Sebum Output as a Factor Contributing to the Size of Facial Pores

M. Roh; M. Han; D. Kim; K. Chung


The British Journal of Dermatology. 2006;155(5):890-894. 

In This Article


Enlarged facial pores are one of the most common cosmetic problems in Asian female adults and patients frequently ask for a treatment to reduce the size of the pores. Although various factors are known to cause enlarged pores such as sex, genetic predisposition, ageing, chronic ultraviolet light exposure, comedogenic xenobiotics, acne and seborrhoea, no study results are available that show a significant relationship of these factors with the enlarged pores. Previous reports regarded enlarged pores as a phenomenon of photoageing[13,14,15,16,17] and treated enlarged pores using methods such as intense pulsed light, retinoic acid cream, oral isotretinoin, isotretinoin iontophoresis and glycolic acid peeling. Some reports briefly mentioned the pore size reduction effect while focusing on the acne scar treatment.[18,19] While it is true that enlarged pores are one manifestation of photoageing, many patients with enlarged pores do not necessarily show other photoageing phenotypes such as sallow skin tone, dilated pore structure, crepe-paper-like inelasticity of the eyelids and rhytids.[20] Instead, many patients with enlarged pores seem to complain of greasy or oily skin compared with other patients with normal pore size. The appearance of skin oiliness results from the presence of an excess of sebum secreted by the sebaceous gland onto the skin surface. On the face, oily skin is shiny and may be accompanied by large pores, follicular plugs, sebaceous filaments, keratotic plugs and comedones.

This study was intended to determine the factors that contribute to the formation of enlarged pores. The significance of sebum output, age, sex, hormonal factors and severity of acne were evaluated. The mean sebum output level was significantly higher in males than in females and the sebum output level slightly increased with age in our study. However, sebaceous gland activity is known to decrease with advancing age[4] and it falls by approximately 40% in the sixth decade in females and in the seventh decade in males.[5] As our study group consisted of men and women aged from 20 to 40 years old, it may be possible that our participants were not old enough to show ageing effects. The pore size was significantly larger in females than in males, and the pore size slightly decreased with age in our group. However, the decrease of pore size with age was not statistically significant. Using multiple linear regression analysis, we found a significant correlation between pore size and sebum output level, sex and age (r = 0·45, P < 0·05). Among the independent variables, sebum output level (P < 0·001, t = 8·17) was the most significant factor correlated with the pore size compared with sex (P < 0·001, t = 4·37) and age (P = 0·03, t = −2·21). Although age affects pore size, it has the least influence of the factors studied in determining pore size. Also, it is difficult to conclude whether it has a positive or negative correlation with pore size from our data alone. In comparing males and females, males showed a higher correlation between sebum output level and pore size (males: r = 0·47, females: r = 0·38) which led us to analyse additional factors that may influence the pore size in females. The major difference between the two sexes is that the hormonal factors of the monthly menstrual cycle in females are known to influence sebum production.[8,9] In our study, during the menstrual cycle, the sebum output level was significantly higher and the pore size was larger in the ovulation phase. This suggests a relationship between the two sets of values but the exact mechanism of the hormonal regulatory effect on these values is not known. The menstrual cycle is regulated by several hormones: luteinizing hormone and follicle-stimulating hormone, which are produced by the pituitary gland, and oestrogen and progesterone. However, very little is known about the role of female hormones in modulating sebum production. Oestrogen given systemically in sufficient amount will decrease sebum production but the dose required to suppress sebum production is greater than the dose required to suppress ovulation.[21] The ovulation phase begins with a surge in luteinizing hormone and follicle-stimulating hormone levels. Luteinizing hormone stimulates ovulation and the oestrogen level peaks during the surge; the progesterone level also starts to increase. As oestrogen in physiological doses has a minimal effect in regulating the sebaceous gland, the surge of luteinizing hormone and follicle-stimulating hormone along with the increase of progesterone may have an effect in activating sebaceous gland activity during the ovulation phase. Multiple linear regression analysis demonstrated higher correlation when the menstruation cycle was added as an independent variable (r = 0·38 r = 0·43). We also analysed prior severity of acne in all participants, but the severity of acne did not correlate with the pore size in either sex.

In conclusion, increased pore size was significantly associated with increased sebum output level and also with sex and age. Among the variables, sebum output level correlated most significantly with the pore size; males showed higher correlation than in females. In females, pore sizes were significantly larger in the ovulation phase of the menstrual cycle but the severity of acne did not correlate with the pore size in either of the sexes. Our study clearly shows that the sebum output level affects the size of facial pores and that a treatment focused on reducing sebum production may be beneficial in decreasing enlarged pore sizes.

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