interact with any supplements?
Yes. Phenobarbital has documented interactions with 174 supplements in our database — Delta-8-tetrahydrocannabinol (delta-8-thc) is not one of them. The Phenobarbital interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Delta-8-tetrahydrocannabinol (delta-8-thc) monograph Uses, safety profile, and every drug interaction in one place Phenobarbital drug information The full plain-English guide to this medication Phenobarbital supplement interactions Every supplement checked against 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 References The 11 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenobarbital and Delta-8-tetrahydrocannabinol (delta-8-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.