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A test that shows how your body might react to medication

Article updated on February 8, 2024. 

What if there was a way to understand how you may react to medicine before you even took one pill?

Genetic screening that reveals how your body may respond to prescription drugs makes this possible. It’s called pharmacogenomics and the impact can be powerful. Consider the example of a young man who is diagnosed with depression and prescribed a drug but after several weeks, he doesn’t feel better. The doctor may use trial and error to find a medication that works better — a process that could take months.

With pharmacogenomics, a simple cheek swab for analysis has the potential to reveal  information about which medication may work best for his body. Less trial and error likely means a faster return to normal life.

What is pharmacogenomics?

Pharmacogenomics allows people to understand what type of prescription medication might be most effective for them based on their unique genetic makeup. It can also provide insights into how an individual may react to over the counter medications, such as Tylenol or Advil, and even some supplements.

Individuals process medications uniquely based on their genetic makeup.  In some cases, a person may break down certain medications slowly and for others, the processing may happen too quickly for the medication to take effect. Knowing this information when a new medication is prescribed can help to pick the best one on the first try.

How pharmacogenomics works

Collecting a DNA sample for pharmacogenomic screening can be done easily. If you’re visiting TELUS Health Care Centres in person, a cheek swab can be done at the time of your visit. If you’re doing the test from home, you’ll be sent a kit that allows you to take a cheek swab (a q-tip-like tool). It collects cells from the inside of your cheek, and is then mailed back to the lab.

Once the results are in, you’ll get a detailed report that you can share with your healthcare providers as well as a personalized summary of your results written by our TELUS Health genetic counsellor. The report may be a helpful source of information for conversations with your family doctor and other healthcare providers in the future. You can also share the results with your family members, including your parents, siblings and children. It could give them hints about their own medication response and help them decide if they would like to get a pharmacogenomics test too.

The benefits of pharmacogenomics

Pharmacogenomics has four main benefits:

  1. Potential for faster treatment and feeling better sooner.
  2. Reduced potential for harmful side effects. A fear of harmful side effects are one of the biggest reasons that people stop taking their medications.1
  3. Fewer trials of different medications, which may lower cost spent in time and money.2
  4. Improvement of health issues at the lowest effective dose for many prescription medications.3

This type of genetic testing can be helpful for many different types of medication. At TELUS Health, we offer a pharmacogenomics test that covers more than 150 medications, including those for:

  • Mental illness
  • Pain medications, including opioids and anti-inflammatories
  • Cardiovascular drugs
  • Complex antibiotics

A personalized approach to prescriptions

Pharmacogenomics offers a truly personalized approach to prescribing medications. It’s a way for doctors to remove some of the guesswork out of deciding on a prescription, and for a patient to know they are getting optimal personalized care when it comes to their medication options.
It’s the best way to identify which medicine will be the lowest risk and highest benefit for your body.

Pharmacogenomics is available at TELUS Health Care Centre clinics across Canada. 
For more information, visit

Written in consultation with Corissa Androich, MSc, CCGC, CGC, Certified Genetic Counsellor.

1 8 reasons patients don't take their medications AMA, Feb 22, 2023 

2 Neuropsychiatr Dis Treat. Alejandra Maciel, Ali Cullors, Andrew A Lukowiak, and Jorge Garces, National Library of Medicine, Jan 8, 2018

3 Understanding Pharmacogenomics American Society of Clinical Oncology (ASCO), Jan 2020