How Pharmacogenomic Testing Can Reduce Adverse Drug Reactions

Mental health medicines can restore stability, reduce distress and help people participate in daily life. They can also cause unwanted effects such as nausea, sedation, weight gain, movement disorders, sexual dysfunction, agitation or dangerous changes in blood chemistry. Pharmacogenomic testing examines inherited differences in drug metabolism and response, helping clinicians select or adjust medicines with greater knowledge of an individual’s likely risk.

This approach is relevant across Australia, where people may receive care through a general practitioner, public hospital, private psychiatrist, community mental health service or Aboriginal Community Controlled Health Organisation. Translating genetic evidence into practical prescribing decisions requires good clinical governance, informed consent, reliable laboratory testing and partnerships between researchers and health services.

Why Adverse Reactions Happen

People process medicines differently. Variants in genes such as CYP2D6 and CYP2C19 can alter how quickly the liver breaks down several antidepressants and antipsychotics. A person who metabolises a medicine slowly may develop high blood concentrations at a standard dose, while a rapid metaboliser may receive too little benefit. Age, kidney or liver disease, smoking, alcohol and other medicines can also change exposure.

Pharmacogenomic results may therefore support a more personalised starting dose or guide the choice of an alternative medicine. The testing does not predict every side effect, and it cannot replace a careful history. For example, sedation may be influenced by several genes, sleep patterns, other medicines and the person’s underlying condition.

The greatest value may occur when someone has experienced repeated treatment failures or adverse drug reactions. A genetic result can provide an explanation for unusual sensitivity and reduce the need for multiple trial-and-error changes, although the final decision remains a clinical one.

Medicines And Genes In Mental Health Care

Clinical pharmacogenomic panels commonly report genes linked to antidepressant metabolism, including CYP2C19 and CYP2D6. Some reports also include pharmacodynamic markers, although the strength of evidence varies. For selected medicines, testing can indicate whether a standard dose is likely to produce higher or lower exposure than expected.

Antipsychotic treatment requires particular care. Genetic information may help with medicines such as aripiprazole or risperidone, yet weight, diabetes risk, smoking and interactions remain important. A person taking several medicines may have changes in metabolism caused by drug interactions, even when their genetic result is known.

Some severe reactions have a stronger genetic association. HLA-B15:02 is linked with carbamazepine-related Stevens–Johnson syndrome and toxic epidermal necrolysis in people with particular Asian ancestry, while HLA-B57:01 is relevant to abacavir hypersensitivity. These examples show why ancestry, family history and the medicine being considered should guide targeted testing rather than broad genetic screening alone.

Making Testing Useful In Australia

Australian clinicians need to consider the quality and interpretation of commercial tests. Laboratories should use validated methods and provide clinically meaningful reports, rather than simply listing gene variants. NATA accreditation, professional standards and transparent evidence sources can help health services assess providers. The Therapeutic Goods Administration also has a role in the regulation of medical devices and certain diagnostic products.

Cost and access are practical issues. A pharmacogenomic panel may not be routinely covered by Medicare or the Pharmaceutical Benefits Scheme, so patients can face out-of-pocket charges. Availability can differ between Brisbane, Sydney, Melbourne, regional Queensland and remote communities. A test is less useful if the result is difficult to obtain, poorly explained or absent from the patient’s medical record.

Privacy matters because genetic information can affect a person and their biological relatives. Clinicians should explain what is being tested, how results will be stored, who may access them and whether data could be used for research. These decisions should align with Australian privacy requirements and the National Statement on Ethical Conduct in Human Research.

From Research To Clinical Practice

Pharmacogenomics works best as part of a broader medication safety pathway. Before prescribing, clinicians can review previous reactions, current medicines, supplements, smoking status, alcohol use and physical health. After a medicine begins, follow-up should assess response, side effects, adherence and any need for dose adjustment.

This principle resembles other efforts to translate evidence into safer care, including guidance on pain assessment in intensive care, where clinicians must combine structured tools with observation and professional judgement. In mental health, patients may have difficulty describing internal symptoms, particularly during severe depression, psychosis, cognitive impairment or acute distress.

Research partnerships can test whether pharmacogenomic services improve outcomes in real Australian settings. Translational projects might measure hospital admissions, treatment discontinuation, symptom improvement, emergency presentations and patient-reported quality of life. Current opportunities for this type of work are reflected in new translational funding, which can help connect laboratories, universities and health services.

Supporting Patients And Clinicians

A genetic report should be explained in plain language. Patients need to know whether the result recommends a different medicine, a lower starting dose, closer monitoring or no change. The report should avoid deterministic statements such as “this medicine will fail”; genetic evidence usually changes probabilities rather than providing certainty.

Shared decision-making is especially important in psychiatry. Someone who has previously experienced severe side effects may feel understandably cautious about trying another medicine. Discussing likely benefits, alternatives, monitoring plans and warning signs can improve trust. Written information and an updated medication list are useful when care moves between a GP in Toowoomba, a psychiatrist in Brisbane and an emergency department elsewhere.

Education should extend to pharmacists, nurses and other professionals involved in medicines management. Australian patients often obtain prescriptions from several services and may use digital health records, community pharmacies or telehealth appointments. A consistent process for recording pharmacogenomic results can prevent repeated testing and reduce the risk that an important finding is overlooked.

Balancing Benefits, Limits And Equity

The potential advantages are clearest when a well-supported gene–medicine association applies to the prescribed drug. The limitations are equally important: many tests include markers with uncertain evidence, results may not cover every relevant gene, and environmental factors can outweigh genetic effects. Testing should never delay urgent treatment or replace monitoring for suicidal thinking, mania, allergic reactions or other clinical emergencies.

Equity must remain central. Testing should not become an advantage limited to people who can pay privately in metropolitan areas. Health services should evaluate whether pathways work for rural and remote Australians, people from culturally and linguistically diverse communities, and Aboriginal and Torres Strait Islander peoples. Culturally safe consent and appropriate communication are essential.

International perspectives can also inform respectful service design. For example, learning how communities engage with unfamiliar health information—even through cultural reporting such as a Morioka fire festival guide—reinforces the value of context, trusted messengers and clear explanations when information crosses language or cultural boundaries.

Pharmacogenomic testing is most effective when it forms part of a coordinated medication safety program. Australian mental health services, researchers and clinicians can strengthen this work through validated testing, careful consent, transparent evidence and follow-up that measures what matters to patients. Practical educational resources, such as those collected by a health sciences network, can also support consistent conversations about medicines and evidence.

Health services can begin by identifying patients with repeated adverse reactions or unsuccessful treatment trials, establishing referral and reporting pathways, and reviewing outcomes over time. Connecting local researchers with GPs, pharmacists, psychiatrists, consumers and carers can turn genetic information into safer, more individualised mental health care.