Your mouthguard is probably the dirtiest piece of gear you own. It sits in your mouth for three to five sessions a week, absorbs saliva, sometimes blood, picks up bacteria from sparring, and then gets sealed in a plastic case still damp. Two weeks in and it smells like something died in there.
Why Fighters Need to Clean Mouthguards Differently
Most cleaning guides are written by dentists for nightguard users. That's a different scenario. Nightguard users put a clean guard in a clean mouth for eight hours of quiet sleep. You're wearing yours through hard training, possibly with blood from a cut lip, and packing it away while it's still wet.
Boil-and-bite guards (the $15-25 ones most fighters use daily) are made of EVA thermoplastic with microscopic texture. Bacteria settle into those grooves and thrive in a damp, closed case. You need three levels of cleaning: immediate, daily, and weekly deep clean.
The Routine That Actually Works
Immediate (right when training ends)
The single most important step. Rinse the guard under cold water the second you take it out. Not later, not when you get home, right then. Cold water only. Hot water can warp the thermoplastic and ruin the fit. Most bacteria colonization happens in the first hour after training while the guard is warm and wet. A 10-second rinse prevents most of the problem.
Daily (after each session, at home)
Brush the guard with a soft-bristle toothbrush (dedicated, not your regular one) and mild soap. Not toothpaste. Most toothpastes contain abrasives that scratch the surface, and those scratches are where bacteria hide. Mild hand soap or dish soap works. Brush all surfaces including the grooves. Rinse completely. Let it air dry on a clean towel before capping the case.
Weekly (deep clean)
For fighters training 3-5x a week, once a week is the minimum. Pick one:
- Denture cleaning tablet - Drop one in lukewarm water, soak the guard 15-20 minutes. The effervescent formula is designed for this kind of plastic.
- Hydrogen peroxide soak - Equal parts 3% hydrogen peroxide and water. Soak 10 minutes. Disinfects and helps with staining.
- White vinegar soak - 1 part white vinegar to 3 parts water. Soak 20-30 minutes. Breaks down protein buildup.
Rinse thoroughly after any soak. Never soak in undiluted alcohol-based mouthwash. Alcohol dries out the thermoplastic and makes it brittle.
If Your Mouthguard Already Stinks
- Brush thoroughly with soap and water
- Soak in 1:3 white vinegar and water for 30 minutes
- Rinse completely
- Soak in equal parts 3% hydrogen peroxide and water for 10 minutes
- Rinse and air dry
The vinegar breaks down protein buildup. The peroxide kills what's left. If that doesn't fix it, the guard is past saving.
What's the Black Stuff?
Black spots inside the guard are mold. Once it's visible, soaking won't reliably kill the whole colony. Get a new guard. Don't wear a moldy one, not even one more session.
Don't Forget the Case
If you clean your guard and put it into a case that hasn't been washed in months, you're re-contaminating it every time. Wash the case in soapy water once a week and leave it open between sessions to dry. A closed damp case is the same problem as a closed damp guard.
Same principle applies to your gym bag. Empty it when you get home and let everything air out. We wrote a full post on storing boxing gear so it doesn't smell that covers the bag side of this.
At the Gym With No Soap or Case
- Rinse with cold water at the sink. Minimum.
- Rinse with diluted alcohol-free mouthwash if you have it.
- Wrap in a clean paper towel to air dry rather than sealing it wet in a plastic bag.
Don't share a guard. Don't keep using it for a second session if the first involved blood or heavy sparring. Go home, clean it properly, or use a backup.
When to Replace
A boil-and-bite guard used 3-5x a week lasts around 3 to 6 months. Replace it when:
- The fit has loosened and it shifts while you train
- Visible tears, cracks, or permanent bite-through marks
- Black discoloration that doesn't come out with cleaning
- Persistent smell that survives a proper deep clean
- The material has become cloudy or chalky
Custom-fit guards from a dentist last 1-2 years of frequent use but need the same routine.
What Not to Do
Don't put it in the dishwasher. The heat warps the thermoplastic and destroys the fit.
Don't boil it to sterilize. Hot enough to kill bacteria is hot enough to ruin the shape.
Don't use regular toothpaste. The abrasives scratch the surface, creating more places for bacteria to hide.
Don't use bleach. Degrades the material and leaves residue that's not safe to put in your mouth.
Don't store it wet in a sealed case. Single biggest contributor to mouthguard smell.
Don't share a mouthguard. Ever.
FAQ
Why does my mouthguard smell even after I clean it?
Usually one of three things: you're storing it wet, you haven't deep cleaned it in a while, or bacteria have colonized micro-scratches that regular brushing can't reach. Try the vinegar then hydrogen peroxide soak. If that doesn't fix it, replace it.
Can I use hydrogen peroxide to clean a mouthguard?
Yes. 3% hydrogen peroxide diluted 1:1 with water for 10 minutes is one of the best deep clean options. Rinse thoroughly after. Don't use stronger concentrations.
Shane McCarthy is the co-founder of Drago Boxing. He has been boxing for 6 years, holds a Canadian national title, and has patents on two boxing products.