Why does my mattress smell? How to get rid or urine, mold and vomit smells

A blue rubber-gloved hand holds a spray bottle aloft a dirty mattress
(Image credit: Getty Images)

If you’ve ever crawled into bed ready for a good night’s sleep only to be greeted by a foul odor, then your mattress is likely to blame. But don’t worry, you’re not alone. Without a decent mattress protector, even the best mattresses with the latest in hypoallergenic properties aren't immune to the slow buildup of sweat, body oils, urine, vomit and even mold, which can all leave your bed smelling far from its best.

And it isn't just old mattresses that can fall foul of an unpleasant odor. Brand new mattresses can smell a little funky, too. However, knowing how to recognize these smells can make all the difference to how to get rid of them.

Here, we'll walk you through 5 common causes of mattress smells, plus how to get rid them. Let's get started.

Why does my mattress smell?

Life (and accidents) happen. And when it does, it's usually your mattress that takes the brunt of any mishaps. Whether it's a bout of illness, an outbreak of mold or just the vague chemical smell of a brand new bed, an occasional unpleasant mattress smell is fairly common.  However, knowing how to recognize each smell can make all the difference to tackling the source of the pong. Here are 5 common causes of mattress odors and what you can do to get rid of them. 

1. Off-gassing 

If you’ve just treated yourself to a new mattress then you may notice a bit of a smell when you unwrap it from its plastic. That’s called off-gassing, which is a process in which VOC’s (volatile organic compounds) are released from the product and in to the air.

Off-gassing is usually present with a lot of synthetic or petroleum-based products including mattresses, carpets and furniture. The odor itself isn’t dangerous but it can be very overpowering. It smells like a strong chemical or plastic smell, and it’s very distinctive - you’ll smell it as soon as your mattress is out of the packing. Memory foam mattresses or those that are tightly compressed during the packing process tend to smell stronger. Off-gassing usually only lasts a few days, but it can be an unpleasant wait.

A pair of hands putting a mattress on a mattress foundation

(Image credit: Getty Images)

How to get rid of the smell

The first thing to do when you unwrap your new mattress is to open all windows and doors to get a good rate of air flow through your room. You could also use fans to circulate the air and remove any VOC's. If you have an air purifier now is the time to plug it in as it’ll work to shift the smell quickly. Also, whilst it can be tempting to put bed sheets straight on the bed don’t. By adding sheets straight on to a new mattress you’ll be trapping those odors in.

2. Mold 

It’s super important to recognize the signs that you have mattress mold so that you can tackle it before the problem takes hold. Mattress mold is a fungus and ,left untreated, will spread rapidly through the fibres of your mattress. It can also spread to your bedding, carpets and other soft furnishings in your home. Mattress mold can also leave you feeling unwell, waking with a stuffy nose, sneezing, itchy eyes and even worsening respiratory issues. Mattress mold also smells unpleasant. Mattress mold has quite a distinctive smell and you’ll notice a strong, musty odor that you may associate with a damp or earthy smell. 

How to get rid of the smell

The first thing you need to open up the windows and ventilate the room well. Then, strip your bed and look for any visible signs of mold. For minor mold issues sprinkle some baking soda on the affected area and leave for several hours before vacuuming it away. It’s really important never to mix baking soda and white vinegar when it comes to tackling mold as this can neutralize the effectiveness of both.

You may also wish to use a solution of white vinegar and water (equal parts) and spot clean any mold spots that are visible. Spray the area and work with a soft bristle brush to remove any mold spores, then using a clean paper towel blot the area to remove any excess liquid. Always leave the mattress to dry out fully before sleeping on it. If the mold is advanced, you may want to consider replacing it entirely.

3. Urine

How to clean a mattress from urine image shows a fresh yellow urine stain on a white mattress surrounded by pink rubber cleaning gloves, a pink pot of bicarbonate of soda and a blush scrubbing brush

(Image credit: Getty Images)

Accidents happen whether it’s potty-training gone wrong or a furry friend getting over-excited. Left untreated, urine on your mattress can cause some seriously bad smells. Although urine has a distinct smell, this alone isn’t responsible for the pungent odor that may be left behind if a mattress isn’t cleaned properly.

Urine contains various chemicals, including urea, uric acid, and ammonia. Without proper attention, these components break down and release an ammonia like gas. Urine also provides a breeding ground of bacteria. These bacteria thrive on the chemicals in urine and it’s what then contributes to that unpleasant smell.  

How to get rid of the smell

In the case of urine, it’s important to act fast. If the accident is fresh then soak up any excess liquid by blotting at the area until your paper towel comes up dry. Don’t rub the area because you’ll risk spreading the contamination.

The best way to get rid of urine smells from your mattress is to create a cleaning solution by mixing warm water with a small amount of either mild detergent or an enzyme-based cleaner. Dab the solution on to the area before wiping the area with a damp cloth.

Be conservative about how much liquid you put on your mattress as some mattress materials such as memory foam can be damaged by excess liquids. Leave to dry fully and then sprinkle a layer of baking soda over the surface of the mattress leaving to stand for at least an hour before vacuuming it away. Remember the longer you leave baking soda on a surface the better it works. 

4. Bed bugs

So bed bugs themselves don’t cause any bad odors, but there are a couple of ways that can contribute to a very noticeable smell on your mattress. Firstly, bed bugs have scent glands that release a pheromone when they are disturbed to alert other bed bugs of the danger. 

This is a musty, sweet, almost almond-like smell. This is stronger when there is a large bed bug infestation present. There’s then a matter of their waste and decomposing bodies. As bed bugs feed on your blood they leave behind fecal matter, and as they fill up, they start to shed their skin. These can accumulate in your mattress and then give off a musty or metallic odor. The metallic odor comes from the iron in our blood and may even smell like rusty old coins. 

How to get rid of the smell

In order to tackle the smell of bed bugs, you have to tackle the infestation. Our guide on how to get rid of bed bugs guide gives step-by-step instructions. However, if the infestation is particularly bad then do reach out for professional help.

Once you’ve tackled the bed bugs, start by vacuuming your mattress thoroughly, paying close attention to the seams, tufts and crevices where the bed bug debris may be left behind. When you empty your vacuum, always do this outside and into a plastic bag which you can then seal and place in an outdoor bin to avoid any cross contamination.

Next, we would advise that you use a high-temperature steam cleaner. Not only will the heat kill any remaining eggs, but the steam will also freshen the area. (If you don’t have a steam cleaner you can steam clean your mattress with an iron.) Use a solution of water and mild dish soap and dab at any brown or red stains left behind until  they eventually lift. 

If the stains are really engrained then swap to hydrogen peroxide. Mix hydrogen peroxide with equal parts water and dab the stain using a clean cloth. Taking another dry, clean cloth then dab the area again to remove any excess moisture. Always leave it to fully dry when your cleaning task is complete. 

5. Vomit

If even the thought of it is enough to make you feel sick, it’s important to tackle vomit odors fast. Vomit is of course a mixture of food particles, stomach acid, digestive enzymes and music. These organic materials will decompose over time and release unpleasant odors. Vomit can also seep deep in to the mattress, especially if not cleaned quickly. Also because stomach acid is a key feature in vomit, this acidity will cause discoloration and actually, eventually, cause the fibres of the mattress to break down. 

Woman cleaning a mattress topper

(Image credit: Shutterstock)

How to get rid of the smell

Acting quickly here is the key. Try to remove as much as the vomit from the sleep surface as possible. Using clean absorbent cloths or paper towels blot up as much of the liquid as you can, don’t rub it as this will spread it further.

Next, you’re going to want to add equal parts water and white vinegar to neutralize and disinfect the area, dip a cloth into the solution, and blot the affected area, being careful not to oversaturate the mattress, which can prevent mold growth. Once you’ve cleaned the area with the cleaning solution, get a damp cloth and clean off any residue.

Leave it to fully dry before grabbing some baking soda and sprinkling this over the affected area. The baking soda will absorb any odors and absorb any excess fluid. Leave for several hours (the longer the better) and vacuum thoroughly to remove the baking soda. If you need to, you can repeat these steps, and since vomit is such a strong odor, it may take more than one attempt. 

How to keep your mattress smelling fresh — 3 top tips

There is nothing better than having a fresh smelling bedroom, and a big part of that is keeping your mattress clean and odor free. Staying on top of your mattress maintenance will get rid of any unpleasant odors.   

 1. Keep your mattress protected

One of the easiest ways to keep your mattress smelling fresh is to invest in one of the best mattress protectors. Mattress protectors provide a barrier between you and your mattress so it will soak up any sweat, body oils, spills or accidents before it even reaches your mattress surface.

And of course, the true beauty of a mattress protector is that it can be taken off your bed and machine washed regularly so your bed will always be clean and fresh. And it's not just liquids that a mattress protector can protect your mattress from, they can also act as a defense against dust mites which thrive on dead skin cells and can trigger allergies and contribute to a musty odor.

One thing to note is that mattress protectors don't last the same amount of time as a mattress, and when they start to age they lose their waterproof capabilities so remember to replace your protector every 2-3 years for full protection. 

2. Vacuum regularly

Woman wearing beige shorts vacuuming her white mattress to get rid of bed bugs

(Image credit: Getty Images)

Running the vacuum over the surface of your bed is one of the best things you can do to keep odors to a minimum. Dust mites, dead skin cells and other dirt can accumulate on your mattress over time. These elements can trap odor-causing particles leaving your mattress stinky.

But vacuuming with the upholstery attachment will remove this debris taking the odor along with it. Dirt and debris, including dust mites, is also a source for bacteria to thrive, this bacteria will cause musty odors. And another really important factor is that by vacuuming regularly you'll clear the layer of dust on your mattress surface which means that your mattress will enjoy better air circulation. In turn not only does that improved airflow help with the evaporation of moisture which traps odors and contributes to mold growth but it'll also keep the mattress cooler.  

3. Clean regularly with baking soda

Baking soda, also known as bicarbonate soda, baking powder or sodium bicarbonate, has a slightly alkaline (basic) pH, which means it absorbs moisture from the air and surrounding surfaces. Moisture is what traps odors so removing it is the key to odor removal. 

Cleaning your mattress with baking soda creates a drier environment meaning it's less conducive to lingering odors. Baking soda can help to neutralize acidic odors so smells that have acidic properties like vomit, sweat, and urine. If you're looking to keep bad smells at bay, sprinkle some baking soda with a couple of drops of essential oils on the surface first. Leave it to dry for a couple of hours before vacuuming it away. Baking soda is also a natural product that is considered to be safe to use around children and pets, plus, it's cost-effective so it's a good budget-friendly solution. 

Rachael Penn

Rachael is a freelance journalist based in South Wales who writes about lifestyle, travel, home and technology. She also reviews a variety of products for various publications including Tom’s Guide, CreativeBloq, IdealHome and Woman&Home. When she’s not writing and reviewing products she can be found walking her Sealyham and West Highland terrier dogs or catching up on some cringe-worthy reality tv.