Codeine

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.

Active substance: Codeine

Examples of brand names: Codeinum phosphoricum Berlin-Chemie [DE]

ATC code: R05DA04

Main use (for orientation): Dry cough; analgesia in combinations

Documented research summary

THC and codeine were investigated together in mice. Enhanced inhibition of pain responses is not evidence of benefit, dose sparing or safety in humans.

Uncertainties and limitations

No assurance of safety from missing human interactions. Genotype, co-medication, THC/CBD content and routes can alter net effects; rare cannabinoids insufficiently investigated.

Research is limited to the specified date and protocol; it is not globally exhaustive. Brand names and authorisations do not constitute a complete current market overview.

Structured assessment

Category: Direct pair finding

Cannabinoid scope: 28 register names in the documented search family; neither 28 individual clinical trials nor a blanket assessment of all cannabinoids.

Evidence status: Pair-specific evidence, distinguished in the individual findings

Mechanism / drug context: Antinociception in an animal model; human codeine activation is a separate question.

Type of supporting material: See the separate original findings

Clinical interpretation: Requires individual assessment by a doctor or pharmacist. Lack of evidence does not establish safety; no dosage or discontinuation advice is provided.

Context: Codeine sulphate, oral single-ingredient tablets assessed rather than codeine/paracetamol. Codeine has weak opioid activity; CYP2D6 bioactivation to morphine is relevant to substantial analgesia.

Drug context and gaps in search results are not measured interactions. The source role below describes which statement the source actually supports.

Source role [CA_L_D0148]: Drug context

Statement supported: Supports dosage form, metabolism and/or known risks; alone, it does not substantiate a cannabinoid–drug pair finding.

Source: CODEINE SULFATE TABLET [LANNETT COMPANY, INC.] [CA_L_D0148]

Source role [CA_P_16687136]: Pair finding

Statement supported: THC enhanced or prolonged codeine antinociception in mice.

Source: Time course of the enhancement and restoration of the analgesic efficacy of codeine and morphine by delta9-tetrahydrocannabinol. [CA_P_16687136]

Scope of review: Individual research with documented title/abstract screening and targeted review of original sections. This is not exhaustive evidence that interactions are absent.

Unresolved source question: The complete stored individual review, label review, literature screening, conclusion and uncertainties were read. Targeted sections of original information were rechecked; no claim is made that all product information or full texts were completely revalidated.

Unresolved source question: The additionally listed Cichewicz et al. 1999 paper (PMID 10215664) was rechecked at abstract level; its original full text remains unresolved. The separately presented codeine–THC finding is based on Williams et al. 2006 and must not be read as a full-text finding from the 1999 paper.

Separately recorded findings

1 separately recorded finding. Each statement applies to its documented study context.

Δ9-THC – laboratory and animal studies

Finding ID: V6_D0148_1

Type of result: Finding within the documented study context

Observation: THC enhanced or prolonged codeine antinociception in mice.

Mechanism: Pharmacodynamic antinociception

Study type: Animal experiment

Context studied: Williams et al. 2006; oral animal exposure.

Clinical interpretation: No opioid-combination/dose-reduction recommendation.

Limitations and uncertainties: No human benefit/safety or codeine/CBD pharmacokinetic evidence.

Original sources for this finding: Time course of the enhancement and restoration of the analgesic efficacy of codeine and morphine by delta9-tetrahydrocannabinol. [CA_P_16687136]

References and access status

[CA_L_D0148] CODEINE SULFATE TABLET [LANNETT COMPANY, INC.]

Original source / bibliographic reference

Authors: Lannett Company, Inc.

Year: 2026

Source type: Current published human-use SPL / product information

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

Bibliographic attribution or source identity cross-checked.

[CA_P_16687136] Time course of the enhancement and restoration of the analgesic efficacy of codeine and morphine by delta9-tetrahydrocannabinol.

Original source / bibliographic reference

Authors: Williams IJ, Edwards S, Rubo A, Haller VL, Stevens DL, Welch SP.

Year: 2006

Source type: Journal Article; Research Support, N.I.H., Extramural

DOI: 10.1016/j.ejphar.2006.04.003

PMID: 16687136

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

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

[CA_P_12604676] Antinociceptive synergy between delta(9)-tetrahydrocannabinol and opioids after oral administration.

Original source / bibliographic reference

Authors: Cichewicz DL, McCarthy EA.

Year: 2003

Source type: Research Support, U.S. Gov't, P.H.S.; Journal Article

DOI: 10.1124/jpet.102.045575

PMID: 12604676

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)

[CA_P_10215664] Enhancement mu opioid antinociception by oral delta9-tetrahydrocannabinol: dose-response analysis and receptor identification.

Original source / bibliographic reference

Authors: Cichewicz DL, Martin ZL, Smith FL, Welch SP.

Year: 1999

Source type: Preclinical animal experiment; bibliographic record and abstract assessed; original full text not yet fully assessed

PMID: 10215664

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

Bibliographic attribution or source identity cross-checked.

Unresolved access questions / further review: Bibliographic details and abstract reassessed on 23 October 2026. The paper investigates pain responses in an animal model after oral THC–opioid combination; it establishes neither clinical benefit, dose sparing nor safety in humans. The original full text could not be retrieved completely through the publisher routes assessed. Full-text assessment of methods, tables and safety endpoints remains open. The DOI and additional bibliographic record concern the same 1999 paper, not additional studies.

DOI – publisher access (full-text access not confirmed) – The registered DOI is unambiguously matched by title, authors, year and pages. The publisher full text was not successfully retrieved.

Europe PMC – bibliographic data and abstract (JSON; not full text) – Official bibliographic record successfully checked. The view is machine-readable and is not the original full text.

[CA_P_37652187] Modulatory effects of Cannabis sativa co-administration with tramadol and codeine on cognitive function in male rats.

Original source / bibliographic reference

Authors: Ademosun AO, Ajeigbe OF, Lawrence BO, Oboh G.

Year: 2023

Source type: Journal Article

DOI: 10.1016/j.neuro.2023.08.005

PMID: 37652187

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)

[CA_P_31496363] Reduced urinary opioid levels from pain management patients associated with marijuana use.

Original source / bibliographic reference

Authors: Goggin MM, Shahriar BJ, Stead A, Janis GC.

Year: 2019

Source type: Journal Article

DOI: 10.2217/pmt-2019-0017

PMID: 31496363

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.

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