Laboratory technician in protective glasses and gloves loading DNA samples into a genetic testing instrument

Can genetic testing help me to choose psychiatric medications?

Ruslan Dorfman, PhD, MBA30 Oct 2026

Finding the right psychiatric medication often takes several tries. Pharmacogenetics (PGx) can provide valuable information about which medications and doses are more likely to suit you, based on how your body metabolizes and reacts to them. This article explains what psychiatric genetic tests look at, what expert guidelines recommend and what the research shows.

What do pharmacogenetic tests for psychiatric medications look at?

Pharmacogenetic tests look at two types of genes:

Pharmacokinetic genes – genetic variations that directly affect how a drug is metabolized and cleared, and therefore its levels in the blood. Examples are CYP2D6 and CYP2C19.
Pharmacodynamic genes – variations in brain receptors and other proteins that the drug targets or triggers, such as the serotonin transporter gene (SLC6A4) and the serotonin receptor gene HTR2A.

Each test provider selects a different set of genetic markers to analyze. Some commercial psychiatric tests combine pharmacokinetic and pharmacodynamic genes and apply their own rules to interpret the results. Because providers use different markers and rules, results and recommendations can differ from one test to another, which can leave doctors wondering which one is correct.

Do drug labels include genetic information for psychiatric medications?

Yes. The effect of genetic variations on drug metabolism and clearance is well established. Regulatory agencies, including Health Canada, the US Food and Drug Administration (FDA) and the European Medicines Agency, include information in drug labels on how genetic variations affect drug exposure and clinical response and increase the risk of side effects. Some labels also include genotype-specific dosing limits.

What do expert guidelines recommend?

The Clinical Pharmacogenetics Implementation Consortium (CPIC), an international group of experts, reviewed the evidence for both pharmacokinetic and pharmacodynamic genes to provide consistent recommendations on interpreting and using genetic test results for antidepressants. Its 2023 guideline for serotonin reuptake inhibitor antidepressants:

gives dosing and drug selection recommendations based on CYP2C19 (for example, citalopram, escitalopram and sertraline), CYP2D6 (for example, fluvoxamine, paroxetine and vortioxetine) and CYP2B6 (sertraline);
found insufficient evidence to make recommendations based on the pharmacodynamic genes SLC6A4 and HTR2A.

An international consensus from the International Society of Psychiatric Genetics similarly supports testing CYP2C19 and CYP2D6 to guide the selection and dosing of several commonly used antidepressants and antipsychotics. It also supports HLA testing before some mood stabilizers, such as carbamazepine, oxcarbazepine and phenytoin (see the FAQ below).

The Pillcheck test includes the CPIC-recommended genes and reports according to CPIC guidelines.

How can genetic testing help with psychiatric treatment?

This information can be important to discuss with your healthcare provider if you're considering genetic testing for psychiatric medications. Many doctors are concerned about drug-induced side effects and use a "start low, go slow" approach to dosing. While this is often appropriate, it can leave people in a mental health crisis waiting longer for their treatment to reach an effective dose.

Pharmacogenetic testing for CYP2C19, CYP2D6 and CYP2B6 shows which medications your body is likely to eliminate too quickly or too slowly. With this information, your doctor can choose a medication that is less likely to cause side effects and more likely to be effective, and reach the right dose sooner. This can shorten the trial-and-error process of finding the right medication.

What does the research show?

Remission. In a meta-analysis of 13 controlled trials with 4,767 patients with major depression, people whose antidepressant treatment was guided by pharmacogenomic testing were about 41% more likely to reach remission than those receiving usual treatment.
A Canadian trial using Pillcheck. In a randomized controlled trial in community pharmacies, people whose treatment was guided by Pillcheck improved about twice as much in depression, anxiety and disability over six months as those receiving usual care. Read more about this trial.
The largest trial so far. The PRIME Care trial randomized 1,944 US veterans with depression at 22 Veterans Affairs medical centres. When clinicians had pharmacogenomic results, 59% of patients received an antidepressant with no predicted drug-gene interaction, compared with 26% with usual care, and remission rates over 24 weeks were higher. A later analysis of the same trial found that patients whose treatment was guided by pharmacogenomics reached remission and response sooner, and that this benefit held steady over six months.

Who can help interpret the results?

Not all doctors are familiar with pharmacogenetics. Pharmacists trained in pharmacogenetics can help interpret DNA test results in the context of your medication history and past experience. The Pillcheck service includes such a medication review, which is especially helpful for people living with mental health conditions who are looking for a more personalized treatment option.

Pillcheck testing is performed in CAP- and COLA-accredited clinical genetic laboratories located in Canada. Pillcheck reports on 24 genes, increasing coverage with new guidelines and drug labels (see the genes tab), and covers 355 medications, which account for over 70% of dispensed prescriptions. The Pillcheck test panel ensures high accuracy for people of non-European and admixed ancestries. Your results last a lifetime, report updates are free of charge, and it's easy to share your results with your doctor.

Is pharmacogenetic testing covered by insurance?

Many insurance providers in the US and Canada (such as Canada Life and Medavie Blue Cross) include this testing in their plans or will reimburse you through Healthcare Spending Accounts (HCSA). Consider Pillcheck as a preferred option and discuss it with your healthcare provider.

Summary

Pharmacogenetic tests look at pharmacokinetic genes, which affect drug levels, and pharmacodynamic genes, which affect drug targets.
CPIC guidelines support using CYP2C19, CYP2D6 and CYP2B6 results for antidepressants, but found insufficient evidence for SLC6A4 and HTR2A.
Pharmacogenomic-guided treatment was about 41% more likely to lead to remission in a meta-analysis of 13 trials, and a Canadian trial using Pillcheck found about twice the improvement in depression, anxiety and disability.
In the large PRIME Care trial, test results helped clinicians avoid drug-gene interactions, and patients reached remission sooner.
A pharmacist medication review helps put results into practice.

Frequently asked questions

Can a genetic test tell me which antidepressant will work?

No test can guarantee that. A pharmacogenetic test shows how your body is likely to process many medications, which helps your doctor choose a medication and dose with a better chance of working and fewer side effects.

Should I stop or change my medication based on my results?

No. Never stop or change a psychiatric medication on your own. Discuss your results with your prescriber, who will consider them together with your symptoms, history and other medications.

Do I need to repeat the test?

No. Your genes don't change, and your Pillcheck report is updated free of charge as new guidelines and medications are added.

Does Pillcheck report HLA genes?

No. HLA genes are linked to rare but serious allergic reactions to some medications, including the mood stabilizers carbamazepine, oxcarbazepine and phenytoin. We don't include HLA results because they can easily be misread: carrying a risk variant doesn't mean you will react, and not carrying a known variant doesn't mean you're safe, because many risk variants are not yet known or tested. Whatever your results, watch for a rash, fever, blistering or mouth sores after starting a new medication, and contact a healthcare provider right away if they appear. If your doctor recommends HLA testing, they can order it through a clinical lab.