Limitations of test strips to check illegal drugs for dangerous substances

Use every precaution, even if you or your friends use fentanyl or xylazine test strips:

• Never consume alone.
• Consider consuming a smaller dose: start low and go slow.
• Don't mix opioids with alcohol or other drugs.
• Go to a supervised consumption site if your community has one.
• Carrynaloxone, which can temporarily reverse an opioid overdose. Make sure that you, and the people with you, know how to administer it.
• Call 9-1-1 or your local emergency help line if you think someone is having a drug overdose.
• Get your opioid overdose wallet card and carry it with you. Know what to do.

Limitations of test strips for illegal drugs

Test strips, whether they are a medical device or not, can provide false negatives. A false negative result means that the test strip did not detect a targeted drug even though the drug was present in the sample. This could lead to a false sense of security, resulting in overdose or death.

There are many reasons test strips may not detect all drugs present:

• The test strips may only be able to detect certain substances, such as xylazine or fentanyl, and not other toxic substances that might be present, like carfentanil.
• Illegal drugs can be mixed unevenly with other substances, so the portion tested may not contain the same amount of the drug as that which is to be consumed.
• Other substances mixed in the sample could interfere with the accuracy of the test.
• The sample size tested may be too limited to detect a specific substance.

Health Canada is working with companies of authorized products to include warnings on the packages of test strips that detect the presence of xylazine, fentanyl and/orits analogs to better inform consumers about the risks of unreliable results when using the test strips to check the illegal drugs they plan to consume.

For more information:

• Health Canada is advising Canadians of the potential limitations when using test strips to detect fentanyl (December 13, 2017)
• Health Canada reminds Canadians of the limitations of fentanyl test strips being used to check street drugs before consumption
• Signs of an Opioid Overdose
• Naloxone
• Canadian Pharmacists Association: Naloxone Made Easy (video)