A young man in a hooded jacket walking toward the bright end of a dark tunnel

Pharmacogenetic testing improves depression treatment in youth and reduces suicide risk

Ruslan Dorfman, PhD, MBA4 Nov 2026

If your child or teen has been diagnosed with depression, you may be worried about treatment, especially about antidepressants and suicide risk. Depression in young people is treatable, and both psychotherapy and medication can help. Antidepressant labels carry a warning about suicidal thoughts in young people, so any decision to use one balances that risk against the serious risks of untreated depression. Pharmacogenetic (PGx) testing adds important information: it shows how your child’s body breaks down specific antidepressants, which can help choose a safer medication and dose from the start.

If you are worried about suicide right now: call or text 9-8-8, the Suicide Crisis Helpline, available 24 hours a day across Canada in English and French. Young people can also reach Kids Help Phone at 1-800-668-6868 or by texting CONNECT to 686868. In an emergency, call 911 or go to the nearest emergency department.

How is depression treated in children and teens?

The 2023 guideline from the American Academy of Child and Adolescent Psychiatry supports two main treatments: psychotherapy, especially cognitive behavioural therapy (CBT) and interpersonal therapy, and selective serotonin reuptake inhibitor (SSRI) antidepressants. Fluoxetine and escitalopram have the strongest evidence in young people. Milder depression is often treated with psychotherapy first, while moderate to severe depression may need medication as well.

Do antidepressants increase suicide risk in young people?

Health Canada and the U.S. Food and Drug Administration require antidepressant labels to warn about a possible increase in suicidal thoughts and behaviour in children, teens and young adults. This warning is based on clinical trials: in an FDA analysis of 24 trials with more than 4,500 young people, about 4% of those taking an antidepressant had suicidal thoughts or behaviour, compared with about 2% of those taking a placebo. There were no suicides in these trials.

Untreated depression is itself a major risk factor for suicide. The warning does not mean antidepressants should be avoided, but that young people starting a medication or changing a dose need close follow-up, especially in the first weeks. Watch for new or worsening depression, agitation, irritability, unusual changes in behaviour or talk of self-harm, and contact the doctor right away if you notice them.

What did the Danish study find about genes and suicide risk?

A large Danish study followed 17,297 young people with depression for one year after they started (es)citalopram, sertraline or fluoxetine, and compared outcomes by their CYP2C19 and CYP2D6 metabolizer status:

Children and teens taking (es)citalopram who were CYP2C19 poor metabolizers had 2.67 times the rate of suicide attempt or self-harm and were 1.64 times more likely to switch medication than normal metabolizers. The authors found a U-shaped pattern, with ultrarapid metabolizers also showing a trend toward a higher rate of suicide attempt or self-harm.
Young adults (19 to 25) taking sertraline who were CYP2C19 poor metabolizers were about twice as likely to switch medication.
Young adults taking fluoxetine who were CYP2D6 poor metabolizers had more than three times the rate of psychiatric emergency department visits.
In adults over 25, no associations were statistically significant, although the same U-shaped pattern with (es)citalopram was seen.

Poor metabolizers build up high drug levels, which can cause side effects such as agitation and restlessness. In ultrarapid metabolizers, the medication may be cleared before it can work. This lack of response can go unnoticed for weeks, without the side effects that would lead to an emergency visit, while depression remains untreated.

The authors estimated that testing about 463 children before starting (es)citalopram could prevent one suicide attempt. They concluded that pharmacogenetic testing is particularly useful in younger people. Because this was an observational study, it shows associations rather than proof that testing prevents suicide attempts, but it adds to the evidence that genetic results matter most in young patients.

Why does accurate genetic testing matter?

The Danish study used a genotyping array that tested a limited set of variants. A more complete test could give even more useful results:

Sertraline is broken down by both CYP2C19 and CYP2B6, but the study looked only at CYP2C19. In a study of 840 patients, people who were poor metabolizers for both enzymes had sertraline levels 189% higher than normal, while people with fast versions of both enzymes had levels about 35% lower. CPIC now uses both genes for sertraline dosing.
Fluoxetine, paroxetine and some other antidepressants are affected by CYP2D6. Some people carry extra copies of the CYP2D6 gene, which speed up drug clearance, or are missing a copy, which slows it down. The array used in the Danish study did not measure these copy number variations.

Pillcheck measures CYP2D6 copy number variations and reports CYP2D6, CYP2C19, CYP2B6 and other genes that affect antidepressants. Read more about how accurate pharmacogenetic testing is.

What other antidepressant options are there?

If a first antidepressant does not work or causes side effects, there are other options. Each antidepressant is affected by different genes, so genetic results can help choose the next one. Bupropion (Wellbutrin), which was not included in the Danish study, works differently from SSRIs, is less likely to cause weight gain and is partly converted by CYP2B6 into an active form. It is used off-label in teens with limited evidence, and it strongly blocks CYP2D6, which can raise the levels of other medications. Psychotherapy remains an important part of treatment, especially to prevent relapse once symptoms improve. Read more about medication or therapy for depression and how DNA testing can help find the best anxiety and depression medication.

How can a Pillcheck test help?

A Pillcheck test includes a medication review by a clinical pharmacist, who considers your child’s age, genetic results and past medication experience. Parents can order the test for a child, and young adults can give their own consent and access their results. The sample is collected at home with an easy-to-use kit. In a Canadian randomized trial in community pharmacies, people with depression or anxiety whose antidepressant treatment was guided by pharmacogenetic results improved more than those who received standard treatment.

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, and report updates are free of charge. Learn about reimbursement for pharmacogenetic testing.

Summary

Psychotherapy and SSRIs such as fluoxetine and escitalopram are the main treatments for depression in young people.
Antidepressants carry a warning about suicidal thoughts in young people, so close follow-up is needed, especially in the first weeks. Untreated depression is also a serious risk.
In a large Danish study, children and teens who were CYP2C19 poor metabolizers had a higher rate of suicide attempt or self-harm on (es)citalopram, with a similar trend in ultrarapid metabolizers.
Accurate testing of CYP2C19, CYP2B6 and CYP2D6, including copy number variations, matters for sertraline, fluoxetine and other antidepressants.
Parents and doctors should consider pharmacogenetic testing before starting an antidepressant in a child or teen.
If you are worried about suicide, call or text 9-8-8 at any time.

Frequently asked questions

Are antidepressants safe for teenagers?

SSRIs such as fluoxetine and escitalopram can be effective for teens with depression. They carry a warning about suicidal thoughts, so teens need close follow-up, especially in the first weeks and after dose changes.

Can a genetic test prevent suicide?

No test can prevent suicide on its own. Genetic testing helps choose a medication and dose that suit your child’s body, which may lower the risk of side effects and of an ineffective first treatment. Close follow-up and support remain essential.

Can I order a Pillcheck test for my child?

Yes. Parents can order the test for a child, and the sample is collected at home with an easy-to-use kit. Young adults can order their own test.

What should I do if my teen talks about suicide?

Take it seriously. Call or text 9-8-8 for support at any time, contact your teen’s doctor, and call 911 or go to the nearest emergency department if they are in immediate danger.

See how Pillcheck helps you and your health care provider choose the right mental health medications: