Aim To describe self-reported use of medications with pharmacogenetic guidance in the Our Future Health (OFH) cohort. Methods We focused on four key pharmacogenes - CYP2C19, CYP2C9, CYP2D6, and SLCO1B1 - and associated medications supported by high levels of evidence for clinical actionability according to the Clinical Pharmacogenetics Implementation Consortium (CPIC). We summarized self-reported pharmacogenetic medication use, assessed concurrent use, and stratified the findings by age, sex, and ethnicity. Results Self-reported medication use was analysed in 1.78 million OFH cohort participants included in the June 2025 data release. The cohort was 57.3% female, ranged in age from 18 to 95 years (mean 53.1 years), and 90.2% self-identified as being of White ethnicity. Participants reported use of 18 medication groups that were explicitly mentioned in the baseline questionnaire. Due to the structure of the baseline questionnaire, it was only possible to identify exposure to medication groups rather than mention of specific individual medications. Medications and medication groups with pharmacogenetic guidance included anti-depressants (selective serotonin reuptake inhibitors and tricyclics), statins, proton pump inhibitors, ibuprofen, opioids, clopidogrel and warfarin. A total of 25.2% (N=449,641) of the cohort reported using at least one of these medication groups, and were older, more likely to be female, and reported having more medical conditions than non-users. Concurrent use of these medications/medication groups metabolised by more than one of the four genes was common (37%). Conclusions Exposure to medications with pharmacogenetic guidance was prevalent, occurred in all age groups, and increased with age. The Our Future Health cohort will become an increasingly valuable resource for studying pharmacogenetics with further recruitment and the planned linkage to patient-level primary care prescribing data.

VS, WGN and JHM are co-founders of an early-stage health technology start-up, Fava Health Ltd.

VS, WGN and JHM are supported by Innovate UK (10058536) and the NHS England Genomics Programme through the Pharmacogenetics and Medicines Optimisation Network of Excellence. JHM is supported by the National Institute for Health and Care Research (NIHR) as an Academic Clinical Lecturer. WGN and JHM are supported by the Manchester NIHR Biomedical Research Centre BRC (NIHR 203956).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethical approval for Our Future Health was granted by the Cambridge East Research Ethics Committee. (REC reference: 21/EE/0016; date of opinion: 29 March 2021). The present study was approved on application to Our Future Health as project OFHS240243.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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Access to the June 2025 data release was facilitated by the Our Future Health Early Adopters Research Scholar programme in which authors Dixon and Wright Drakesmith participated. The data were analysed in the Our Future Health DNAnexus Trusted Research Environment (https://ourfuturehealth.dnanexus.com/). Access to the data used in our analysis will be facilitated to qualifying researchers on application to Our Future Health.