Facial hair growth patterns vary significantly among individuals. Many people notice their mustache hair does not grow uniformly, with some areas appearing sparser. This often includes the central region of the upper lip, commonly referred to as the philtrum. Understanding the biological factors behind these patterns explains why certain areas might exhibit less growth.
The Science of Facial Hair Growth
Facial hair, like hair elsewhere on the body, originates from hair follicles. Each follicle undergoes a continuous cycle with three main phases: anagen, catagen, and telogen. The anagen phase is active growth, determining hair length and thickness. This is followed by the catagen (transitional) and telogen (resting) phases, before the hair sheds and the cycle restarts.
Facial hair development is significantly influenced by androgens. Testosterone and its more potent derivative, dihydrotestosterone (DHT, are the primary hormones responsible for stimulating the transformation of vellus (fine, light) hair into terminal (thick, pigmented) hair. These hormones are important for beard and mustache development.
Genetics and Hormonal Sensitivity
Genetics significantly determine facial hair follicle density and responsiveness to androgens. They dictate the number of follicles in specific facial regions from birth. These traits also influence follicle sensitivity to testosterone and DHT.
Different facial areas exhibit varying androgen receptor sensitivity. Even with adequate hormone levels, some follicles respond more robustly to androgen stimulation. These predispositions explain why facial hair patterns differ widely, with some growing full beards and others having sparser growth. Varying hormone sensitivity is a primary reason some facial parts grow hair more readily.
Factors Affecting Growth in the Philtrum
The philtrum, the middle of the mustache area, commonly has a lower density of hair follicles than adjacent upper lip regions. Follicles in this region also have reduced androgen sensitivity. Even with sufficient testosterone and DHT, philtrum follicles may not be effectively stimulated to produce thick, terminal hair.
This is a common, normal variation in facial hair patterns, largely determined by genetics. While genetics are the primary determinant, minor factors can contribute to localized sparse growth. For instance, scarring from childhood injuries or past acne breakouts might affect local hair follicle health. However, these external factors are typically secondary to genetic determination of follicle distribution and sensitivity.
Addressing Concerns About Patchy Growth
Sparse or patchy philtrum hair growth is frequently normal and genetically determined, not a problem. For many, this is simply a natural facial hair variation. Styling can minimize sparser areas, allowing denser hair to cover them.
If sudden, unexplained hair loss or rapid changes occur, consult a healthcare professional. Such changes, especially with other symptoms, could indicate an underlying medical condition. For most, however, philtrum growth patterns are a benign, typical aspect of facial hair development.