How to wash workout clothes that smell (even after washing)

You wash your workout shirt. It comes out smelling clean. You put it on for your next gym session and within 5 minutes — that smell is back. You’re not going crazy. The bacteria causing the smell weren’t actually killed in the wash, just briefly suppressed by detergent.

Here’s why this happens to synthetic workout fabrics specifically, and the routine that actually fixes it.

Why polyester holds smell when cotton doesn’t

Workout clothes are mostly polyester, nylon, and spandex. Those fabrics are designed to wick moisture away from your skin — but they have an unintended side effect: their fibers also hold onto skin bacteria much more tightly than cotton does.

Regular detergent + cold water will get the visible dirt out, but it can’t penetrate deep enough into synthetic fibers to kill the bacteria. As soon as your body warms the shirt back up, the bacteria reactivate and start producing the smell.

Cotton doesn’t have this problem because its fibers are more porous and water washes through them.

The fix: a 3-step routine

Do this once on every “smelly” item, then a maintenance version each subsequent wash.

Step 1: Pre-soak in vinegar (one-time deep clean)

Fill a sink, tub, or bucket with cold water + 1 cup of distilled white vinegar per gallon. Submerge the smelly clothes and let them soak for 30–60 minutes.

The vinegar dissolves the bacterial biofilm clinging to the synthetic fibers. You’re not washing the clothes yet — just dissolving the source of the smell.

Step 2: Wash with proper detergent

Squeeze out the vinegar water and put the clothes in the washer. Add the normal amount of detergent. Some brands make “sport” or “active wear” detergent (Tide Sport, Win Sports Detergent, HEX Performance). They’re not strictly necessary but they do work better on synthetics.

Wash on cold water, normal cycle. Do NOT add fabric softener — it coats the fibers and makes the smell come back faster.

Step 3: Air dry if possible

Air drying is best for synthetics. The high heat of the dryer can bake any remaining bacteria deeper into the fibers. If you must use a dryer, use low heat and pull the clothes out as soon as they’re dry.

That’s the deep clean. Now for maintenance.

Maintenance routine (every wash going forward)

Once you’ve done the deep clean once, here’s the routine for ongoing washes:

1. Don’t let sweaty workout clothes sit in a gym bag overnight. Hang them up or rinse them as soon as you get home. Bacteria multiply fast in damp fabric.
2. Wash inside out. Most of the bacteria are on the inside surface. Inside-out exposes them directly to the water and detergent.
3. Add 1/4 cup of vinegar to the washer in addition to detergent (it goes in the fabric softener dispenser slot). This stops smell from re-establishing.
4. Wash separately from cotton when possible. Cotton sheds lint that sticks to synthetics and traps smell.
5. Cold water, no fabric softener, low or no dryer heat.

What if it still smells?

A few troubleshooting steps:

It’s worse on certain items only: Those items probably have a buildup of antibacterial deodorant or sunscreen. Soak just those items in vinegar twice in a row.

Your washer smells: Modern front-loaders develop mildew in the door seal. Run an empty cycle with bleach or washer-cleaner tablets once a month to keep it fresh. A smelly washer makes everything in it smell.

It’s mostly your shirts under the arms: Try a baking soda paste rubbed into the underarm area before each wash. Let it sit 10 minutes, then wash normally. This neutralizes the protein in sweat that bacteria feed on.

Brand-new athletic wear smells immediately: Some new athletic clothes ship with antibacterial coatings that interact badly with deodorant. Wash them once with vinegar before first wearing.

Things that don’t actually help

Skip these — they’re commonly recommended but don’t really work:

• Hot water washes. Polyester can’t take much heat, and hot water often sets the smell rather than removes it.
• Bleach. Yellows synthetic fibers and damages spandex. Don’t use it on workout clothes.
• Doubling the detergent. Makes the smell worse over time (more residue = more food for bacteria).
• Fabric softener “fresh scent” sprays. They mask the smell briefly but feed the bacteria.

Final tip: rotate your shirts

Even with perfect washing, the same shirt worn for 3 sessions in a row will gradually accumulate smell faster than one worn weekly. Rotate through 4–5 shirts instead of always grabbing your favorite.

→ How much detergent to actually use → Why your towels are scratchy