Why Do Clothes Smell Even After Washing? The Science of Stubborn Body Odour

You put on a freshly washed T-shirt. It smells clean. Yet an hour later, that familiar underarm odour is back.

You’ve showered, changed your clothes and used your usual deodorant. So where is the smell coming from?

Quite possibly, your T-shirt.

Clothes can hold on to body oils, odour-producing compounds and residues from deodorants or antiperspirants. Washing removes much of this build-up, but some of it can remain trapped in the fibres.

Why Does the Smell Keep Coming Back?

Three things make a difference: the fabric, what has built up in it and how it is washed and dried.

Polyester is particularly good at holding on to oily substances. That helps explain why a sports top can smell unpleasant soon after you put it on, even when it has just come out of the wash.

Damp laundry presents another problem. Leaving wet clothes in the washing machine or drying them in warm, humid conditions can encourage microbial activity and make odours worse.

Over time, repeated wearing and washing can lead to what is sometimes called permastink — a stubborn smell that ordinary laundering struggles to remove.

Some garments become so affected that even repeated treatment fails to make them pleasant to wear again.

What Does the Research Show?

In 2025, a study published in BMC Biology examined synthetic T-shirts worn by 31 people. Although washing removed many odour compounds, the number of bacteria with intact cell membranes increased under the conditions tested. Warm, humid drying also led to stronger odours, with some compounds reappearing after washing.

Researchers at Ghent University had previously compared polyester and cotton T-shirts worn during exercise. In their 2014 study, polyester was rated significantly smellier after 28 hours of storage. The fabrics also carried different bacterial communities.

A 2020 study in Textile Research Journal examined how odour compounds behave through repeated washing. The compounds tested were generally easier to remove from cotton than polyester, where some accumulated over successive cycles.

These findings explain why washing alone does not always solve the problem. What stays in the fabric — and what happens while it dries — matters too.

How to Get Sweat Smell Out of Clothes

If a shirt still smells around the underarms after washing, try treating that area before putting it through another cycle.

1. Pre-treat the underarms. Apply a suitable liquid laundry detergent to the affected fabric, following the product instructions.
2. Try an enzyme detergent. Proteases help break down protein-based residues, while lipases target fats and oils. Check that the detergent is suitable for the fabric.
3. Wash thoroughly. Follow the care label, use the correct detergent dose and avoid overloading the machine.
4. Dry straight away. Good airflow and complete drying matter, particularly with synthetic fabrics.
5. Check before wearing. If the smell remains, repeat the treatment. Adding more fragrance will not necessarily remove the source of the odour.

If a particular polyester top keeps developing the same smell, try wearing cotton for comparison. Cotton is not immune to odours, but it behaves differently in washing.

Do Vinegar and Baking Soda Work?

Enzyme detergents are a sensible starting point for body oils and other organic residues, although no detergent works equally well on every fabric or odour.

White vinegar is a popular laundry remedy, but evidence that it reliably removes stubborn body odour is limited. Regular use may also damage parts of some washing machines.

Baking soda may help with certain smells, though it is not a reliable cure for deeply embedded sweat odour.

For most washable garments, suitable detergent, careful pre-treatment and thorough drying are the better starting points. Never mix vinegar with chlorine bleach.

What Causes Yellow Underarm Stains?

Those yellow marks on a white shirt are not necessarily caused by sweat alone.

Skin oils, sweat components and cosmetic residues can all contribute to deposits in clothing. Antiperspirants commonly contain aluminium salts, while deodorants may contain oils, waxes and other ingredients that can leave marks.

Research published in 2017 examined stubborn underarm stains associated with antiperspirant use and ways of removing them.

Your Skin and Your Clothes Have Different Microbiomes

Bacteria move from your skin onto your clothes throughout the day. Once there, they encounter a different environment, shaped by the fabric and by washing and drying.

This matters because controlling body odour on your skin and removing old smells from clothing are two separate jobs.

Even a deodorant that works well on your skin cannot remove odour molecules already embedded in a T-shirt.

Why This Matters When Using ZINDEO

ZINDEO takes a different approach to body odour. Rather than blocking perspiration or masking smells with added fragrance, it helps control odour where it develops — on the skin.

The less body odour develops on your skin, the less there is to transfer to your clothes.

Unlike aluminium-based antiperspirants, ZINDEO contains no aluminium salts. Anti-odorant Cream is applied sparingly, preferably in the evening. By morning, any visible white residue on the skin will usually have disappeared, reducing the chance of transferring it onto clothing. If white marks do appear on fabric, they can generally be brushed off or washed out easily.

As the ZINDEO RESET routine progresses, application intervals can gradually increase, so you may need to use the cream less frequently.

During the initial RESET period, freshly washed cotton clothing can help you distinguish odour coming from your skin from odour already trapped in an older garment.

For persistent body odour, RESET SET MAX combines SALSOAP® cleansing, Anti-odorant Roll-on and Anti-odorant Cream.

Explore RESET SET MAX →

Sources

1. Díez López et al. (2025). Unravelling the hidden side of laundry: malodour, microbiome and pathogenome. BMC Biology.
2. Callewaert et al. (2014). Microbial odor profile of polyester and cotton clothes after a fitness session. Applied and Environmental Microbiology.
3. Abdul-Bari et al. (2020). Retention and release of odorants in cotton and polyester fabrics following multiple soil/wash procedures. Textile Research Journal.
4. Acikgoz Tufan et al. (2017). A novel washing algorithm for underarm stain removal.