Where is pharmacogenomic testing already proven and ready for use?
The strongest evidence supports testing for specific gene variants before using certain high-risk drugs. The most clear-cut example is DPYD genotyping before treatment with fluoropyrimidine chemotherapies (5-fluorouracil and capecitabine). About 3–8% of people of European descent carry DPYD variants that dramatically increase their risk of severe, life-threatening toxicity, including death in up to 1% of cases [1]. Pre-emptive testing and dose adjustment reduces this risk without compromising cancer treatment, and this approach is now standard of care in the Netherlands, France, Germany, and the UK [1]. A large, prospective European trial (the PREPARE study) provided the first randomized evidence that using a broader panel of pharmacogenomic tests before prescribing across seven healthcare systems reduced the risk of clinically relevant toxicities by 30% [4]. This shows that for a set of well-validated drug-gene pairs, the testing is both feasible and beneficial in real-world clinical settings.
In Australia, Medicare rebates currently cover only two specific tests: TPMT (for the drugs azathioprine, mercaptopurine, and thioguanine) and HLA-B*57:01 (for the HIV drug abacavir) [11]. These are examples where the evidence is strong enough that public health systems have deemed testing cost-effective. The American College of Medical Genetics and Genomics (ACMG) has also published technical standards to guide laboratories in offering reliable clinical pharmacogenomic testing, underscoring that the science is mature enough for clinical use when applied to genes and variants with sufficiently high levels of evidence [9].
What is still holding it back from routine clinical practice?
Despite the proven benefits for specific drug-gene pairs, several major barriers prevent pharmacogenomic testing from being adopted as a routine part of care. The most commonly cited obstacle is cost and lack of insurance coverage. In a large survey of over 1,000 clinical pharmacists in China, 76.7% identified high cost or lack of insurance as the top challenge [3]. This is echoed in Australia, where most pharmacogenomic tests are paid for out-of-pocket by patients, as only two tests attract a Medicare rebate [1][11]. Without clear reimbursement pathways, healthcare systems and patients are reluctant to pay for testing, even when it is clinically useful.
A second critical barrier is the lack of knowledge and training among healthcare professionals. Multiple surveys show that community pharmacists and clinical pharmacists consistently rate their own understanding of pharmacogenomics as poor or average [2][3][8]. For example, a study of community pharmacists in the UAE found that most had poor knowledge (median score <8 out of a possible high score), and nearly half did not have a positive attitude toward testing [2]. Similarly, a study in England found that 63% of community pharmacists had limited familiarity with pharmacogenomics, and only 2 out of 51 had received any relevant training [8]. This knowledge gap means that even when test results are available, clinicians may not know how to interpret or act on them, limiting the real-world impact.
A third major hurdle is the inconsistency in clinical practice guidelines and regulatory recommendations. Most medical professional societies do not recommend routine pharmacogenomic testing, with only a few key exceptions [6]. This creates confusion for clinicians about who to test and when. The FDA product labeling for some drugs includes pharmacogenomic information, but it does not always align with guidelines from groups like the Clinical Pharmacogenetics Implementation Consortium (CPIC) [6]. This patchwork of recommendations makes it difficult for healthcare systems to develop standardized, evidence-based protocols.
Who should consider pharmacogenomic testing today?
Given the current evidence and limitations, the most appropriate candidates for pharmacogenomic testing are patients who are about to start a medication with a well-established gene-drug interaction. This is often called 'pretreatment' or 'reactive' testing, as opposed to testing everyone pre-emptively [6]. The strongest candidates include patients about to receive fluoropyrimidine chemotherapy (for DPYD testing), patients starting the blood thinner clopidogrel (for CYP2C19 testing), and patients being considered for the HIV drug abacavir (for HLA-B*57:01 testing) [1][11]. In these cases, the test result directly informs a critical prescribing decision—either adjusting the dose or choosing an alternative drug—and the evidence for benefit is strong.
Pre-emptive testing—screening a person for many gene variants before any specific drug is prescribed—is a more ambitious goal. While the PREPARE study showed it can reduce overall adverse drug reactions by 30% [4], it is not yet widely implemented due to the cost and infrastructure challenges discussed above. Some academic medical centers, like UCSF Health and a large US academic center, have successfully built systems to pre-emptively test patients and link results to electronic health records with clinical decision support alerts [5][7]. However, these remain pioneering efforts, not yet the standard of care. For the average patient today, the most practical approach is to discuss with their doctor whether testing is recommended for a specific medication they are about to take.
About These Sources
This answer is built on 11 peer-reviewed studies — published from 2022 to 2025, 6 from 2024 or later, 4 in Q1 journals, collectively cited 121 times — selected as the most relevant from 15 studies that passed quality screening, drawn from 67 papers retrieved from a database of over 500 million.
Sources used in this answer
Pharmacogenomics in the era of personalised medicine
Argues Australia should implement a national DPYD genotyping program for fluoropyrimidine chemotherapy, citing that 3-8% of Europeans carry DPYD variants that greatly increase toxicity risk, and that upfront testing is cost-effective and standard in several European countries.
Investigation of community pharmacists’ knowledge and attitudes of pharmacogenomics testing: implication for improved pharmacogenomic testing practice
A cross-sectional survey of community pharmacists in the UAE found poor knowledge (median score <8) and that 43.9% lacked a positive attitude toward pharmacogenomic testing, with higher patient volumes associated with worse knowledge.
Clinical Pharmacists’ Knowledge of and Attitudes toward Pharmacogenomic Testing in China
A survey of 1,005 clinical pharmacists in China found 99% had heard of pharmacogenomic testing, but only 25% rated their knowledge as good or excellent; 77% believed it could improve efficacy and reduce adverse reactions, and 76.7% cited high cost or lack of insurance as the top barrier.
Implementation of pre‐emptive testing of a pharmacogenomic panel in clinical practice: Where do we stand?
Reviews the evolution from single-gene reactive testing to pre-emptive panels, highlighting the PREPARE study (a large prospective randomized trial in Europe) which showed a 30% reduction in clinically relevant toxicities with pre-emptive panel testing, but notes unanswered questions about cost-effectiveness and transferability to non-European populations.
Implementation of Integrated Clinical Pharmacogenomics Testing at an Academic Medical Center.
Describes successful implementation of an 11-gene pharmacogenomics panel at a US academic medical center, with a mean turnaround time of 4.6 days, 22.1% of orders having an actionable result, and 67% of orders associated with an electronic consultation.
Navigating Pharmacogenomic Testing in Practice: Who to Test and When to Test
Discusses the lack of consistent recommendations across clinical practice guidelines, FDA labeling, and payer policies for pharmacogenomic testing, and provides perspectives on who to test and when, comparing preemptive, pretreatment, and reactive testing models.
Clinical implementation of preemptive pharmacogenomics testing for personalized medicine at an academic medical center
Describes the implementation of a preemptive pharmacogenomics program at UCSF Health, including a customized panel for 56 medications and 15 genes, with 233 prescribing alerts and 15 testing prompts integrated into the electronic health record.
Are Community Pharmacists Ready to Deliver Pharmacogenomics Testing Services?
A survey of 51 community pharmacists in England found 63% had limited familiarity with pharmacogenomics, only 2 had received relevant training, and time constraints and lack of knowledge were key barriers, though over 60% were willing to provide testing after training.
Clinical pharmacogenomic testing and reporting: A technical standard of the American College of Medical Genetics and Genomics (ACMG)
Provides a technical standard from the ACMG for clinical pharmacogenomic testing, detailing best practices for nomenclature, testing, result interpretation, and reporting, emphasizing that genes and variants with sufficiently high evidence may be included.
Pharmacogenomics and Personalized Medicine: A Revolution in Drug Therapy
Reviews the scientific foundations and clinical applications of pharmacogenomics, noting advanced use in oncology, cardiology, psychiatry, and infectious diseases, but identifies barriers including limited clinician awareness, high costs, and insufficient regulatory frameworks.
Using pharmacogenomics to personalise drug therapy: which drugs, when and how
States that pharmacogenomic testing is recommended for several drugs (e.g., allopurinol, clopidogrel) but only TPMT and HLA-B*57:01 testing are currently Medicare-rebated in Australia, and emphasizes that results must be interpreted in clinical context.