Dosetest Fentanyl Test Strips

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Check if your drugs contain fentanyl by using Dosetest Fentanyl Test Strips.

  • Contains one single use strip
  • Tested by third party labs
  • Reacts to over 20 different Fentanyl variants

The most sensitive, cost-effective, and accessible method for checking if your drugs contain fentanyl is by using Fentanyl Test Strips. With just a strip and a few minutes you can identify Fentanyl, protecting yourself and your friends from the dangers of a toxic drug supply.

What exactly are Fentanyl Test Strips?

This type of test is called a “lateral flow competitive immunoassay”, and it’s pretty much the reverse of a rapid COVID test or pregnancy test. The strip is pre-loaded with “control particles” and when you dip it into your sample, the water carries these particles along with the drug towards the testing lines. If there’s no fentanyl the control particles will bind to the testing line, causing it to become visible, but if there is then the fentanyl will bind instead and the line won’t appear.

Who is Dosetest?

DoseTest is a worldwide social enterprise which provides reagent testkits and fentanyl test strips as widely and cheaply as possible. You can find them at @dosetest on Twitter or @dosetestofficial on Instagram for a regular dose of information about testing, harm reduction and the world of drugs.

How do I use the test strips?

Use the Dosetest app in 3 steps

1. Use the Dosetest app to receive personalised guidance on how to test your sample with your strip.

2. Mix up your sample and test it, following the steps in the app.

3. Key in the results so that the app can help you interpret them.


Non-app method

We recommend you utilise the Dosetest app, but we do have instructions below here.

1: Prepare your sample

Pills and powders: If testing a pill, break off a small chunk and crush it as finely as you can. If it’s a powder, chop it up and mix it as best you can. These strips are highly sensitive, so you only need about 5 milligrams (think a couple of grains of salt). Put this into a cup, add 5ml (about a teaspoon) of water and mix them together. Fentanyl dissolves pretty easily, so don’t worry if there is some residue after you’ve stirred it a bit – that won’t affect the results.

(Note: MDMA and methamphetamine can cause false positives. To avoid this, add an extra 4 tsp water to the sample so that it is more diluted. IPPH and DPH can also cause false positives, but are far less common).

Liquid: If you’re prepping a shot, do that first – the residue left in the preparation container is all you need. Add about 5ml of water (about a teaspoon), then put the mix into a cup. If it’s in a vial/bottle, shake it a little and put a drop into a cup, then add the teaspoon of water and mix.. If you are testing a pressed tablet or pill, using a clean knife, break off a small part and crush it into a powder. If your substance is already in the form of a powder, mix it as thoroughly as possible.

2: Running your test

Take the strip out of its packaging, then dip the end with the wavy lines into your sample for about 15 seconds. Once that’s done, place it horizontally on a nice clean surface and wait for up to 3 minutes for your results to appear.

3: Interpreting your test

Since there are 2 lines which would either appear or not appear, there are 4 possible results. The line nearer the end that you dipped is the Test line, and the line nearer the handle is the Control line.

Control line visible, Test line invisible: This is a positive result, which indicates that your sample DOES contain fentanyl.

Control line visible, Test line visible: This is a negative result, which indicates that your sample DOES NOT contain fentanyl.

Control line invisible: Regardless of what the Test line does, this means that something has gone wrong and the result is inconclusive – we don’t know if your sample contains fentanyl. We advise repeating the test or, if that isn’t possible, assuming that the sample DOES CONTAIN fentanyl.

More information

Scally, C., 2021. How do testkits work?. [online] Available at