Most detox shampoos and test shampoos do work and they can remove unwanted hair toxins that can be detected by a hair drug test. The drug toxins and drug metabolites are circulated throughout the body via the blood stream. The blood feeds the hair while it grows. As the hair is formed the toxins are trapped inside the hair follicle.

During the hair drug test procedure, a minimum inch and a half long hair sample is clipped from the back of the head near the scalp by the examiner. This allows the test to reveal a minimum 90 day drug history. If the scalp hair is shorter than an inch and a half long, the examiner may look for other areas on the body to take a suitable sample. Body hair grows much slower then scalp hair so a smaller sample can be taken, this will also allow the test to reveal drug history much further than 90 days. About 40 to 120 hair fibers are usually collected for this test.

Once sent to a laboratory the hair is dissolved with organic solvents. Once in a liquid solution, the toxins are freed from within the hair follicle. An extraction is performed on the liquid and drug toxins are removed. Once the drug metabolites are isolated a GC/MS is performed just like with urinalysis testing.

Detox shampoos work by coating the hair with an organic film, much like a conditioner does. When the examiner removes the hair sample the shampoo bound to the hair goes with it. Once the hair is dissolved, the residual left by the shampoo is free to interact with the drug metabolites, which are trapped in the hair follicle, making the toxins undetectable by the drug test. This is way there is a 10 hour window for shampoos, like conditioners, they will eventually wear off and loose effectiveness.