Graying is said to have occurred prematurely if seen before 20 years in Caucasians or before 30 years in Africans.[1] Few authors have suggested that 25 years can be used as a cutoff for people in the Indian subcontinent.[21] Canities is mainly a clinical diagnosis. Some authors suggest investigations involving serum Vitamin B12, folic acid, and thyroid levels to be conducted in individuals with no family history of premature graying.[65] The role of trichoscopy in canities remains to be explored.

There is no single widely recognized standard scoring system to determine the severity of PGH. Attempts have been made to classify graying as mild, moderate, and severe based on percentage of hair involved, number of hair involved, or percentage of hair affected in various areas of the scalp. These grading systems used questionnaires and clinical examination to assess the severity of graying.[38],[43],[66],[67],[68]

Although many patients visit dermatology outpatient for the treatment of PGH, very few treatment options are satisfactory. The treatment for PGH should be directed to address the cause. Vitamin B12 deficiency and hypothyroidism are reversed with vitamin and hormone replacement, respectively. Plucking of gray hair is an easy option for individuals with <10% affected the scalp hair.[65] Most of the individuals must rely on hair colorants for the restoration of hair color.[69] Hair colors can be prepared from natural products or can be synthesized artificially. They can be temporary or permanent colorants. Commonly, natural hair dyes are prepared from Indian gooseberry (Emblica officinalis), false daisy (Eclipta alba), and lotus tree (Zizyphus spina-christi) and Henna (Lawsonia alba). The advantage of natural hair dyes is that they are hypoallergenic and nontoxic.[70] Permanent hair dyes are the most popular in the commercial market. There is a risk of damage to the hair shaft due to oxidation with permanent hair dyes. Temporary hair dyes do not penetrate the cuticle and wash out with shampooing.[71] Hair dyes not only help camouflage but also protect gray hair from photodamage.[72] Some individuals experience irritant dermatitis (commonly due to p-phenylenediamine) and hair loss due to hair coloring.[73]