Why Do We Have Armpit Hair?

Everyone at some point has wondered why we have armpit hair. While it may seem useless at first glance, it actually plays important bodily functions.
Why Do We Have Armpit Hair?

Written by Ana Núñez

Last update: 25 May, 2022

Why do we have armpit hair? What are its functions?

During puberty, hormonal changes cause hair to grow in the armpits and other body parts.

As people approach adulthood, they notice that those small hairs, which were almost imperceptible to sight, begin to change. This is because they become terminal hair and intervene in certain bodily functions.

Learn more about them below!

The characteristics of terminal hair

Human beings have three types of hair and these change at the different stages of their development. Each has its own characteristics.

Lanugo, which spreads throughout the body, is present from the last trimester of gestation and disappears in the infant’s first months of life. Vellus (non-terminal) hair, is less fine than lanugo, light-colored, and barely noticeable. Terminal hair, which replaces vellus hair, has the following characteristics.

These include the fact that armpit hair is:

  • Highly pigmented and hollow
  • Thick and visible
  • Found mainly in the armpits, the pubic area, the eyebrows, and the eyelashes. The hair that grows on the scalp is also terminal hair.
  • Different from vellus hair because it’s longer. Except for the hair that comes out on the scalp, armpit hair is longer than half an inch but shorter than two inches.

Terminal hair that grows in the armpits, like pubic hair, is also called “ambisexual hair”. This means that it’s present in both males and females. Also, its density will depend on a person’s androgen levels. What’s its specific function?

A woman with underarm hair.
Both the density and other characteristics of body hair are attributed to the activity of androgens in the body.

Why do we have armpit hair?

We have armpit hair due to the action of androgens in the human body. Androgens are a group of hormones, among which testosterone stands out. Regarding the latter, people tend to believe that it’s only present in males. However, this isn’t the case. In fact, it’s also produced in the female reproductive system, although to a lesser extent.

In both sexes, these hormonal changes are responsible for the growth of terminal hair during puberty. Pubic hair appears first. Approximately two years later, armpit hair starts to grow. It grows in each person at a different age, according to their development.

The benefits of underarm or armpit hair

One of the main functions of underarm hair is to regulate body temperature. Hair can protect against cold air or excessive heat that comes into contact with that sensitive area.

Also, it helps retain moisture or slow down sweat production. Thus, it prevents sweat from dripping, as it usually happens in the back.

You should remember that hair alone isn’t responsible for the body odor that can occur in this area. In fact, this odor is due to inadequate hygiene that allows bacteria to build up in the armpits.

1. Armpit hair reduces friction

Armpit hair prevents skin-to-skin contact. Therefore, it reduces the irritation that friction can cause, for example, when you exercise. Not removing this hair considerably reduces the possibility of ingrown hairs, which can cause pain, discomfort, and infections.

You should also read: Discover How to Easily Get Rid of Armpit Hair

2. It releases pheromones

The armpits release chemical messengers that are characteristic of each person, and the presence of hair helps catch them. These messengers are known as pheromones. In particular, they’re chemicals the body naturally produces and releases to act as scent signals, especially in the opposite sex.

The word “pheromone” is a neologism derived from the Greek, which means any chemical substance released by an animal that serves to influence the physiology or behavior of other members of the same species. The definition became popular in the mid-twentieth century. Since then, perfumers began to create fragrances that reproduced the essence of these messengers.

This is why the intensity of underarm odor was associated with an exaltation of masculine virtues. As in animals, these served to increase attractiveness and find a mate.

3. It prevents other discomforts or diseases

Not shaving or waxing your armpit hair reduces the risk of rashes. Similarly, it prevents abscesses that form when clogged pores are exposed to chemicals or dirt. Given this reality, some doctors suggest that it’s best to cut this hair with scissors if you want it to be less noticeable.

A woman with shaved armpits.
Not removing armpit hair helps to avoid irritation in the area. Removing it is a personal decision, associated with aesthetics.

Keep reading to learn more: 5 Natural Remedies that May Help You Get Rid of Ingrown Hairs

Waxing or removing underarm hair is a personal decision

While it’s true that hair removal is a beauty trend, it’s a good idea to know the benefits of not removing your armpit hair. People decide to do so for aesthetic, not medical, reasons. The hair removal beauty trend is characteristic of this century.

Undergoing treatments to keep the skin free of armpit hair is a personal decision. But the choice depends on people’s tastes and customs. Removing or leaving armpit hair are both valid options if you maintain good hygiene habits.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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  • Lanzalaco A, Vanoosthuyze K, Stark C, Swaile D, Rocchetta H, Spruell R. A comparative clinical study of different hair removal procedures and their impact on axillary odor reduction in men. J Cosmet Dermatol. 2016;15(1):58-65. doi:10.1111/jocd.12197
  • Verhaeghe J, Gheysen R, Enzlin P. Pheromones and their effect on women’s mood and sexuality. Facts Views Vis Obgyn. 2013;5(3):189-195.
  • Suro Reyes, José Ángel, Gutiérrez Fernández, Luisa, Ruíz Ávila, Javier y Bouhanna, Pierre. (2007) “El pelo, generalidades y funciones.” Revista Dermatología Cosmética, Médica y Quirúrgica. Volumen 5. N° 4. Octubre-Diciembre.
  • Luo DQ, Liang YH, Li XQ, Zhao YK, Wang F, Sarkar R. Ingrowing Hair: A Case Report. Medicine (Baltimore). 2016;95(19):e3660. doi:10.1097/MD.0000000000003660

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.