Hairs of beard

Hairs of beard refer to the terminal hair that grows on the chin, cheeks, upper lip, jawline, and neck of humans, predominantly in post-pubertal males. It is classified as a secondary sexual characteristic that develops under the influence of androgens, primarily testosterone and its more potent metabolite, dihydrotestosterone (DHT).

Key Characteristics

• Hair type: Beard hairs are terminal hairs — thick, coarse, pigmented, and medullated — as opposed to the fine vellus hairs present before puberty.

• Androgen dependence: The transformation of vellus follicles to terminal follicles in the beard area is driven by androgens acting on the dermal papilla cells. This process typically begins during puberty (Tanner stages III–V) and may continue into the third decade of life.

• Growth cycle: Like all hair, beard hair follows a cyclical pattern of growth phases:

  • Anagen (active growth phase): lasts approximately 2–6 years for beard hair.

  • Catagen (regression phase): a brief transitional period of about 2–3 weeks.

  • Telogen (resting phase): lasts approximately 2–3 months before the hair is shed.

• Growth rate: Beard hair grows at an average rate of approximately 0.27–0.40 mm per day, which is comparable to scalp hair.

• Cross-sectional shape: Beard hairs tend to have an elliptical or irregularly shaped cross-section, which contributes to their characteristic coarse and often curly texture.

• Follicular depth: Beard hair follicles are among the deepest in the body, extending into the subcutaneous fat.

Histological Structure

Each beard hair follicle consists of the standard components:

• Hair shaft (medulla, cortex, and cuticle)

• Inner root sheath

• Outer root sheath

• Dermal papilla — the androgen-responsive mesenchymal structure that regulates follicle cycling and hair growth

• Sebaceous gland — typically well-developed in the beard area, contributing to the oiliness of the skin in this region