Classes, combinations and metabolites

For an informed discussion with your doctor or pharmacist. This information collection is not a clinically validated interaction checker. Missing data do not establish safety. Do not change or stop prescribed medicines on the basis of this information. The findings apply to the specific conditions studied; laboratory and animal studies cannot be directly extrapolated to humans.

Additional findings on classes, combinations and metabolites

These eight findings are not automatically attributed to individual drugs and are not counted in addition to the 454 drugs.

Hormonal contraceptives (class)

CBD + Δ9-THC (nabiximols) – theoretical plausibility

Finding ID: B0049

Type of result: Untested clinical possibility

Observation: Reduced efficacy possible.

Mechanism: In-vitro enzyme/transporter induction

Study type: Regulatory class warning

Context studied: No clinical failure evidence stated.

Clinical interpretation: Potentially high

Limitations and uncertainties: Do not code as proven failure of individual contraceptives.

Original sources for this finding: Sativex Oromucosal Spray – Summary of Product Characteristics [CL19]

Ethanol

CBD + Δ9-THC (nabiximols) – theoretical plausibility

Finding ID: B0050

Type of result: Untested clinical possibility

Observation: Coordination/reaction may be more impaired.

Mechanism: Additive CNS effect

Study type: Regulatory warning

Context studied: External alcohol consumption, not just an excipient in the spray.

Clinical interpretation: Possible

Limitations and uncertainties: No quantified pair study extracted.

Original sources for this finding: Sativex Oromucosal Spray – Summary of Product Characteristics [CL19]

Immune checkpoint inhibitors (mixed therapies; not an isolated individual drug)

Heterogeneous cannabis exposure; predominantly dronabinol (82%) – clinical signals

Finding ID: B0102

Type of result: Context-specific finding; read the limitations

Observation: Exposure was associated with worse overall survival (adjusted HR 2.25; 95% CI 1.25–4.05) and progression-free survival (adjusted HR 2.21; 1.33–3.68).

Mechanism: Possible immunological pharmacodynamic interaction; observational association, mechanism unproven

Study type: Retrospective single-centre observational study

Context studied: 106 records reviewed, 105 analysed: 28 exposed and 77 unexposed; treatment 2014–2018. Several checkpoint inhibitors analysed together.

Clinical interpretation: Individual oncological assessment; not a causal effect or a self-applied treatment-change factor

Limitations and uncertainties: Not randomised; age/tobacco-use differences, incompletely recorded exposure and possible residual confounding by symptoms/disease burden. No separate CBD, THC or individual-drug effect.

Original sources for this finding: Association between cannabis use and clinical outcomes in patients with solid malignancies receiving immune checkpoint inhibitors [EX15]

Irinotecan (active metabolite SN-38)

CBD – laboratory and animal studies

Finding ID: B0196

Type of result: Preclinical evidence

Observation: Cannabinoid 1 µM reduced the permeability increase induced by SN-38 (5 µM).

Mechanism: Epithelial barrier

Study type: Cell / animal experiment, abstract read

Context studied: Cell model of intestinal mucositis; not an irinotecan pharmacokinetic test.

Clinical interpretation: Not clinically validated

Limitations and uncertainties: No human drug–drug interaction; not a treatment recommendation.

Original sources for this finding: Selected phytocannabinoids inhibit SN-38- and cytokine-evoked increases in epithelial permeability and improve intestinal barrier function in vitro. [BMED38950639]

Irinotecan (active metabolite SN-38)

CBG – laboratory and animal studies

Finding ID: B0197

Type of result: Preclinical evidence

Observation: Cannabinoid 1 µM reduced the permeability increase induced by SN-38 (5 µM).

Mechanism: Epithelial barrier

Study type: Cell / animal experiment, abstract read

Context studied: Cell model of intestinal mucositis; not an irinotecan pharmacokinetic test.

Clinical interpretation: Not clinically validated

Limitations and uncertainties: No human drug–drug interaction; not a treatment recommendation.

Original sources for this finding: Selected phytocannabinoids inhibit SN-38- and cytokine-evoked increases in epithelial permeability and improve intestinal barrier function in vitro. [BMED38950639]

Irinotecan (active metabolite SN-38)

CBDV – laboratory and animal studies

Finding ID: B0198

Type of result: Preclinical evidence

Observation: Cannabinoid 1 µM reduced the permeability increase induced by SN-38 (5 µM).

Mechanism: Epithelial barrier

Study type: Cell / animal experiment, abstract read

Context studied: Cell model of intestinal mucositis; not an irinotecan pharmacokinetic test.

Clinical interpretation: Not clinically validated

Limitations and uncertainties: No human drug–drug interaction; not a treatment recommendation.

Original sources for this finding: Selected phytocannabinoids inhibit SN-38- and cytokine-evoked increases in epithelial permeability and improve intestinal barrier function in vitro. [BMED38950639]

Irinotecan (SN-38)

CBD – laboratory and animal studies

Finding ID: B0199

Type of result: Preclinical evidence

Observation: Strong CBD plus SN-38 synergy in MCF7 across several models.

Mechanism: Cytotoxic synergy

Study type: Cell / animal experiment, abstract read

Context studied: Directly tested SN-38, not a clinical irinotecan experiment.

Clinical interpretation: Not clinically validated

Limitations and uncertainties: No human drug–drug interaction; not a treatment recommendation.

Original sources for this finding: Synergistic Interactions of Cannabidiol with Chemotherapeutic Drugs in MCF7 Cells: Mode of Interaction and Proteomics Analysis of Mechanisms. [BMED34576262]

Durvalumab + tremelimumab (combination, sometimes with chemotherapy; not an isolated individual drug)

Heterogeneous cannabinoid exposure defined by each study – clinical signals

Finding ID: B0530

Type of result: Mixed/context-dependent finding

Observation: Exposure at baseline: no adjusted association with progression-free survival (p=0.12), overall survival (p=0.35) or immune-related adverse effects; borderline favourable immune-related progression-free survival signal (p=0.05).

Mechanism: Clinical observation; no measured pharmacokinetics or isolated immunological mechanism

Study type: Retrospective exposure analysis of pooled individual data from four CCTG trials

Context studied: 684 people; 32 exposed at baseline, 65 at any study time. BR.34, CO.26, PA.7 and IND.226.

Clinical interpretation: Contrasting/additional finding to general immune-checkpoint-inhibitor risk claims; not safety clearance

Limitations and uncertainties: Non-randomised, incompletely characterised exposure. Definition includes propacetamol, a paracetamol prodrug; possible misclassification influence cannot be quantified, supplement inaccessible. Wide safety confidence intervals; no general assurance of safety or direct nivolumab/pembrolizumab pair study.

Original sources for this finding: Effects of cannabinoids on immune checkpoint inhibitor response: CCTG pooled analysis of individual patient data [V4_CCTG_40184324]; Early bioavailability of paracetamol after oral or intravenous administration [V5C_PROPACETAMOL_15242431]

References and access status

[CL19] Sativex Oromucosal Spray – Summary of Product Characteristics

Original source / bibliographic reference

Authors: SVX Therapeutics Limited

Year: 2026

Source type: Regulatory product information

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

[EX15] Association between cannabis use and clinical outcomes in patients with solid malignancies receiving immune checkpoint inhibitors

Original source / bibliographic reference

Authors: Hadid T; Biedny A; Mamdani H; Azmi A; Kim S; Jang H; Uprety D; Al Hallak MN; Sukari A

Year: 2024

Source type: Retrospective single-centre observational study

DOI: 10.1177/25151355241309095

PMID: 39737331

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

DOI – publisher access (access restrictions may apply)

[BMED38950639] Selected phytocannabinoids inhibit SN-38- and cytokine-evoked increases in epithelial permeability and improve intestinal barrier function in vitro.

Original source / bibliographic reference

Authors: Marsh DT, Smid SD.

Year: 2024

Source type: Publication; title and abstract reviewed

DOI: 10.1016/j.tiv.2024.105888

PMID: 38950639

Source access – 23 October 2026: Automated direct retrieval was restricted; this does not establish that the link is broken.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

DOI – publisher access (access restrictions may apply)

[BMED34576262] Synergistic Interactions of Cannabidiol with Chemotherapeutic Drugs in MCF7 Cells: Mode of Interaction and Proteomics Analysis of Mechanisms.

Original source / bibliographic reference

Authors: Alsherbiny MA, Bhuyan DJ, Low MN, Chang D, Li CG.

Year: 2021

Source type: Publication; title and abstract reviewed

DOI: 10.3390/ijms221810103

PMID: 34576262

Source access – 23 October 2026: Automated direct retrieval was restricted; this does not establish that the link is broken.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

PubMed Central – archived text

DOI – publisher access (access restrictions may apply)

[V4_CCTG_40184324] Effects of cannabinoids on immune checkpoint inhibitor response: CCTG pooled analysis of individual patient data

Original source / bibliographic reference

Authors: Coschi CH; Ding K; Tong J; Tu D; O'Callaghan C; Leighl NB; Vera-Badillo F; Juergens RA; Hao D; Seymour L; Renouf DJ; Chen E; Gaudreau PO; Fung AS

Year: 2025

Source type: Retrospective exposure analysis of pooled individual data

DOI: 10.1080/1750743X.2025.2485012

PMID: 40184324

Source access – 23 October 2026: Automated direct retrieval was restricted; this does not establish that the link is broken.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

DOI – publisher access (access restrictions may apply)

Europe PMC – full-text access according to the literature database – Listed as freely available HTML full text in the official Europe PMC metadata. Direct retrieval was not fully verified here.

[V5C_PROPACETAMOL_15242431] Early bioavailability of paracetamol after oral or intravenous administration

Original source / bibliographic reference

Authors: Holmér Pettersson P; Owall A; Jakobsson J

Year: 2004

Source type: Original clinical study

DOI: 10.1111/j.0001-5172.2004.00452.x

PMID: 15242431

Source access – 23 October 2026: Direct retrieval could not be fully verified; availability remains unresolved.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

Research as of 23 October 2026. Not all original full texts could be reviewed in full. Source accessibility and the strength of scientific evidence must be assessed separately. An accessible link does not establish medical approval; a bibliographic record with an abstract does not replace the original full text.

Drug search and explanation of the evidence · Guide: cannabinoids and medicines · Author and responsibility