What is combination skin?

Combination skin is a skin type characterised by an uneven distribution of sebaceous activity across the face.

Typically, the T-zone, namely the forehead, nose and chin, exhibits increased sebum production, leading to a more pronounced shine, sometimes associated with enlarged pores or minor blemishes. In contrast, the cheeks, temples and eye contour tend to be drier and occasionally more prone to tightness.

This duality of combination skin primarily arises from differences in the density and activity of sebaceous glands depending on the area. Indeed, the T-zone has a greater number of sebaceous glands, responsible for sebum synthesis and whose activity is stimulated by hormonal factors, notably androgens, as well as environmental ones. Sebum, composed mainly of triglycerides, wax esters and squalene, plays an essential role in protecting the skin against dehydration and external stressors. However, when produced in excess, it can impart a shiny, glossy appearance to the skin, clog pores and promote the development of blemishes.

In contrast, the cheeks of individuals with combination skin often exhibit a lipid organisation similar to that of dry skin and suffer from a lipid deficiency. For reference, lipids such as ceramides serve as intercellular cement in the stratum corneum, filling the spaces between corneocytes to maintain the cohesion of the skin barrier. They thus limit water loss and protect the skin from external aggressors, for example by restricting the penetration of allergens and micro-organisms. The contrast with the T-zone therefore results from heterogeneity in barrier function across the face.

Discover here our recommendations for caring for combination skin.

The causes of combination skin are multiple and revolve around genetic, hormonal, environmental and behavioural factors. Genetics plays a central role in the distribution and activity of the sebaceous glands, even though, in general, more sebaceous glands are found in the T-zone. Hormonal variations, particularly during adolescence or throughout the menstrual cycle, can also contribute. Androgens, in particular testosterone and its active form, dihydrotestosterone, stimulate the activity of sebaceous glands. The environment also influences the physiology of combination skin. A dry or cold climate favours dehydration and the appearance of dry areas, whereas heat and humidity boost sebum production, increasing shine and blemishes in oily areas. These variations can be seasonal: in summer, excess sebum is more common, while in winter, dry patches prevail.

This was further confirmed by a study conducted on 46 female volunteers aged 21 to 37 that demonstrated skin type can vary with the seasons. The researchers measured sebum secretion separately on the T-zone (forehead, nose and chin) and the U-zone (cheeks and jaw). In summer, 71.7% of the participants exhibited a combination skin profile, compared with less than 50% in autumn (26.8%), winter (41.3%) and spring (34.8%). The study also showed that only 10.8% of the volunteers maintained a skin type homogeneous throughout the year, whereas the majority displayed significant differences in sebum production between the T-zone and the U-zone for at least one season, corresponding to combination skin.

• YOUN S. W. & al. Regional and seasonal variations in facial sebum secretions: A proposal for the definition of combination skin type. Skin Research and Technology (2005).

• MAIBACH H. I. & al. Oily skin: An overview. Skin Pharmacology and Physiology (2012).

• RICHARD M. A. & al. La peau des Français. Analyse des caractéristiques de notre peau à partir de l’étude Objectifs Peau. Annales de Dermatologie et de Vénéréologie (2017).