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Smelly Shoes: The Insole Is the Problem, Not the Shoe

The upper is rarely the source. Sweat soaks into the insole and the foam beneath it, bacteria feed on it, and because that layer takes more than a day to dry it never gets a chance to recover. Wash the insoles on their own, dry them fully, use baking soda overnight, and alternate two pairs.

Quick fix

  1. Pull the insoles out. If they are the source, you will smell it immediately when you hold one up.
  2. Hand-wash the insoles separately in warm water with a little dish soap or laundry detergent, scrubbing the top surface with a soft brush.
  3. Rinse until the water runs clear, press out the water in a towel, and dry them flat for a full 24 hours away from direct heat.
  4. While they dry, pour two tablespoons of baking soda into each shoe, shake it around, and leave it overnight. Tip it out in the morning.
  5. Rotate two pairs from now on. A shoe worn daily never dries through, and that single habit undoes everything else.

What you need

  • Dish soap or laundry detergent
  • A soft brush — an old toothbrush works for the textured surface
  • Baking soda
  • A clean towel for pressing out water
  • A second pair of shoes to rotate with
  • Rubbing alcohol in a spray bottle, optional

Step by step

  1. 1. Take the insoles out and check them

    Removable insoles absorb most of the sweat a foot produces during a day. Hold one to your nose and compare it to the inside of the shoe. In most cases the insole is clearly stronger, which tells you where to spend your effort. If the insole is glued in, skip to the baking soda and alcohol steps.

  2. 2. Wash the insoles by hand, not in the machine

    Warm water and a small amount of dish soap, worked into the top surface with a soft brush, lifts the sweat residue bacteria feed on. A washing machine soaks the foam core through and can delaminate the layers, so hand-washing with limited water is both gentler and faster to dry.

  3. 3. Rinse thoroughly and press the water out

    Leftover detergent in the foam becomes food for the next round of bacteria, so rinse until no suds appear. Roll the insole in a towel and press firmly rather than wringing it, since twisting breaks the foam down and creates permanent creases.

  4. 4. Dry the insoles flat for a full day

    Lay them flat with air reaching both sides, ideally with a fan nearby. Foam holds water deep inside and can feel dry on the surface while still damp underneath — putting a half-dry insole back in the shoe restarts the problem within hours. Keep them away from radiators, hair dryers, and direct sun, which curl and harden the foam.

  5. 5. Treat the shoe interior while the insoles are out

    Wipe the inside of the shoe with a cloth dampened with rubbing alcohol and let it evaporate, or simply fill the shoe with baking soda overnight. Alcohol evaporates without soaking the lining, which matters because a wet shoe interior is exactly what you are trying to avoid.

  6. 6. Baking soda overnight, then tip it out

    Two tablespoons per shoe, shaken to spread it across the footbed and into the toe. Baking soda absorbs moisture and neutralizes acidic odor compounds. It reduces smell rather than eliminating it, and it works best on a shoe that is already dry — used on a damp shoe it clumps and does very little.

  7. 7. Start rotating two pairs

    A foot releases a meaningful amount of moisture over a day, and a shoe needs roughly 24 hours of air to release it. Wearing the same pair every day means it never reaches dry, so bacteria never get interrupted. Alternating pairs is the single change that keeps the smell from returning.

Safety notes

  • Never mix chlorine bleach with vinegar or any acidic cleaner. The combination releases toxic chlorine gas, and neither belongs in a shoe anyway.
  • Do not machine-dry insoles or shoes on high heat. Foam shrinks, adhesive softens, and soles can separate.
  • Do not put a shoe directly on a radiator or heater. Leather cracks and synthetic uppers deform, and it is a fire risk with prolonged contact.
  • Skip the freezer method. Freezing makes bacteria dormant rather than killing them, and the smell returns as the shoe warms up.
  • Test rubbing alcohol on a hidden spot first. It can lighten dyed linings and damage some glued seams.
  • If a foot itself smells strongly, or the skin between the toes is peeling or itchy, that is a medical matter — treating only the shoes will not resolve it.

Never mix different types of cleaning products. Chlorine bleach combined with acidic cleaners releases toxic gas. Always follow the instructions on the product label.

By situation

Leather dress shoes

Do not wash leather in water. Wipe the interior with a barely damp cloth, use baking soda or a charcoal insert overnight, and put cedar shoe trees in when you take them off. Cedar absorbs moisture and holds the shape, which matters more for leather than for anything else.

Sneakers you can wash fully

Canvas and most synthetic sneakers tolerate a full wash. Take the insoles and laces out first and wash all three separately, then dry everything for a day or two. Skipping the insoles is the reason a freshly washed sneaker sometimes still smells.

Rain boots and non-removable liners

A sealed boot has nowhere for moisture to escape, so it needs forced airflow. Stuff crumpled newspaper in overnight to pull moisture out, replace it once, and consider a low-heat boot dryer rated for footwear rather than an improvised heat source.

The smell is back within a week

Either the insole did not fully dry, or you are still wearing one pair daily. Also consider socks — thin synthetic socks hold sweat against the foot, while cotton or wool moves it away. Changing socks midway through a long day makes a noticeable difference.

Why it happens

  • Sweat itself is nearly odorless. Bacteria on the skin break it down, and their byproducts, mainly isovaleric acid, are what produce the sour smell.
  • Feet release a substantial amount of moisture during a normal day, and most of it ends up in the insole, which is the most absorbent part of the shoe.
  • A damp, warm, enclosed shoe is close to ideal conditions for those bacteria. Without a full drying period the population never drops.
  • Odor compounds bind to the foam and fabric over time. That is why a shoe worn daily for a year keeps some smell even after cleaning, and why replacement insoles are sometimes the practical answer.

Keeping it from coming back

  • Rotate at least two pairs so each gets a full day to dry between wears.
  • Loosen the laces and pull the tongue open when you take shoes off, instead of stacking them in a closed cabinet.
  • Replace insoles once or twice a year. They are inexpensive and they are where the odor accumulates.
  • Wear socks that move moisture — merino wool or a moisture-wicking blend — rather than thin synthetics.
  • Dry shoes fully after rain before putting them away, even if it takes two days.
  • Keep the shoe cabinet ventilated. A closed cabinet with damp shoes inside spreads the smell to everything else in it.

FAQ

Can I put insoles in the washing machine?

It is not recommended. The foam core soaks through, the layers can separate, and the drying time doubles. Hand-washing with a brush cleans the surface where the odor actually is, using far less water.

Does the freezer trick work?

Not durably. Cold makes bacteria dormant rather than killing them, so the smell comes back as the shoe returns to room temperature. Washing and thorough drying address the cause instead.

How long should baking soda sit in a shoe?

Overnight, roughly eight to twelve hours, then tip it out and tap the shoe over a bin. Longer does not add much, and leaving it in permanently means walking on gritty residue.

What about deodorizing sprays?

Most are fragrance layered over the existing smell, which reads as worse rather than better. Sprays with an alcohol base do reduce bacteria somewhat, but they are a supplement to washing and drying, not a replacement.

I have cleaned everything and there is still a faint smell.

Odor compounds bind into aged foam and lining, and at some point cleaning cannot reach them. New insoles usually resolve it for a few dollars. If the shoe is old and the lining is worn through, that is a replacement signal.

Last reviewed: August 25, 2026

Basis & sources:
  • Check the care instructions from your shoe or insole manufacturer before washing, especially for leather and technical footwear.

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