Grey hair, or “canities”, is simply the absence of colour, resulting from the loss of pigment (melanin) that gives hair and skin their colour. When and why hair turns grey is a little more complex.

Causes of Greying Hair

Aging is the main cause of greying hair, but health and heredity can also be factors. With age, the body produces a reduced amount of melanin. Hair grows out of hair follicles, which contain cells – called “melanocytes” – filled with melanin. Over time, as hair follicles produce less melanin, the new hair grows out lighter in colour.

Genetics plays a role too. If your parents went grey early, you are more likely to see the same pattern. Premature greying in one’s teen years, has also been associated obesity, smoking and rare genetic syndromes. Conditions such as pernicious anemia, thyroid disorders, and osteopenia have been reported present in patients with early onset of grey hair, but on an inconsistent basis.

Vitiligo is an autoimmune condition where there is loss of skin pigmentation through death of the melanocytes. This can also cause hair of the scalp, eyebrows, eyelashes and body to lose its pigment, in some cases.

Facts About Greying Hair
  • Men start to go grey earlier, at about age 30; women at around 35.
  • Grey hairs first appear around temples and top of the head.
  • Grey hair is not truly grey in colour. It is a mixture of the remaining hair pigment and white hairs. White hair is also an optical effect; keratin in hair actually has a yellow colour, however light reflects back to the eye and creates a white appearance for the hair.


  1. Grey Hair Article
    JAm Acad
     2015 Feb;72(2):321-7\