Patch of Gray Hair

Patch of gray hair
Q: I started dying my hair a year ago. I didn't have a lot of gray but enough that I couldn't hide them. I haven't checked my gray since 4 weeks ago when I last dyed my hair, but just today I was absolutely SHOCKED as I noticed that I now have a HUGE patch of all gray hair near the top of my head!
It seems like a large portion of my hair has turned gray overnight. Please help as if the color is causing it, I'll want to stop as soon as possible. Or does getting color on the scalp cause this?

A: The causes of gray hair are somewhat varied, but are predominantly governed by genetics and aging. Each person may respond to stress, hormone changes and other factors in their own way, and for some this can include an increase in developing gray hair. If you are undergoing some significant physical and emotional changes and stresses, it could manifest as an increase in gray hair.
Gray hair could also be a result of physical damage caused by chemical exposure, but in the case of haircolor, there would almost certainly be specific signs of damage (specifically chemical burns) caused by the haircolor chemicals which would cause the melanocytes in the follicles to cease producing pigment.
It isn't unheard of that an individual notes an increase in the amount of gray in their natural color between retouches of artificial hair color, but the cause of the gray is generally not related to the color being applied.
However, if you feel you are experiencing any irritation or sensitivity to the hair color formula you are using, then perhaps you should consult a dermatologist to make certain you aren't developing an allergic sensitivity to the chemicals used, which COULD cause some of the issues you are concerned over.
Photo: Cunaplus/Shutterstock
See also:
The causes of gray hair
Hair and the older woman
How to recognize damaged hair
Gray hair simulator