Risk factors

Strong

age 12 to 24 years

• Research has shown that 85% of young people between the ages of 12 and 24 years have acne. [5]

genetic predisposition

• The concordance rate for the prevalence and severity of acne among identical twins is high. [11] One study concluded that 81% of variance in acne was attributable to genetics, and only 19% to environmental factors. [12]

greasy skin/increased sebum production

• Sebaceous follicle size and the number of lobules per gland are increased in patients with acne. [8] Androgens stimulate sebaceous glands to enlarge and produce more sebum, which is most prevalent during puberty. Sebum production is fairly high during the first 6 months of life, declines and remains stable throughout childhood, and dramatically increases during puberty.

medications

• Acneiform eruptions can be caused or exacerbated by some medications, including androgens, corticosteroids (topical, oral, or injected), antiepileptic mediations (e.g., dilantin), isoniazid, lithium, and ACTH.

Weak

endocrine disorders

• Patients with endocrine disorders such as polycystic ovary syndrome, hyperandrogenism, and precocious puberty are more likely to have severe acne.

dietary factors

• Few studies have examined the role of diet in acne. Several studies focusing on chocolate consumption found no effect on acne. [15] [16] While Western diet has been associated with increased incidence of acne, these observations are limited by their ability to separate genetic factors from environmental and dietary influences. [17]

female gender/oestrogens

• The role of oestrogen in acne is unclear, but oestrogen is known to decrease sebum production. Many women note worsening of their acne prior to menstruation, and oral contraceptives often help to mitigate this cyclical worsening. Suppression of sebum production requires higher doses of oestrogen than does suppression of ovulation. [18]

obesity/insulin resistance

• Insulin and insulin-like growth factor (IGF) can stimulate keratinocytes and sebaceous glands. Elevated IGF-1 levels are found in women with post-adolescent acne, [19] and obesity has been found to be associated with an increased prevalence of acne in people aged 20 to 40 years. However, no association between obesity and acne was found in patients aged 15 to 19 years. [20]

hyperandrogenism

• The rise in circulating androgens at the onset of puberty is associated with increased production of sebum and the development of comedonal acne, but most patients with acne have normal androgen levels. Rare cases may be associated with pathologically elevated androgen levels due to an underlying disorder, such as polycystic ovary disease.

halogenated aromatic hydrocarbons exposure

• Occupational or environmental exposures to halogenated aromatic hydrocarbons exposure (e.g., chlorinated dioxins and dibenzofurans) can cause chloracne.