At what age is it advisable to start using deodorant?

Puberty typically begins at around 11 years of age in girls and between 12 and 13 years in boys, although these reference points may vary among individuals.

Puberty marks the gradual transition from a child’s body to that of an adult. This period, which on average lasts five years, is set in motion by a progressive rise in sex hormones, notably androgens in boys and oestrogens in girls. One of the indicators of this transition is the emergence of body odours associated with perspiration. While infants and young children already perspire, their sweat is odourless. This change at puberty is chiefly due to the activation of a new type of sweat gland. Indeed, the human body has two types of sweat glands:

• The eccrine glands, present from birth, produce sweat predominantly composed of water and mineral salts. Their principal function is thermoregulatory, enabling the dissipation of heat to maintain a stable body temperature.

• The apocrine glands, for their part, are found primarily in the armpits, the groin and the chest. They remain inactive during childhood and only become active at puberty under the influence of sex hormones.

Apocrine sweat is thicker and richer in lipids, proteins and organic compounds. This distinctive composition makes it a perfect substrate for bacteria found on the skin’s surface. By feeding on these molecules, these microorganisms produce volatile odorous compounds, notably fatty acids, which are responsible for body odour. This phenomenon is also linked to changes in the skin microbiota during adolescence. Before puberty, the latter is characterised by high bacterial diversity, with a predominance of bacteria of the genus Bacillus. This diversity gradually decreases as the sebaceous glands become more active under the influence of sex hormones. The skin becomes enriched with lipids, which favours the colonisation by lipophilic microorganisms, such as Cutibacterium and the fungus Malassezia.

Furthermore, the emergence of body hair, under the control of sex hormones, particularly androgens, exacerbates bacterial proliferation and unpleasant odours. Indeed, hair, especially in the underarm area, creates a warm, humid and poorly ventilated environment, favourable to the development of micro-organisms. It also retains sweat, prolonging the time it remains in contact with the skin, and therefore increasing the intensity of odours.

In brief, the main factors responsible for the emergence of unpleasant odours are:

• The activation of the apocrine glands by sex hormones, producing a richer sweat.

• The evolution of the cutaneous microbiota and the predominance of lipophilic micro-organisms.

• The appearance of hair, which promotes the proliferation of microorganisms.

Several studies have highlighted the increase in sweating during adolescence. Notably, one study published inMedicine & Science in Sports & Exerciseexamined the sweat gland response to exercise in boys at different stages of pubertal maturity. To this end, three groups of pre-pubertal, mid-pubertal and post-pubertal adolescents were exposed to two consecutive moderate exercise bouts to stimulate sweating. The results show that overall sweat rate increases with pubertal progression, rising from 4.95 mL·min⁻¹·m⁻² in pre-pubertal children to 6.70 mL·min⁻¹·m⁻² in post-pubertal adolescents.

It should be noted that it is not so much the number of active glands that changes—scientists have shown that their density decreases with age—as their individual efficiency. Researchers have observed that, although prepubertal children have a higher density of active sweat glands per cm² (128 ± 8 glands·cm⁻²), each gland produces less sweat (4.6 nL·min⁻¹) than in older adolescents (9.6 nL·min⁻¹). This means that sweating becomes more abundant not because more glands are mobilised, but because each gland produces a greater volume of sweat.

A deodorant can be applied from the onset of the first body odours associated with puberty, typically between 9 and 13 years of age.

There is no medical contraindication to initiating deodorant use at this stage if the need arises. However, it is advisable toselect mild formulations, free from alcohol, particularly for younger, more sensitive skin. The decision on the optimal timing also depends on the child’s own perceptions and needs: a dialogue with them enables this transition to be supported with kindness and respect.

Deodorant, antiperspirant and perspiration suppressant : which to choose for adolescents?

We often confuse these three types of products, yet their actions differ. Deodorants only tackle unpleasant odours: they mask them with fragrance and, when they contain antibacterial agents, they prevent their formation. Antiperspirants both curb odours and reduce the volume of sweat produced for several hours. Finally, prescription-strength antiperspirants are intended for cases of excessive perspiration, known as hyperhidrosis; their effect is more intense and longer-lasting (up to five days), and they are generally recommended by healthcare professionals. There is no specific contraindication to using any of these products during adolescence. However, in the majority of cases, a simple deodorant is sufficient to begin with.

Are there any additional recommendations for minimising body odour?

If the use of a deodorant is appropriate for limiting unpleasant odours, it will not suffice without good hygiene. Taking a daily shower, thoroughly drying the skin (bacteria proliferate in moist regions), possibly removing the hair on one's armpits in cases of excessively bothersome odour, adopting proper dietary hygiene (spicy or fatty foods tend to increase perspiration) and learning to manage stress (strong emotions promote sweating) are all habits that will make all the difference.

• MEYER F. & al. Sweat lactate in exercising children and adolescents of varying physical maturity. Journal of Applied Physiology (1991).

• DUNCAN J. & al. Sweat gland response to exercise in the heat among pre-, mid-, and late-pubertal boys. Medicine & Science in Sports & Exercice (1992).

• BRZEZINSKA-WCISLO L. & al. Dermatological problems of the puberty. Advances in Dermatology (2013).

• HAVENITH G. & al. Body mapping of sweating patterns of pre‑pubertal children during intermittent exercise in a warm environment. European Journal of Applied Physiology (2021).

• KONG H. H. & al. Shifts in the skin bacterial and fungal communities of healthy children transitioning through puberty. Journal of Investigative Dermatology (2022).