How to Get Pee Stains & Smell Out of a Baby Mattress

It happens to every parent: a leaking nappy, a night with no nappy, or a toddler’s first accident, and suddenly the cot mattress is wet. What should you do if your baby pees on the mattress? How do you get the stain and the smell out without ruining it, or harming your baby? The short answer is to act fast, blot rather than rub, use gentle cleaners, and, most importantly, let the mattress dry completely before it goes back in the cot. This guide gives you a step-by-step method for cleaning baby urine from a cot or cot bed mattress, how to handle old stains and lingering smells, what to avoid, and when it’s time to replace the mattress.

Cleaning Baby Pee from a Mattress at a Glance

What to Do the Moment Baby Pees on the Mattress

1. Take your baby out, clean and change them first.
2. Strip the cot of the sheet, protector, sleeping bag and anything else touched. Wash them as soon as you can, following the labels.
3. Blot straight away. Press clean, dry towels onto the wet patch and keep swapping them for dry ones. Blot, don’t rub: rubbing pushes urine deeper into the mattress.
4. Check how far it went. If the mattress has a waterproof cover and the urine stayed on top, cleaning is easy. If it has soaked through to the core, drying is much harder (see below).

How to Get Baby Urine Out of a Mattress, Step by Step

What you’ll need: clean towels or kitchen roll, white vinegar, a spray bottle, baking soda (bicarbonate of soda), a vacuum with a brush attachment, a damp cloth, and a fan or an open window.

1. Check the care label and any manufacturer instructions. If the cover is removable and washable, remove and wash it according to the label.
2. Blot up the urine with clean towels, pressing firmly from the edges inward.
3. Mix a gentle cleaning spray. One common method is a 50/50 mix of white vinegar and water. Spray it lightly onto the stain. Don’t saturate the mattress.
4. Leave it for 5 to 15 minutes, then blot again with a clean towel.
5. Sprinkle baking soda over the area to take out the smell. Leave it for at least 15 to 20 minutes (some guides suggest hours or overnight for stronger smells), then vacuum it off.
6. Wipe over with a damp cloth if you can still smell vinegar or see residue.
7. Air dry completely. Stand the mattress upright if you can, open a window and point a fan at it. Don’t put the sheet back until it is dry all the way through.

Some guides also suggest steam cleaning. Only do this if the mattress manufacturer says it’s safe, because heat and moisture can damage some mattresses and covers. For everyday care, see our guide on how to clean a baby mattress.

How to Get Pee Smell Out of a Baby Mattress

Smell often lingers when urine has gone beyond the surface. Try these in order:

• Baking soda. Cover the area, leave it for several hours, then vacuum. Repeat if needed.
• Light vinegar spray, then baking soda, as above.
• An enzyme-based cleaner. These are designed to break down the compounds that cause smells. Follow the label, check it’s suitable for a baby’s sleep surface, and spot-test first.
• Fresh air. Open windows and let the mattress air out during the day. Sunlight and moving air help.

Don’t mask the smell with strong perfumes or air fresheners, which you don’t want near a sleeping baby.

How to Remove Old or Set-In Pee Stains

• Dampen the stain lightly with the vinegar solution and let it air dry, then repeat if needed. Deep stains can take several rounds.
• Some guides suggest a hydrogen peroxide and baking soda mix for stubborn stains, but peroxide can damage foam and fabric and discolour covers. We’d only use it if the mattress manufacturer says it’s safe, and never on a mattress your baby will sleep on until it is clean and dry.
• Keep patience in mind: stains can lighten but not disappear completely.

What Not to Do

• Don’t use bleach or harsh chemicals. They can damage the mattress and aren’t suitable for a baby’s sleep surface.
• Don’t rub the stain, which pushes urine deeper.
• Don’t soak the mattress. Water that gets into the core is hard to dry.
• Don’t put a damp mattress back in use. Damp can lead to mould and smells.
• Don’t dry it on a hot radiator or with direct high heat, which can damage materials. Use air and a fan.
• Don’t leave strongly scented products on the surface where your baby’s face will be.

Cleaning Different Types of Cot Mattress

The care of a mattress depends on its materials and cover, so always check the manufacturer’s label. Our guides to the types of baby mattress and what baby mattresses are made of explain what is inside each.

Babymore’s Pocket Sprung, Deluxe Sprung and Eco Fibre mattresses each come with their own care instructions, so check yours.

Can You Prevent It Happening Again?

• Use a fitted, waterproof mattress protector. See our guide to baby mattress protectors.
• Keep a spare protector and sheet ready for night-time changes.
• Check the nappy fit and size before bed. A leaking nappy often means it’s time to size up.
• Use a well-fitting sleeping bag over nappies, and check for gaps. See baby sleeping bag vs blanket.
• For toddlers, a spare set of bedding at hand makes 3am changes easier.

When to Replace the Mattress

Consider replacing a mattress if:

• The smell remains after repeated cleaning.
• The core is wet, damp or smells musty or mouldy.
• The cover is torn or damaged so liquid can get in.
• The surface sags, or has lumps or dips.

The Lullaby Trust recommends a firm, flat mattress in good condition, so a damaged or contaminated one shouldn’t stay in use (see our summary of the Lullaby Trust’s mattress and bedding advice). See our guides on how firm a baby mattress should be, whether to buy a new mattress for each baby and why a good cot mattress is important, and browse our baby mattress range.

Final Thoughts

Accidents are a part of parenting, and a baby mattress can usually be rescued: blot fast, clean gently, deodorise with baking soda and, above all, dry it fully. Keep a spare protector and sheet to hand, and replace the mattress if the smell, damp or damage won’t go away.

Need a fresh start? Browse Babymore’s cot mattresses and cot bed mattresses, or read our mattress guide.

Frequently Asked Questions