What causes hair loss after permanent hair dyeing?

What causes hair loss after permanent hair dyeing?

Hair loss after hair dyeing is common due to the manipulation of the hair shafts during the dyeing procedure.  Permanent dyeing involves rubbing the dyestuffs into the hair and scalp and then rubbing the hair and the scalp with rinsing with water to remove the extra dye.  A conditioner is then rubbed onto the hair to decrease hair shaft swelling and neutralize hair pH followed by rinsing again.  This is four rubbing and rinsing sequences that will easily remove any telogen hairs that have loosened.

There are other instances, however, where hair dyeing can precipitate hair loss due to hair shaft weakening.  Hair dyeing requires hydrogen peroxide to swell the cuticular scale and open up ports for the permanent dyestuffs to enter the hair shaft and undergo the oxidation/reduction reaction required for production of the artificial hair color.  These openings are somewhat closed when the ph neutralizing hair conditioner is applied following dyeing to reverse the hair shaft swelling, but the hair shaft remains more porous than virgin hair.  This porosity results from and precipitates further protein loss weakening the hair over time with continued washing and grooming.  The porosity of the hair shafts is increased when the hair is bleached or lightened.  This is why brown hair dyed blond tends to experience more hair loss from breakage than brown hair dyed brown.  The amount of peroxide and ammonia in the hair dye will determine the degree of hair weakening and subsequent loss.

Thus, the hair loss experienced after permanent hair dyeing is due to hair breakage and not hair loss, but patients find it difficult to make this distinction.  All the patient knows is that their hair is getting thinner and more is appearing in the sink.  It important for the dermatologist to have this patient bring in 4 consecutive days of hair loss.  The bag should be examined for hairs that have an intact bulb.  If less than 50% of the hairs have a hair bulb, hair breakage is the reason for the hair thinning and alterations in hair grooming are in order to solve the problem.  Even though there are many salon and consumer treatments for hair breakage, the best advice is to do as little as possible to the hair.  Minimize combing, brushing, dyeing, perming, straightening, and styling to traumatize the hair as little as possible.  The advice is almost too simple for most patients to believe.

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