Science of Sweating (and Why We Think Kids Should Keep Doing It)
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Time to read 3 min
Parents usually meet body odor the way we meet sudden growth spurts: unexpectedly, somewhere between the classroom and the walk home from school.
That faint, unfamiliar scent isn’t a problem to erase. It’s the body announcing that change has begun.
If that’s you right now, hello. Here’s a calm, science-true look at what’s happening, what helps, and how to keep kids feeling fresh without stopping what’s natural.
What happens when kids start to sweat
Sweating is the body’s built-in cooling system.
When internal temperature rises either from heat, activity, stress, or even excitement, the brain signals sweat glands to release fluid onto the skin. As that fluid evaporates, it draws heat away and lowers overall body temperature. This process is called evaporative cooling, and it’s essential for keeping organs safe, especially in children who tend to heat up more quickly than adults.
Young children rely primarily on eccrine sweat glands, which are found all over the body. These glands produce a light, watery sweat made mostly of water, salt, and trace minerals. It’s extremely effective for cooling but almost impossible to smell because it contains very little organic material for bacteria to break down.
As children grows older, hormonal shifts activate a second type of sweat gland called the apocrine glands, concentrated in the underarms and groin.
Unlike eccrine sweat, apocrine sweat is thicker and contains proteins and lipids, the components that bacteria on the skin can metabolise. This richer composition doesn’t affect cooling, but it does create the conditions for odor to develop later.
This is why sweat can suddenly feel “heavier” or “different” in older kids. The chemistry of the sweat itself has changed even if their habits haven’t.
How sweat becomes a smell
Fresh sweat, even apocrine sweat, doesn’t smell. Odor appears only when certain bacteria on the skin begin to break down the proteins and lipids in apocrine sweat.
Under the arms, this process is driven by specific bacterias such as Corynebacterium, which convert sweat components into small, volatile molecules - the things parents recognise as body odor. These molecules include acids and sulfur-containing compounds that easily evaporate, which is why they reach the nose so quickly.
When they are younger, kids sweat plenty but they don’t smell because they mostly produce eccrine sweat, which bacteria can’t easily metabolise. Once apocrine glands switch on, sweat becomes richer, the microbiome becomes more active, and scent appears almost overnight.
It’s not poor hygiene. It’s biology. And it’s normal.
Sweat is supposed to happen
Sweating is essential for:
cooling the body
protecting internal organs
supporting the skin microbiome
maintaining a healthy moisture barrier
Blocking sweat interferes with these natural functions.
Antiperspirants do this by plugging sweat ducts with aluminum salts, reducing the body’s ability to release heat.
For children whose temperature regulation systems are still developing, this isn’t ideal.
Deodorants, on the other hand, work with the body by managing odor rather than stopping sweat. They help keep bacteria in check without interfering with the body’s natural cooling system.
So the goal isn’t to stop sweat. It’s to let kids move, play, and grow comfortably while their bodies learn their new rhythm.
How to know when to start deodorant
When daily cleansing is no longer enough to manage odor, it’s usually time.
For most families, this happens around eight to ten years old or can even start at ages 6, when apocrine glands fully activate and the microbiome becomes more active.
The goal here isn’t to mask the scent or to stop them from sweating entirely.
It’s simply to help kids feel fresh and comfortable during a natural stage of development.
What to look for in a kids’ deodorant
Choose deodorant, not antiperspirant. Let sweat flow naturally.
Gentle, non-occlusive textures. Choose formulas that feel soft on the skin, absorb cleanly, and let the underarms breathe throughout the day.
Alcohol- and aluminum-free formulas. Kinder on young, reactive skin.
Dermatologically tested for sensitive skin. Children’s underarms are thinner and more delicate.
Nautrally scented or fragrance-free options. Strong perfume or baking soda can irritate.
A Simple, Fresh Routine for Growing Kids
A good routine is often all it takes to keep kids feeling fresh during this stage of change.
A daily cleanse with a gentle product like Sensibulle Shower Jelly, followed by a thorough dry, helps rebalance the underarms after heat or play. Light, breathable fabrics such as cotton or bamboo reduce the warmth and moisture that odor-causing bacteria love, and changing into a fresh top after sports can make an outsized difference in keeping scent at bay.
From there, the right products can support the routine without interrupting what the body is designed to do. A soft towel-dry after bathing and a mild deodorant like TOOFRUIT Mon Premier Déo create a simple, confidence-building sequence — one that manages odor gently while allowing their bodies to sweat naturally and healthily.
