Fentanyl and its analogues are the adulterant most likely to turn a night into an emergency, and a strip is the simplest way to check for them. Cheap, small, and worth carrying.
What we rate
Clear lines, sensible instructions, and honest labelling about what the strip can and cannot catch. Technique matters, dilution especially, so read the directions before you need them.
What it will not do
Rule out every analogue, or tell you anything about dose. It is a yes or no safety check, not a full analysis. Know the warning signs on our emergencies page.
Information, not medical advice. Threshold does not promote or encourage MDMA use. This exists so that people who make their own choices can make safer, better-informed ones. It is not a substitute for professional care.