Drug & supplement interaction

Cannabidiol (cbd) + Flutamide

Flutamide brand names: Eulexin, Euflex.

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

Flutamide falls into 2 drug categories that Cannabidiol (cbd) can interact with; the most serious is rated moderate. Cannabidiol may increase levels of drugs metabolized by CYP1A2.

Read the full interaction report
SeverityModerate
LikelihoodProbable
Interactions2
EvidenceA
What do Severity, Likelihood & Evidence mean?
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Interaction report

Cannabidiol (cbd) and Flutamide

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

Why Are There 2 Interactions?

Cannabidiol (cbd) interacts with whole categories of medication. Flutamide falls into 2 of those categories, so it can interact with Cannabidiol (cbd) in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

1 of 2

Why this applies to Flutamide

Flutamide falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Cannabidiol (cbd) interacts with.

Cannabidiol may increase levels of drugs metabolized by CYP1A2.
In vitro research shows that cannabidiol inhibits CYP1A2. Furthermore, clinical studies show that cannabidiol may inhibit the metabolism of caffeine, a CYP1A2 substrate. Two pharmacokinetic studies in healthy adults show that taking cannabidiol dosed 640 mg once up to 750 twice daily increases the area under the curve of caffeine. However, results are mixed over whether cannabidiol impacts peak serum levels of caffeine.
Severity Moderate Likelihood Probable Evidence A

Interaction 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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know if you're on flutamide for prostate cancer and thinking about CBD. Your liver uses an enzyme called CYP1A2 to help process flutamide, and CBD can slow that enzyme down. When the enzyme works slower, more of the drug can hang around in your body than expected.

For flutamide, higher levels could mean a bit more of its usual side effects, things like diarrhea, hot flashes, breast tenderness, or strain on the liver. Flutamide already carries a liver warning, so that's the piece I'd watch most closely. Keep in mind these studies used large CBD doses, so smaller amounts may matter less. Please don't stop or change anything on your own. Just loop in your pharmacist or oncologist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yamaori S, Kushihara M, Yamamoto I, Watanabe K. Characterization of major phytocannabinoids, cannabidiol and cannabinol, as isoform-selective potent inhibitors of human CYP1 enzymes. Biochem Pharmacol 2010;79(11):1691-8.
  2. Thai C, Tayo B, Critchley D. A Phase 1 Open-Label, Fixed-Sequence Pharmacokinetic Drug Interaction Trial to Investigate the Effect of Cannabidiol on the CYP1A2 Probe Caffeine in Healthy Subjects. Clin Pharmacol Drug Dev. 2021. PubMed
  3. 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
  4. Bansal S, Zamarripa CA, Spindle TR, et al. Evaluation of Cytochrome P450-Mediated Cannabinoid-Drug Interactions in Healthy Adult Participants. Clin Pharmacol Ther 2023.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

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

Cannabidiol may increase levels of drugs that are metabolized by CYP3A4.
In vitro and animal research shows that cannabidiol inhibits CYP3A4. In human studies and case reports, cannabidiol has been associated with an increase in plasma levels of the CYP3A4 substrates zonisamide, tacrolimus, everolimus, citalopram, midazolam, and methadone.
Severity Moderate Likelihood Probable Evidence A

Interaction 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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for your prostate cancer treatment. Your liver uses an enzyme called CYP3A4 to help process flutamide. CBD can slow that enzyme down, which means flutamide may not clear as quickly and could build up a bit higher in your body than usual.

In practical terms, that could mean more of flutamide's typical side effects, like nausea, diarrhea, hot flashes, or fatigue. The bigger concern with this medicine is its effect on the liver, so anything that raises its levels deserves attention. The lab and human evidence on CBD blocking this enzyme is fairly strong, but it hasn't been studied with flutamide specifically. Please don't stop either one on your own. Just loop in your oncologist or pharmacist first so they can watch your liver labs and adjust if needed.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yamaori S, Ebisawa J, Okushima Y, et al. Potent inhibition of human cytochrome P450 3A isoforms by cannabidiol: role of phenolic hydroxyl groups in the resorcinol moiety. Life Sci 2011;88(15-16):730-6. PubMed
  2. Harvey DJ. Absorption, distribution, and biotransformation of the cannabinoids. Marijuana and Medicine. 1999;91-103. DOI
  3. Bornheim LM, Everhart ET, Li J, Correia MA. Characterization of cannabidiol-mediated cytochrome P450 inactivation. Biochem Pharmacol 1993;45(6):1323-31. PubMed
  4. 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
  5. Leino AD, Emoto C, Fukuda T, Privitera M, Vinks AA, Alloway RR. Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus. Am J Transplant. 2019;19(10):2944-2948. PubMed
  6. Wiemer-Kruel A, Stiller B, Bast T. Cannabidiol Interacts Significantly with Everolimus-Report of a Patient with Tuberous Sclerosis Complex. Neuropediatrics. 2019. PubMed
  7. Madden K, Tanco K, Bruera E. Clinically Significant Drug-Drug Interaction Between Methadone and Cannabidiol. Pediatrics. 2020;e20193256. PubMed
  8. 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
  9. 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
  10. 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
  11. 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

Cannabidiol (cbd) Also Interacts With Other Medications

Cannabidiol (cbd) has 1,050 moderate known drug interactions in our database — the Flutamide one above is among them. If you take anything else, check it against the full list below.

Moderate 1,050 No known interaction 1,780 (incl. Flutamide)
Taking anything else?

Check Another of Your Medications Against Cannabidiol (cbd)

Covers the 2,830 medications we’ve checked against Cannabidiol (cbd). Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Flutamide

This page covers Cannabidiol (cbd) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Flutamide page lists 189 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 143 moderate · 43 minor.

From our pharmacist’s overview on the Flutamide page

“A man taking flutamide (Eulexin) to block testosterone during prostate cancer treatment cannot afford big swings in the drug's level, and most of the 189 supplements on this page are capable of causing exactly that. The bulk of them work through the liver enzyme CYP3A4, which breaks flutamide down.”

Reviewed by 2 · Jul 18, 2026

Open the Flutamide interaction page

How much people look this up

Where Cannabidiol (cbd) and Flutamide 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 Cannabidiol (cbd)
Top half

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

29 days ago today
Medication Flutamide
Top half

#1,229 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 Cannabidiol (cbd)

What is Cannabidiol (cbd)?

  • Anxiety and stress
  • Sleep problems
  • Chronic pain
  • Certain seizure disorders
  • Inflammation

CBD is a compound from the cannabis (hemp) plant that does not cause a 'high.' It has strong evidence only for certain rare seizure disorders (as a prescription drug), while most other popular uses are still backed by limited or early research. Product quality varies a lot, so talk with your pharmacist or doctor before using it, especially if you take other medicines.

Read the full Cannabidiol (cbd) monograph & all interactions
Medication

About Flutamide

What Is Flutamide Used For?

Brand names: Eulexin, Euflex

Eulexin (flutamide) capsules are used to treat prostate cancer in men. They are always used together with an LHRH agonist (a hormone-lowering injection), never alone.

Eulexin is indicated for two stages of prostate cancer: locally confined Stage B2-C prostate cancer (used alongside goserelin acetate and radiation therapy, starting eight weeks before radiation begins) and Stage D2 metastatic prostate cancer (cancer that has spread beyond the prostate, taken with an LHRH agonist until the disease progresses).

See full Flutamide drug information
Keep checking

Other Drugs & Cannabidiol (cbd)

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

0Major
1,050Moderate
0Minor
1,779No known interaction
1,050 Moderate 1,779 No interaction
Moderate

1,050 interactions

Showing 60 of 1,050 moderate interactions — see all 1,050 on the Cannabidiol (cbd) page.

No interaction 1,779 drugs checked — show the list

We also checked Cannabidiol (cbd) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,779 medications checked with no known interaction — see the full Cannabidiol (cbd) list.

See the full Cannabidiol (cbd) interactions page
See every supplement checked against Flutamide, 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
Cannabidiol (cbd) monograph › Uses, safety, and every drug interaction in one place Flutamide supplement interactions › Every supplement checked against Flutamide, ranked by severity Flutamide 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 Cannabidiol (cbd) and Flutamide Together: Common Questions

Can you take Cannabidiol (cbd) with Flutamide?
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 Cannabidiol (cbd) and Flutamide?
Flutamide belongs to more than one drug category, and Cannabidiol (cbd) 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 Cannabidiol (cbd) and Flutamide 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 Flutamide and Cannabidiol (cbd)?

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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.