Unerarm Hair (also called axillary hair or armpit hair) is the composition of hair in the underarm area. This hair, as most of the other body hair, normally starts to appear at puberty and growth is usually complete by the end of teen age. The release of pheromones from the axilla at this stage of human development suggests association of armpit hair with sexuality. The positive response to olfactory stimulus in mammals and the consequent intensification of the sex drive caused by release of pheromones offers useful clues as to the purpose and importance of axillary hair in humans. It has been suggested that the hair itself acts with a natural "anti-friction" quality between the upper arm and the thorax.