Type "shoe odour absorber" into Google and you'll get a wall of options. Charcoal bags. Odour eaters. A spoonful of baking soda. Someone's nan swearing by a bowl of cat litter. Some of it works. Some of it is just a placebo you shake into your trainers.
I've spent years selling the expensive end of this market, so I've got no reason to talk up a £3 bag of charcoal. Here's the straight version of what each one does, where it falls short, and when it's genuinely all you need.
What an odour absorber actually does
An absorber pulls moisture and odour molecules out of the air trapped inside your shoe and holds onto them. That's a different job to a spray or a deodoriser, which adds a scent or works on the surface rather than removing anything.
Absorbing sounds like the answer, and for the right shoe it genuinely helps. The catch is what it can't reach. An absorber only deals with what's floating around inside the shoe. It doesn't touch the moisture soaked into the foam of the midsole, it doesn't get into the lining, and it does nothing about the bacteria and fungi that keep producing the smell in the first place.
Think of a full washing-up bowl under a tap that's still running. The bowl does its job. The tap doesn't stop.
The options, one by one
Charcoal bags for shoes
The strongest option on this list. Activated charcoal has a huge internal surface area, so it pulls in both moisture and odour rather than just one or the other. You get it as small bags you drop into a shoe overnight.
| Absorbs odour | Yes, effectively |
| Absorbs moisture | Yes |
| Reusable | Yes, leave it in sunlight for a few hours to refresh it |
| Rough price | Around £8-15 for a set |
| Best for | Shoes worn occasionally, wardrobes, gym bags |
It won't do anything about the bacteria living in the material, so the smell keeps getting produced even if the bag is doing its job well.
Odour eaters and zeolite bags
Sold under all sorts of brand names, but most "odour eaters" for shoes are either activated charcoal or zeolite, a porous mineral that works on the same principle. Zeolite is just as reusable and performs about the same as charcoal.
Worth knowing: some odour eater insoles work differently. Those sit under your foot and manage moisture as you walk, rather than sitting in an empty shoe overnight. Handy as prevention, not as a fix for a shoe that's already smelling.
Baking soda in shoes
The classic kitchen-cupboard trick. Sodium bicarbonate absorbs some moisture and neutralises acidic odours reasonably well.
- Cheap and you probably already have it in the house
- Takes the edge off moisture
- Leaves powder residue that clumps and ends up on your socks
- Doesn't touch odours that aren't acidic
- Shows up as white marks on dark fabric
If you do use it, tip it in at night and tap the shoe out thoroughly the next morning. Don't leave it sitting for days.
Rice
Rice absorbs moisture, that part is true. It's slow about it though, and it mostly pulls moisture from the air inside the shoe rather than out of the sole itself.
Barely worth the effort in a shoe. Save it for a wet phone, and even there it's overrated.
Cat litter
Sounds odd, works better than you'd expect. Most cat litter is zeolite or silica gel, both decent absorbers. Tip some into an old sock and knot the end.
Functional and cheap. A bit bulky in your trainer, and make sure you grab an unscented variety rather than one with added fragrance.
Cedar blocks and shoe trees
Cedar wood pulls out a little moisture and gives off its own scent, which is mostly masking rather than fixing anything.
Nice for smart shoes sitting in a wardrobe. Not enough for anything you actually train or run in.
The freezer trick
Shoes in a bag, a night in the freezer, bacteria dead by morning. That's the story that does the rounds.
It doesn't hold up. Cold slows bacteria right down, but most species survive it fine and get going again once the shoe warms back up to room temperature. The cold can also be rough on glued seams, and any odour already baked into the material stays put.
Skip it. Your freezer ends up smelling of trainer and the trainer smells of trainer again within a day.
Talc and foot powder
Powder keeps your foot drier, which slows down how fast odour builds up. That's useful, but it's prevention at the foot, not a cure for a shoe that's already holding moisture. Powder residue can also clump over time.
Fine as a habit alongside something else. Not a fix on its own.
What none of these can do
Notice the pattern. Every option above absorbs something. None of them gets to the root of it.
The root is this: a foot can shed roughly a small cupful of moisture a day, that moisture soaks into the insole and the midsole foam, and bacteria feed on it there. A charcoal bag sitting in the opening of the shoe never reaches that far in. It only catches the air drifting past it.
That's why the smell always creeps back in trainers and daily shoes. It's not that you picked the wrong absorber. It's that the shoe itself never actually dries out.
When is an odour absorber enough?
I'm not going to tell you every shoe needs a machine. For these, a decent absorber does the job fine:
- Smart shoes you wear a handful of times a month
- Shoes sitting in a wardrobe that pick up a musty smell
- A gym bag, so the rest of your kit doesn't take on the odour
- Boots you only wear a few weeks a year
And for these, it won't cut it:
- Trainers coming back damp two or three times a week from training
- Work boots worn eight hours a day
- Shoes where the smell is back within a day of treating them
- Shoes still damp the morning after a downpour
The next step, if an absorber isn't cutting it
If you're in that second group, only one order of operations actually works: get the moisture out first, then tackle the bacteria and fungi already living in the material.
That's what a shoe dryer built with active oxygen does. Warm air pulls the moisture out of the sole and lining, and the active oxygen reaches everywhere the air can go, including seams and foam no bag or spray can get near. It doesn't kill anything and we won't claim it does, but it does tackle the bacteria and fungi that keep producing the odour, on top of doing the drying job properly.
If budget is tight, the ShoeDry Airo (around €50) is a fair starting point. It uses ION rather than active oxygen, so it's gentler on stubborn smells, and it skips the extra programmes, heel dryer and automatic start you get on the higher-end machines.
For a shoe built specifically to dry and treat trainers in one go, our Shoefresh Opod White (€129) runs a full programme with active oxygen, and the Opod Detect (€179) adds moisture sensors that decide for themselves whether your shoes need another round. For boots, ski boots or gloves, the Opod Mini, including adapter, comes in at €79.
Want a scent on top once your shoes are actually dry? The Shoefresh Perfume 2-pack (€24.95) is a nice finishing touch, though it's not a substitute for drying the shoe out properly.
Curious how the whole approach compares to a basic dryer? Our complete guide to shoe dryers covers how the drying and cleaning sides work, and our shoe deodorizer guide lines up sprays, sachets and machines side by side.
FAQ
What is a shoe odour absorber?
Anything that pulls moisture and odour molecules out of the air inside a shoe and holds onto them, rather than adding a scent on top. Charcoal bags, odour eaters, baking soda and cat litter all fall into this category.
Do charcoal bags for shoes actually work?
Yes, better than most alternatives on this list. They absorb both moisture and odour and can be reused if you let them dry out in sunlight now and then. They won't do anything about the bacteria causing the smell to keep coming back.
Is baking soda safe to put in trainers?
It's safe, but it's messy. Expect powder residue and white marks on dark fabric. Tip it in overnight and tap it out thoroughly the next morning rather than leaving it in for days.
How long does a shoe odour absorber last?
Charcoal and zeolite bags keep working for a good while as long as you air them out in sunlight regularly so the moisture they've picked up can evaporate. Once saturated and left damp, they stop doing much.
Can I use rice as a moisture absorber for shoes?
You can, but it's slow and barely makes a dent inside a shoe. It's better known for phones than footwear, and even that reputation is a bit overrated.
Do odour absorbers tackle bacteria and fungi?
No. They absorb moisture and odour molecules floating in the shoe, but they don't tackle the bacteria and fungi living in the material itself. For that you need proper drying, ideally with active oxygen.
Odour absorber or a proper dryer, which do I actually need?
If your shoes are only lightly used or sit in storage, an absorber is a sensible, cheap option. If they come back damp regularly or the smell returns within a day, only drying the shoe out properly and tackling what's living in it will actually solve it. Our best shoe dryers of 2026 lines up the options if you're at that point.