Skin function and appearance is modified by a range of factors.

Neural pathways act on eccrine glands to moderate body temperature in warm conditions by stimulating sweat secretion. Hormones influence sebum secretion, while the skin flora can moderate the barrier function and immune response. A change in the commensal bacteria in skin flora can trigger a T-cell immune response leading to inflammation. Increased sebum levels may also lead to inflammation.2,3

Genetics may influence the amount of keratin produced or the extent of hair production, which can also be modified by hormones. An autoimmune response is involved in stimulating keratinocyte turnover in psoriasis. Cell turnover, with cell death or apoptosis, can also be regulated by hormones, growth factors and cytokines.1,4,5

Environmental factors such as temperature, UV light, humidity, exposure to chemicals or topical preparations can also influence skin barrier proprieties or cell proliferation.

Common causes of blocked pores include:

·       infection entering the pore, due to an imbalance in the skin flora (eg pustules, boils)

·       too much keratin meaning horny cells block the follicle (eg keratosis pilaris)

·       overactive sebaceous glands (eg acne, seborrhoeic dermatitis)

·       ingrowing hair causing inflammation (eg pseudofolliculitis barbae)