How to Get the Smell Out of a Rashguard
Written by
Combat sports hygiene editorial team
Written and fact-checked by the Combat Sports Hygiene editorial team, drawing on years of hands-on experience training and competing in grappling sports, and reviewed against trusted public-health and dermatology sources.
Published 5 June 2026
Synthetic rashguards are brilliant until they develop that distinctive can't-shift-it stink that seems to survive the wash. I've ruined a few rashguards learning this the hard way, so here's why it happens and how to actually fix it — not just mask it. General guidance, not medical advice, and not about any product we sell.
Why synthetics hold odour
The polyester and elastane that make rashguards stretchy and quick-drying also cling on to body oils and the bacteria that feed on sweat, and ordinary washing doesn't always flush them out. Cotton tends to release odour more easily; technical synthetics trap it, which is the trade-off for kit that wicks and dries fast. Fabric softener makes it worse, not better, by coating the fibres and effectively sealing the smell in.
The routine that works
- Wash promptly. Don't let a damp rashguard fester in a bag — that's where the smell sets in for good. See gym bag hygiene.
- Turn it inside out so the sweaty side faces the water and gets the proper scrub.
- Cold or warm wash, normal detergent dose. Hot water can damage technical fabric; too much detergent leaves residue that traps odour rather than lifting it.
- Skip the fabric softener. A cup of white vinegar in the wash instead helps cut residue and neutralise smell without coating the fibres.
- For stubborn cases, pre-soak in cold water with a scoop of detergent or a dedicated sports wash for an hour before a normal cycle.
- Air dry fully. Don't tumble on high heat, and never put it away even slightly damp — that's how the cycle starts all over again.
What doesn't work (and makes it worse)
A few popular "fixes" backfire. Piling on extra detergent leaves more residue for bacteria to feed on. Fabric softener locks odour in. Spraying deodoriser over a dirty rashguard just layers fragrance on top of the smell, which comes roaring back the moment you sweat. And boiling-hot washes can wreck the fabric's stretch and finish while not necessarily solving anything. If your routine relies on masking rather than removing, the funk keeps winning.
Prevention beats rescue
The honest truth is that it's far easier to keep a rashguard fresh than to resurrect a rank one. Wash after every session, dry it fully, and rotate a couple so none gets re-worn damp — the full routine's in rashguard hygiene. The same logic keeps a gi fresh, even though the fabric's different.
It's not just rashguards
The same synthetic-odour problem applies to anything stretchy and sweat-soaked: spats, compression shorts, grappling socks and synthetic shorts all hold smell the same way, and they all respond to the same routine. Wash them inside out and cool, with a sensible detergent dose and no fabric softener, then dry them fully. If you've rescued a rashguard but your spats still reek, it's almost always because they've been treated as an afterthought — give them the same attention and the problem disappears. The principle is fabric-based, not item-based: technical synthetics trap odour, so technical synthetics all need the same care.
Common questions
Does white vinegar damage the fabric?
Used as directed — a cup in the wash, not neat on the fabric — vinegar is generally gentle on technical kit and rinses out clean. It's a popular trick precisely because it cuts residue and odour without the fibre-coating downside of fabric softener.
Can I use a dedicated sports detergent?
You can; some people find a sports wash helps with stubborn synthetic odour. The fundamentals matter more than the product, though: wash promptly, don't overdose, skip softener, and dry fully. A good routine with normal detergent beats a special product used badly.
It smells the moment I start sweating again — why?
That's the classic sign of trapped residue and bacteria that never fully came out in the wash. A vinegar rinse or a pre-soak, plus easing off the detergent dose, usually breaks the cycle. If it's truly embedded after years of hard use, sometimes a rashguard is simply past its best.
Does baking soda help?
A little added to a wash can help with odour for some people, much like the vinegar trick, by cutting through residue. It's not magic, and it doesn't replace washing promptly, not overdosing detergent and drying fully — but it's a cheap thing to try on a stubborn piece.
Can I just wash it hotter to shift the smell?
Hot water can damage technical fabric's stretch and finish, and it doesn't reliably solve odour that's down to trapped residue anyway. A cool wash done properly — inside out, modest detergent, no softener, full dry — usually beats a hot one, without wrecking the kit.
Can a smell become permanent?
The longer trapped sweat and residue sit in the fabric, the more stubborn they get — a rashguard left funky for months is harder to rescue than one caught early. It's rarely truly permanent, but at some point the easier fix is simply replacing a piece that's had a long, hard life.
This article is general educational information and not medical advice, and it isn't about any Combat Sports Hygiene product. If you have a skin concern, contact a GP or pharmacist.
