How does deodorant work? Everything you need to know

Everything you need to know about deodorant: How it works, what to avoid, why it fails and can you take it on a plane

Everything you need to know about deodorant: How it works, what to avoid and can you take it on a plane

February 26, 2025

M ost of us (hopefully) are putting on deodorant every day and most of us likely have some specific requirements when it comes to choosing which deodorant to use.

Some of us will prefer sticks, others prefer sprays. Some of us workout a lot so need something to keep us fresh, others sweat simply by being awake so need something more hardcore.

Yet for something we use every day, and which we have such strong opinions on, chances are many of us don’t really understand how deodorant works – or why it sometimes fails. That’s where the science comes in.

In this guide, we explain what deodorant actually does, the differences between deodorant and antiperspirant, what to look for and avoid and how to pick a favourite. Because when you know what’s happening under your arms, you can pick the right product and use it in a way that actually works.

If you’re just looking for the best product, check out our best deodorants for men guide, but if you want to understand why some deodorants are more effective than others, read on.

FURTHER READING: Best body spray for men UK

Deodorant vs antiperspirant: What’s the difference?

Before we get started, we should highlight one major point – although the terms deodorant and antiperspirant are used almost interchangeably, there are key differences.

A product labelled “deodorant” protects against odour, but doesn’t stop you from sweating. A product labelled “antiperspirant” uses a chemical to block sweat which in turn stops the odour.

What’s more, you can use them both, especially if you’re a heavy sweater. Wearing antiperspirant at night and deodorant in the morning has been found to offer the best results.

What does deodorant actually do?

Sweat itself doesn’t smell. After all, it’s just a mix of water, salts and proteins. Instead, body odour is caused when the sweat interacts with the bacteria found living naturally on your skin.

All underarms contain a special type of sweat gland called apocrine glands. These glands don’t become active until puberty and are primarily influenced by hormones, which is why body odour tends to get worse as we get older.

When apocrine sweat is released, it contains molecules such as lipids, amino acids, and proteins which the bacteria use as food. As they “eat” these molecules, the generate what’s known as volatile organic compounds (VOCs) and it’s these which release the body odour smell.

If you want to get deeper in the science, a study published in the Journal of Investigative Dermatology identified two key bacterial strains that are to blame for B.O – Corynebacterium spp. and Staphylococcus hominis. These bacteria metabolise the proteins and fatty acids in sweat into short-chain fatty acids and thioalcohols, which smell particularly strong (and bad).

Other bacteria eating other molecules then create other smells.

Isovaleric acid: This is the cause of sour, sweaty smells and most commonly associated with foot odour.
Butyric acid: This is found in rancid butter but also contributes to the pungent smell of body odour.
3-methyl-2-hexenoic acid: One of the primary molecules linked to armpit odour; this makes your B.O smell musty and stale.
Thioalcohols (sulfur-containing compounds): The strongest contributors to body odour, often described as smelling like onions, garlic, or even rotten eggs.

Some people are genetically predisposed to make more of certain precursors in their sweat, which can lead to stronger smells. For example, a genetic variation in the ABCC11 gene is linked to whether a person produces wet or dry earwax, and this also correlates with the likelihood of having strong underarm odour.

How do men’s deodorants work?

Wild

Whereas antiperspirants typically use a chemical called aluminum zirconium tetrachlorohydrex gly to actively block sweat from the sweat glands. Deodorants tend to be more gentle on the skin. This is because they let sweat through but then neutralise any smell.

They do this in two ways – stopping odour at the source, and masking the smell.

1. Stopping odour at the source

Because body odour is caused by bacteria breaking down sweat, the most effective way to stop this is to stop bacteria from growing. As a result, many deodorants contain antimicrobial agents that kill or slow the reproduction of odour-causing bacteria.

Common antibacterial agents found in deodorants include:

Alcohol (ethanol, isopropyl alcohol): Alcohol kills bacteria which makes your armpit less hospitable for bacterial growth. It’s used a lot in spray deodorants.
Triclosan: This is a synthetic antibacterial agent that disrupts how bacteria cells work. It used to be super popular but is used less often now because of concerns about antimicrobial resistance and environmental impact.
Baking soda (sodium bicarbonate): This works by raising the pH of the skin, making it more difficult for bacteria to thrive. Most bacteria that produce body odour prefer a slightly acidic environment, so increasing alkalinity disrupts their activity.
Magnesium hydroxide: This is found most commonly in natural deodorants. Magnesium compounds work similarly to baking soda by reducing the acidity of your armpits, which helps prevent bacterial growth.

Many people are moving away from aluminium-based antiperspirants because they can be quite harsh on certain people’s skin. They can also impact the environment, and it’s the aluminium salts in such products that leave yellow stains on clothes.

There are brands, including Proverb and Wild, which have found natural alternatives to these salts.

2. Masking the scent

Even with antibacterial ingredients, some smelly compounds can still be produced. To counteract this, deodorants include fragrance compounds that cover up these so-called residual odours. These range from essential oils (tea tree, eucalyptus, lavender, citrus) to synthetic fragrance molecules.

Essential oils have the added benefit of mild antibacterial properties while some synthetic deodorants use cyclodextrins, which act as a “trap”, binding to odour molecules and neutralising them before they reach the air.

Interestingly, fragrance molecules can interact with sweat chemistry. This means some deodorants work differently depending on a person’s body chemistry and explains why a deodorant that smells great on one person might not work as well on you and vice versa.

FURTHER READING: Wild deodorant review: Is the refillable Wild deodorant for men as effective as it claims?

Deodorant vs antiperspirant: Which one do you need?

Choose a deodorant if:

You don’t sweat much but want to control odour
You prefer natural ingredients
You don’t want to block sweat glands

Choose an antiperspirant if:

You sweat heavily and need to stay dry
You need long-lasting protection (24-48 hours)
You want to control both sweat and odour

Some people use both, applying antiperspirant at night (so it has time to work) and deodorant in the morning to freshen up.

How to actually use deodorant

Even the best deodorant won’t work if you use it incorrectly. Here are the most common mistakes and how to fix them.

Applying deodorant to damp skin: Water creates a barrier, making it harder for deodorant to stick to the skin. Always apply deodorant to completely dry underarms after showering.
Using too many swipes: Applying too much product can build up, leading to clogged pores and irritation. Try to stick to 2-3 swipes per armpit.
Expecting natural deodorants to work immediately: If you’re switching from an aluminium-based product, your sweat glands might go into overdrive for a few weeks. Try to stick it out for at least 2-4 weeks for your body to adjust, or try an armpit detox mask to speed up the transition.

What is actually the best deodorant?

Best mens deodorant and natural deodorant for men cheap and luxury

Mbman

The best deodorant ultimately depends on how much you sweat, your body chemistry, lifestyle, preferences and even your genetics. However, as a rule, the most effective deodorants should contain:

A strong antibacterial agent – ethanol, triclosan, or magnesium hydroxide
Odour-neutralising compounds – activated charcoal or baking soda
A pH-balancing ingredient – to reduce bacterial growth

It’s not necessary to have all of these, but it helps to prioritise these ingredients over others. Clinical-strength deodorants often contain higher concentrations of antibacterial agents which is why they tend to work better, but also cost more.

For recommendations of different types – from stick, to spray, natural, vegan and more – visit our best deodorants for men.

How do I stop my armpits from smelling without deodorant?

If you’d rather not use a deodorant, or you’re looking for ways to naturally manage the smell, there are some steps to consider.

Firstly, using an antibacterial soap containing chlorhexidine or benzoyl peroxide has been proven to reduce odour, as has reducing how many sulphur-heavy foods like onions, garlic, and red meat. Adjusting the pH levels of your armpits can help and wearing moisture-wicking fabrics like merino wool or bamboo can help keep underarms dry, reducing bacterial growth.

Will I smell if I stop using deodorant?

Yes, although at least temporarily. Your body gets used to deodorant and over time, bacteria levels can become higher than usual. Especially when you first stop. This leads to a period of stronger smell, often referred to as the “deodorant detox” phase.

However, some research suggests that after just a few weeks, the underarm microbiome becomes more balanced and this leads to odour dropping naturally. If you’re transitioning away from deodorant, you can minimise odour by washing frequently with pH-balanced cleansers and using natural antibacterial alternatives like witch hazel or tea tree oil.

Is it OK to put deodorant on every day?

Daily use of deodorant is generally safe, as long as it doesn’t contain ingredients that irritate your skin. Alcohol-based deodorants can dry out the skin over time, while baking soda-based deodorants can be too alkaline, causing redness. If you have sensitive skin, formulas that are heavy on fragrances can also trigger allergic reactions.

A study in the Journal of the American Academy of Dermatology found that some people develop contact dermatitis from fragrance or preservatives in deodorants. If you experience irritation, switching to a fragrance-free or hypoallergenic formula can help.

Why do my armpits smell even with deodorant?

If you still have B.O despite wearing deodorant, and despite making sure your armpits are clean and alkaline, it could be due to a couple of different things:

Bacteria resistance: Over time, bacteria can adapt to certain antibacterial agents which can stop deodorants working as well.
Incompatible pH balance: If the deodorant’s pH doesn’t match your skin’s natural acidity, it may not prevent odour-causing bacteria from thriving as well as it should, or as well as it promises.
Not using enough product: If you don’t apply enough deodorant, it may not fully coat the underarm area, leaving little pockets of bacteria to form.
Sweating through deodorant: If you sweat excessively, deodorant alone won’t be enough; a combination of deodorant and antiperspirant may be needed. Switching to a stronger antibacterial deodorant or clinical-strength antiperspirant can often help too.

How many swipes of deodorant should I use?

Applying too much or too little deodorant stops it working as well as it should. The ideal amount depends on the formula but there are some general rules:

Stick deodorants: 2-3 swipes per armpit
Roll-ons: Two layers of application
Sprays: Hold 6 inches away and spray for 2-3 seconds

However, be careful not to over-apply because it can cause product to build up, which not only reduces absorption but can cause stains on clothing. You may have seen this if you’ve ever used a spray deodorant and been left with dusty white powder everywhere.

Do you wear deodorant to bed?

If you’re using deodorant alone, there isn’t any benefit to wearing it at night. However, if you’re using an antiperspirant, usually because you sweat a lot, then applying it at night can be more effective. Sweat glands are less active while you sleep, allowing aluminium compounds to fully block the ducts before morning.

Do you put deodorant on after a shower?

Yes, but only when your skin is completely dry. If applied to wet skin, deodorant does not stick as well to the skin, which can make it less effective. Applying antiperspirant, especially, after showering at night allows it to absorb fully before sweating begins the next day.

Which is better, antiperspirant or deodorant?

It depends on whether your concern is smell or sweat:

Deodorants are best for controlling odour, but do not stop sweating.
Antiperspirants are best for reducing sweat production, which in turn helps tackle bad smells.

Should I put deodorant on my feet?

Deodorants can help mask the scent of smelly feet. Some people like to spray it into their shoes to help, too. However, the best way to stop your feet from smelling is to keep them clean and healthy.

Antiperspirants can help reduce the amount of foot sweat and odour, particularly if you’re prone to excessive sweating, known as plantar hyperhidrosis, while clinical studies have shown that topical aluminium chloride hexahydrate (20%) can significantly reduce foot sweat production when applied regularly.

Can you take deodorant on a plane?

If you’re planning to travel soon, you might be wondering if you can take deodorant on the plane. The short answer is yes. The long answer is that it depends on the type of deodorant, and the size of the product.

As a rule, stick deodorants are completely fine to take on a plane. They’re classified as solid toiletries, meaning they don’t fall under the liquids, aerosols, and gels (LAGs) rule enforced by most aviation authorities, including the Civil Aviation Authority (CAA) in the UK and the Transportation Security Administration (TSA) in the US.

And because stick deodorants aren’t liquid, they don’t need to be stored in clear, resealable plastic bags. There are also no restrictions on the size of the product you can bring in your hand luggage. This makes stick deodorants the easiest option for travel.

By contrast, roll-on and spray seodorants are considered liquids or aerosols, which means they’re subject to the 100ml liquid restriction for hand luggage.

Roll-on deodorants are classified as liquids because they contain a fluid solution that is applied to the skin using a rolling applicator.
Spray deodorants fall under aerosol restrictions because they contain pressurised liquid propellants that are released as a fine mist when sprayed.

Airport security regulations limit the amount of liquid passengers can carry in response to concerns about liquid-based explosives, while spray deodorants, like other aerosols, are stored in pressurised containers, which must meet safety guidelines to reduce the risk of accidental discharge or pressure-related hazards on the plane. Because of these restrictions, any roll-on or aerosol deodorant larger than 100ml must be packed in checked luggage rather than carried in a cabin bag.