What to Do After a Positive Result

Before deciding what to do with a fentanyl-positive substance, ensure that naloxone is physically present and accessible. Naloxone (brand names Narcan, Kloxxado, RiVive) is an opioid antagonist that can temporarily reverse a fentanyl overdose. It is available over the counter at most pharmacies and free through many harm reduction programs. If you or someone nearby uses a substance that tested positive for fentanyl, naloxone should be within arm\'s reach — not in another room, not in a bag, not in a car. Seconds matter during an overdose.

The single most effective overdose risk reduction behavior is having another person present who can administer naloxone and call 911 if needed. Research published in JAMA Network Open in 2025 found that people who regularly use fentanyl test strips were significantly more likely to use with others present. If no one is physically available, the Never Use Alone hotline (1-800-484-3731) connects callers with trained operators who stay on the line during use and dispatch emergency services if the caller becomes unresponsive.

If you choose to use a substance that tested positive for fentanyl, use a significantly smaller amount than you normally would. Fentanyl is active at microgram doses — far less than most other opioids. A \'tester shot\' or \'tester bump\' using a fraction of the intended amount allows you to gauge potency before committing to a full dose. Wait at least 10-15 minutes after a test dose before using more. Many fatal overdoses occur because users take a second dose before the first has fully taken effect.

Combining fentanyl with other central nervous system depressants — alcohol, benzodiazepines, gabapentin, muscle relaxants, or other opioids — dramatically increases overdose risk. Polysubstance use is involved in the majority of overdose deaths. If a substance tests positive for fentanyl, avoid combining it with anything else that slows breathing.

An opioid overdose typically presents as: slow, shallow, or stopped breathing; blue or gray lips and fingertips; pinpoint pupils; unresponsiveness to stimulation (sternal rub, shouting); gurgling or snoring sounds. If you observe any of these signs: call 911 immediately, administer naloxone (one spray in one nostril or one intramuscular injection), place the person in the recovery position (on their side), and administer a second dose of naloxone if there is no improvement after 2-3 minutes.

In many regions, the fentanyl contamination rate is so high that nearly every sample will test positive. This does not make testing pointless — it makes it essential. A positive result confirms fentanyl is present, which should trigger the risk reduction behaviors described above. An occasional negative result — a substance that does not contain fentanyl — is valuable information that changes how you dose and what precautions you take. Testing also detects the presence of specific analogs (when using broad-spectrum tests like Subcheck) that may indicate higher potency, which changes the calculus on dosing.

Organizations distributing fentanyl test strips should pair every strip with clear post-test guidance. Include printed cards with result interpretation and risk reduction steps. Train outreach workers to have brief, nonjudgmental conversations about what to do with results. Co-distribute naloxone with every FTS distribution. The test strip is only as useful as the action it enables — without post-test guidance, a positive result is just information without a plan.