More people are turning to natural deodorants. But do they work, and is there anything wrong with antiperspirants?

We humans have been trying to cover up our odour for millennia. The ancient Egyptians and Greeks were known to douse themselves in perfume. It wasn’t until the late 1880s that the first commercial deodorant as we know it was developed – a US product called Mum, named after “mum’s the word”. Their use became widespread by the 1940s and we’ve been rolling, spraying and smearing the stuff under our arms ever since.

But US YouGov research published in 2019 found that four in 10 Americans aged between 18 and 24 were shunning deodorant, coinciding with a rise in natural alternatives.

There has been an explosion of natural deodorant brands, made with plant and mineral-based ingredients (think, coconut oil and arrowroot). Many of them pledge to allow your armpit to dispel toxins while implying that traditional “chemical-laden” brands contain “nasty ingredients”.

But are typical deodorants actually harmful? Should we be worried about the aluminium that is a key ingredient in antiperspirants? And do natural deodorants work?

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Why do our armpits smell anyway?

We have millions of sweat glands all over our body, and perspiration is actually odourless. But the sweat glands in our armpits and groin – called apocrine glands – are larger and produce a thicker fluid. This sweat is mostly made up of water, with tiny bits of salt, protein and fatty acids mixed in. Once it’s excreted through our pores and comes into contact with the bacteria that thrive in the warm, moist environment under our arms, it produces an aroma you probably know too well.

University of Melbourne professor of dermatology Rod Sinclair, the founder of research centre Sinclair Dermatology, explains that perspiration is an important mechanism: as warm-blooded mammals, we have to maintain a constant core body temperature, and it helps us do this.

“There is a normal distribution in the population in terms of how much people sweat,” Sinclair says. “The average person gets a modicum amount but you also have … light sweaters who are slightly more prone to heatstroke and overheating, and heavy sweaters are more prone to body odour.”

How does deodorant work?

We tend to lump all deodorants in the same category, but there are two distinct types. There’s the basic deodorant, which simply uses strong fragrance to mask body odour. In other words, the sweat, or the wetness, remain.

The more popular type has an antiperspirant component, meaning they can stop glands from sweating altogether. The key ingredient used to do this is an aluminium-based compound.

That’s because the aluminium molecule can block our sweat ducts, Sinclair says. “It causes a build-up behind the blockage which then feeds back onto the gland and tells it to stop manufacturing sweat.”

“It’s well known to switch off the sweat glands temporarily,” says Melbourne-based specialist dermatologist Dr Alice Rudd, spokeswoman for the Australasian College of Dermatologists and founder of clinic Skin Depth Dermatology.

Why does aluminium have such a bad rap?

Most natural deodorants spruik that they are aluminium-free. Rumours have circulated widely for decades – including in a 1990s anonymous chain email – that aluminium causes breast cancer. But experts stress there is no evidence for this.

“It’s completely farcical,” Rudd says.

The most common tall tale is that antiperspirant causes harmful substances to be trapped in our armpit before travelling to the lymph nodes and then the breast. Some natural deodorants manufacturers claim that their product doesn’t inhibit the body’s ability to dispel toxins.

It’s “nice prose”, says Sinclair, but it’s inaccurate because it doesn’t make biological sense. Armpit sweat is not made up of toxins – detoxing our body is the job of organs such as the kidneys and liver, not our sweat glands. Also, while they may appear to be in the same neighbourhood, sweat glands are not connected to lymph nodes.

There are other claims, such as aluminium being absorbed into the skin and triggering changes in oestrogen receptors of breast cells, but researchers have quashed this, not least because the amount of aluminium in antiperspirant is tiny. And even if any is absorbed, this would be minuscule. The American Cancer Society unpicks in detail all the claims related to breast cancer and antiperspirant.

But the rumours have stuck: Professor Bruce Mann, Peter MacCallum Cancer Centre’s director of breast cancer services, still gets asked by his patients whether they should stop using antiperspirant.

“I’ve been in the business since the ’90s, and I’ve been hearing it ever since,” Mann says. “None of the studies have found any link between antiperspirant and breast cancer.”

It’s also been claimed that aluminium can lead to Alzheimer’s disease but no research has been able to prove this.

Dementia Australia’s honorary medical adviser, Associate Professor Michael Woodward, says aluminium is all over our environment, including naturally in food and water, yet there is still no strong correlation between the substance and Alzheimer’s disease, and most elderly people do not get the condition.

“The risk from aluminium, if any, must be small,” Woodward says. “The balance of evidence does not support a specific role for aluminium in Alzheimer’s disease.”

Are the ingredients in natural deodorant better?

The short answer is no, Rudd says, but people like the word “natural”.

“Natural isn’t always better. Dermatologists hate that term because there is no regulation of it,” Rudd says. “Anyone can call anything ‘natural’ and it doesn’t actually mean anything.”

Wearers of natural deodorant still sweat because the products forgo the proven antiperspirant, aluminium. Instead, they use ingredients they say absorbs moisture, such as kaolin clay, and those with antibacterial properties, such as baking soda and coconut oil.

“Whether or not it works is questionable,” Rudd says. “And there’s no real head-to-head clinical studies done against different deodorants.”

Mainly, natural deodorants rely on plant-based, non-synthetic ingredients to create a strong fragrance. Think eucalyptus, bergamot, lavender, sandalwood and more.

“They use lots and lots of smelly stuff to disguise body odour, and then that’s where you can get into wicked problems.”

Rudd commonly sees patients with an allergic reaction to deodorant, and often it’s in people who use a natural one. Fragrance is one of the most common allergens, and “natural” ingredients often have a high allergenic potential. There’s a risk of eczema in the form of contact dermatitis, resulting in a red rash under the arms that can be itchy and sore.

“You definitely see people come in with reactions to natural deodorants, and we would always suggest something dermatologically approved which has no fragrance, no potential irritants,” Rudd says.

Armpit skin is also more easily irritated than other parts of our body because it is thinner, meaning it’s less robust, and it gets a lot of friction from rubbing against our skin and clothing.

Sinclair adds that major consumer healthcare companies conduct extensive testing to find ingredients that are universally effective and tolerated, so problems are more often seen with natural products.

“It’s not necessarily appropriate to assume that just because it’s ‘natural’, it’s going to be less allergenic,” he says.

Do we even need deodorant?

For heavy sweaters, an antiperspirant may be necessary, to keep the armpits dry. About 3 per cent of Australians have hyperhidrosis, a condition characterised by excessive sweating.

“For some people, the sweating is quite debilitating. It can drench T-shirts or coerce them to wear particular colours where you can’t see the sweat,” Rudd says.

Consequences can include boils, bacterial and fungal infections and skin issues, such as hidradenitis.

“[In these scenarios] one of the first things we try to do is turn off the sweat,” Sinclair says. “For people who are getting rashes and boils in their armpit, usually the sweat is a contributing factor.”

(People who sweat uncontrollably should also speak to a doctor because it can indicate an underlying medical problem, such as thyroid issues.)

For most people, however, sweating under our arms isn’t bad for physical health. Generally, people don’t like the smell of body odour, or the feel of sweaty armpits. So, they don’t really need deodorant, except for social reasons, which Sinclair believes shouldn’t be underestimated.

“Antiperspirant has probably made the world a much more liveable place,” Sinclair says.

“It’s now pretty much a standard norm that if you want to actually interact with people, you don’t offend them with body odour. Most people can’t actually smell their own body odour, they get used to it. So, it can be a cause of social ostracisation.”

But at the end of the day, this is personal preference. Rudd has noticed a growing number of people embracing the deodorant-free life.

In fact, she’s one of them.

“I personally don’t wear deodorant. I can’t remember the last time I bought one,” Rudd says.

“I have had Botox [under my arms] on occasion to stop me sweating, but I generally don’t bother.

“It doesn’t bother me and no one has commented on it, so I don’t really feel the need.”

So, what should you choose?

It depends what you’re after. If you’re worried about sweating, then opt for an antiperspirant deodorant that contains aluminium, Rudd says. If you’re only worried about body odour, and you don’t have sensitive skin, then you could try a natural deodorant that’s more fragranced.

“It’s not one size fits all because everybody has a different skin type,” Rudd says. “You don’t need to use deodorant. It’s OK to sweat, and it’s OK to smell, but if you want … to use something fragranced, it’s not like you shouldn’t.”

Rudd’s key message is that a natural deodorant isn’t going to be “better”, nor more effective, than a traditional one. But if you like it, just go for it. If you choose to do this, keep in mind it will probably be a bit of trial and error to find the right one. Some may work better for you than others, and there are countless smells and textures. But there is a benefit that certain smaller “natural” companies have over the traditional corporate giants, and that’s sustainability, with some coming in refillable or compostable packaging.

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