Quick Answer: To remove urine from a memory foam mattress, blot the area immediately with towels, then apply a solution of equal parts white vinegar and water. After the vinegar dries, cover the area with baking soda for 8 to 10 hours to neutralize odour, then vacuum thoroughly. For set-in stains, an enzyme-based cleaner designed for pet or biological stains works best. Never soak memory foam or use a steam cleaner on it.
In This Guide
Reading Time: 7 minutes
Act Fast: Cleaning Fresh Urine
Speed matters. Memory foam is absorbent, and urine soaks deeper into the open-cell structure the longer it sits. If you catch the accident within minutes, you have the best chance of preventing a permanent stain and lingering odour.
Step 1: Strip the Bedding Immediately
Remove all sheets, mattress pads, and protectors. Put them directly into the washing machine on a cold water cycle. Hot water can set urine proteins into fabric, making stains harder to remove.
Step 2: Blot, Do Not Rub
Press clean, dry towels firmly onto the wet area to absorb as much urine as possible. Use a pressing and lifting motion. Rubbing pushes the urine deeper into the foam. Continue with fresh towels until minimal moisture transfers to the towel.
Step 3: Apply Vinegar Solution
Mix equal parts white vinegar and cool water in a spray bottle. Spray the affected area generously but do not saturate the foam. The vinegar neutralizes the ammonia in urine and begins breaking down the uric acid crystals that cause lingering odour. Let the solution sit for 10 to 15 minutes.
Step 4: Blot Again
Press clean towels into the area to absorb the vinegar solution along with dissolved urine compounds. Repeat the blotting until the towels come away mostly dry.
Step 5: Apply Baking Soda
Spread a generous layer of baking soda over the entire affected area. The baking soda absorbs remaining moisture and neutralizes odour as it dries. Leave it for 8 to 10 hours, ideally overnight. Open a window or run a fan to improve air circulation and speed drying.
Step 6: Vacuum Thoroughly
Vacuum up all the baking soda using the upholstery attachment on your vacuum cleaner. Go over the area multiple times to remove all residue from the foam's surface texture. Check that the area is completely dry before replacing bedding.
Drying Tip
Memory foam must be completely dry before you put sheets back on. Trapped moisture leads to mould growth inside the foam, which is far worse than a urine stain. If possible, stand the mattress on its side near an open window or place a fan blowing directly on the cleaned area. In Ontario's winter months, a dehumidifier in the room speeds drying when opening windows is not practical.
Cleaning Dried Urine Stains
Dried urine is harder to remove because uric acid crystals have bonded to the foam. Standard cleaning solutions may remove the visible stain but leave the odour-causing crystals intact. Enzyme cleaners are the answer.
Enzyme Cleaner Method
Enzyme-based cleaners contain biological agents that break down uric acid at a molecular level. These are the same cleaners used for pet accidents and are available at most grocery and pet supply stores in Brantford.
Enzyme Cleaning Steps
- Choose the right product: Look for an enzyme cleaner specifically labelled for urine, pet stains, or biological stains. Common brands include Nature's Miracle, Rocco and Roxie, and Bio-Enz
- Apply generously: Spray or pour the enzyme cleaner onto the stained area. The enzymes need to reach the same depth as the urine penetrated
- Cover with plastic wrap: Place plastic wrap over the treated area to prevent the cleaner from evaporating before the enzymes finish working. Enzymes need moisture to function
- Wait 24 hours: Enzyme cleaners work slowly. Do not disturb the area for at least 24 hours
- Remove plastic and blot: Remove the plastic wrap, blot with clean towels, and allow the area to air dry completely
- Apply baking soda: After the enzyme cleaner has dried, apply baking soda for an additional 8 hours to absorb any remaining moisture and odour
Hydrogen Peroxide Method (For Stubborn Stains)
If the enzyme cleaner does not fully remove a visible stain, a mild hydrogen peroxide solution can help. Mix 240 ml (1 cup) of 3% hydrogen peroxide with 45 ml (3 tablespoons) of baking soda and a small drop of dish soap. Spray lightly onto the stain without saturating the foam. Let it dry completely. Note that hydrogen peroxide may slightly lighten the foam colour, but since the foam is under your sheets, this is rarely a concern.
Why Urine Odour Persists
Urine contains urea, which bacteria break down into ammonia (the sharp smell you notice immediately). But the lasting odour comes from uric acid crystals, which are not water-soluble and resist standard cleaning. These crystals reactivate when exposed to moisture or humidity, which is why a "cleaned" mattress can smell again on humid days. Enzyme cleaners are the only household solution that fully decomposes uric acid crystals, which is why they are recommended for permanent odour removal.
Removing Urine Odour
Even after the stain is gone, odour can linger in memory foam because the open-cell structure traps uric acid crystals deep inside. Here are additional odour-fighting strategies.
Baking Soda Deep Treatment
For persistent odour, apply a thick layer of baking soda (5 to 8 mm deep) over the entire affected area. Add 5 to 10 drops of essential oil (lavender or tea tree work well) to the baking soda before spreading for additional odour masking. Leave for 24 hours, then vacuum. Repeat if necessary.
Ventilation
Stand the mattress on its side in a well-ventilated room for 24 to 48 hours after cleaning. Fresh air circulation helps dissipate trapped odours from within the foam structure. If weather permits, placing the mattress in indirect sunlight (not direct sun, which degrades foam) for a few hours accelerates odour removal.
Activated Charcoal
Place activated charcoal bags or bowls of activated charcoal near the mattress for several days. Charcoal is a powerful odour absorber that works passively, drawing ammonia and other volatile compounds out of the air and foam surface.
What Not to Do with Memory Foam
Memory foam requires different care than traditional innerspring mattresses. Several common cleaning approaches that work on other surfaces can damage memory foam permanently.
Avoid These Mistakes
- Do not soak the foam: Memory foam absorbs water like a sponge and takes days to dry. Excessive moisture leads to mould growth deep inside the foam where you cannot see or reach it
- Do not use a steam cleaner: The heat and moisture combination damages the foam's cell structure and can cause it to break down prematurely
- Do not use bleach: Bleach damages polyurethane foam, causing it to deteriorate and crumble. It also creates toxic fumes when combined with ammonia in urine
- Do not put the mattress in a washing machine: This seems obvious, but memory foam toppers sometimes get tossed in. The agitation destroys the foam structure
- Do not use a hair dryer on high heat: Concentrated heat damages memory foam. If using a hair dryer to speed drying, use the cool setting only
- Do not flip the mattress to hide the stain: The urine and odour are still there, and the moisture may cause mould growth if the stain is trapped against the bed frame
Preventing Future Accidents
The best approach to urine on a memory foam mattress is preventing it from reaching the foam in the first place. A waterproof mattress protector is the single most effective investment for mattress longevity.
Waterproof Mattress Protectors
Modern waterproof protectors are nothing like the crinkly plastic covers of the past. Quality protectors use a thin polyurethane membrane backed by soft fabric that feels like a regular fitted sheet. They block all liquids from reaching the mattress while remaining breathable enough to sleep on comfortably.
Dorothy, our sleep specialist, recommends protectors for every mattress we sell. "A good protector costs a fraction of a new mattress," she says. "It protects against accidents, spills, sweat, and dust mites. If an accident happens, you wash the protector instead of spending hours cleaning foam. It also keeps your warranty valid, since most warranties are voided by stains."
When to Consider Replacement
If urine has soaked deeply into a memory foam mattress multiple times, or if mould has developed from moisture trapped inside the foam, cleaning may not be enough. Signs that your mattress may need replacing include persistent odour despite thorough cleaning, visible mould spots, foam that has become soft or crumbly in the affected area, or allergic reactions when sleeping on the mattress.
Mattress Replacement in Brantford
If your mattress is beyond saving, visit us at 441 1/2 West Street in Brantford. We carry a range of quality mattresses starting with our Restonic ComfortCare Queen at $1,619 with 1,222 individually wrapped coils. We also carry mattress protectors to keep your new mattress clean from day one. We offer old mattress removal with delivery, so you do not have to worry about disposing of the old one yourself.
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441 1/2 West Street, Brantford, Ontario
Call 519-770-0001Frequently Asked Questions
Can you fully remove urine from a memory foam mattress?
Fresh urine can usually be fully removed with prompt cleaning using the vinegar and baking soda method. Dried urine requires an enzyme-based cleaner to break down uric acid crystals that cause lingering odour. Deep, repeated soaking may leave some residual odour that is difficult to completely eliminate.
Does vinegar remove urine smell from a mattress?
White vinegar neutralizes the ammonia component of urine odour and is effective for fresh accidents. However, vinegar alone does not break down uric acid crystals, which cause odour to return in humid conditions. For complete odour removal, follow vinegar treatment with baking soda and consider an enzyme cleaner for stubborn smells.
How long does it take for a memory foam mattress to dry after cleaning?
Memory foam takes 24 to 48 hours to dry completely after cleaning, depending on how much liquid was used and room ventilation. In Ontario's humid summer months, drying may take longer. Use fans, open windows, and a dehumidifier to speed the process. Never put bedding back on until the foam is completely dry.
Will cleaning urine void my mattress warranty?
The cleaning itself does not void the warranty, but stains on the mattress can. Most mattress warranties state that visible stains void coverage. This is why a waterproof mattress protector is so important. If your mattress already has a stain, clean it as well as possible, but be aware the warranty may already be affected.
Does Mattress Miracle sell waterproof mattress protectors?
Yes, we carry waterproof mattress protectors that block all liquids while remaining breathable and comfortable. A protector is the best investment for keeping your mattress clean and your warranty valid. Visit us at 441 1/2 West Street in Brantford or call (519) 770-0001.
Sources
- Boor, B.E., et al. (2014). Characterization of particle resuspension from mattresses. Indoor Air, 24(6), 592-603.
- Arundel, A.V., et al. (1986). Indirect health effects of relative humidity in indoor environments. Environmental Health Perspectives, 65, 351-361.
- Okamoto-Mizuno, K., & Mizuno, K. (2012). Effects of thermal environment on sleep and circadian rhythm. Journal of Physiological Anthropology, 31(1), 14. doi.org/10.1186/1880-6805-31-14
- Health Canada. (2024). Mould in indoor environments. Government of Canada. canada.ca/mould
- Jacobson, B.H., et al. (2008). Effect of prescribed sleep surfaces on back pain and sleep quality in patients with low back pain. Journal of Chiropractic Medicine, 7(1), 1-8.
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