Paper fentanyl test strips are a simple way for people struggling with substance use to determine if fentanyl has been mixed into their drugs, but some advocates say they fail to help the people most at risk of dying from an opioid overdose.

The tests are low-cost and easy to use. Working similarly to a COVID-19 rapid test, a user mixes a very small amount of the drug they want to test with water, and dips the paper test strip into the solution.

"Then you wait for the result so then on your little test strip," Karen McDonald, head of Toronto's Drug Checking Service, told CTV's Your Morning on Tuesday. "One line will present if your drug is positive for fentanyl, two lines will present if your test is negative for fentanyl."

However, McDonald – who has 15 years of public sector experience, including in health policy – said the tests aren't beneficial to people who are addicted to opioids and knowingly taking fentanyl. Someone who has no intention of using opioids and detects the presence of fentanyl in their supply of a different drug would likely alter their consumption in response, she said, but these types of contamination cause the minority of opioid overdoses.

For people who intentionally use opioids, knowing their drugs contain fentanyl is a very small piece of the harm-reduction puzzle.

"For over five years now, fentanyl has really saturated the unregulated opioid supply and is really the opioid of choice for most folks using opioids at this point," McDonald said. "So, simply knowing if there is fentanyl in their fentanyl doesn't really add value for folks."

McDonald said people who knowingly use opioids benefit more from knowing how much fentanyl is in their supply so they can avoid an overdose, and from knowing about trace amounts of other harmful substances, such as the veterinary tranquilizer xylazine, contaminating their supply.

According to the Government of Canada’s Health Infobase, 5,360 Canadians died from opioid overdoses between January and September last year. To make a significant impact on the number of opioid-related deaths in Canada, McDonald said more people need to have access to more advanced testing technology.

"The opioid supply is constantly changing, so sadly, very sophisticated technologies are required," she said.

In 2018, Health Canada invested in new lab-based testing technology that can provide potentially life-saving information about which substances, at which strengths, are contaminating a drug sample. McDonald's organization offers this type of testing, and she wishes more people in Canada had access to it.

"We are able to provide a comprehensive list of all of the many drugs that are present in a sample. We can also quantify how much of some of those drugs are present so folks can use that information to make dosing decisions," she said.

"So that's really the type of drug-checking technology we need to be striving for if we want those at highest risk of overdose to avoid death or other harms."