Would I get results from a HMA if my hair is dyed?
Broadly speaking after six or so washes if it is semi-permanent then testing will be fine. If permanent you really need to wait until the hair grows out at the roots, which is where you will take the sample from.
This is the official line just because it saves clients being concerned about the results.
In research it has only ever been hydrogen peroxide (i.e. bleaching agents) and lead (i.e. blackening agents) that have been found to distort results – also selenium sulphide found in some lightening shampoos. However, we suggest a cautious approach just in case the manufacturers have changed the format of the dye. Your hairdresser should be able to advise on the ingredients in the dye
The client is asked to inform us of the hair colouring used. We don’t compensate for the colouring but note it so that if we get a really “wild card” result we will try and check the ingredients .
In a nut-shell, Dr Watts usually says that it is fine to go ahead and test, but if the client is concerned wait six weeks!
Depending on the type of hair-dye used, you may wish to go ahead right away or wait for a little while. .
