How to Get Rid of a Smell on Your Crib Mattress: Causes and Fixes

Quick answer

A smell from your crib mattress is usually harmless—often from off-gassing of new materials or a waterproof cover. To fix it, air it out in a well-ventilated room for 24–48 hours, and if the smell persists, try a gentle baking soda treatment. For a waterproof cover that smells, wash it according to care instructions and let it dry completely before putting it back on the mattress.

You unbox a new crib mattress and notice a distinct smell—or maybe your toddler's mattress has developed an odor over time. It's a common concern for parents, and it's natural to worry about what your baby is breathing in. The good news: most crib mattress smells are temporary and harmless, but it's smart to know the cause and how to address it safely.

In this guide, we'll walk you through the likely reasons your crib mattress smells, from off-gassing to moisture issues, and give you clear, step-by-step solutions to deodorize it without harsh chemicals. We'll also flag when you should stop DIY fixes and consider a replacement.

Common Causes of Crib Mattress Smells

New mattresses often have a 'new mattress smell' because of off-gassing—the release of volatile organic compounds (VOCs) from materials like foam, adhesives, and water-resistant barriers. While many crib mattresses are designed to be low-VOC, some odor is normal and typically fades within a few days to a couple of weeks.

Another culprit is the waterproof cover. Many crib mattresses come with a vinyl or polyurethane cover to protect against accidents, but these materials can emit a smell, especially when new or if they're not breathable. If you've added a separate mattress cover, that could be the source too.

Moisture is a common cause of musty or mildew smells. If a mattress gets wet and isn't dried thoroughly, bacteria and mold can grow, leading to a persistent odor. This is more likely with older mattresses or after accidents that aren't cleaned up promptly.

• Check if the smell is stronger when the mattress is covered—this might point to the cover itself.
• Consider the age of the mattress: new smells are usually off-gassing, while old smells are often moisture-related.

How to Deodorize a Crib Mattress Safely

Start by airing out the mattress. Place it in a well-ventilated room, ideally near an open window, and let it air for 24–48 hours. If possible, stand it on its side to allow airflow on all surfaces. This simple step often resolves off-gassing smells.

If the smell persists, sprinkle a thin layer of baking soda over the entire mattress surface and let it sit for several hours—overnight is even better. Baking soda naturally absorbs odors. Then vacuum it off thoroughly using an upholstery attachment. This is a safe, non-toxic method for a baby's mattress.

For stubborn smells, you can create a mild solution of equal parts water and white vinegar in a spray bottle. Lightly mist the mattress (don't soak it), then blot with a clean cloth and let it dry completely. Vinegar is a natural deodorizer and safe for most mattresses, but test on a small area first.

• Never use harsh chemical cleaners or bleach on a crib mattress, as residues can be harmful to your baby.
• Always allow the mattress to dry fully before putting sheets back on to prevent mold growth.

Washing and Caring for a Waterproof Mattress Cover

If the smell comes from a waterproof mattress cover, washing it can help. Many covers are machine washable, but always check the care label. Use a gentle cycle with mild detergent and avoid fabric softeners, which can break down the waterproofing. After washing, air dry or tumble dry on low, but make sure it's completely dry before putting it back on the mattress.

Some waterproof covers are made from materials like organic cotton with a polyurethane backing, which are more breathable than vinyl and less likely to trap odors. If your cover smells despite washing, or if it's made of vinyl, you might consider replacing it with a more breathable option.

• Wash a new waterproof cover before first use to reduce any factory smell.
• If the cover is not machine washable, wipe it down with a damp cloth and mild soap, then air dry.

Diagnosing the Smell: Symptom, Cause, and Action

• Symptom: A chemical or 'new' smell when you first unpack the mattress. This is likely off-gassing from new materials.
• Likely cause: VOCs from foam, adhesives, or waterproof barriers. Usually harmless and temporary.
• Corrective action: Air out the mattress in a well-ventilated room for 24–48 hours. If the smell lingers, use a baking soda treatment. Most smells fade within a week.
• Stop or choose another option: If the smell persists after airing and cleaning, or if it's musty (indicating mold), stop using the mattress and consider replacing it. A persistent odor may signal a deeper issue that DIY fixes can't solve.

Products That Can Help With Crib Mattress Smells

• Naturepedic Breathable, Waterproof Mattress Cover: This cover features an organic cotton surface, waterproof backing, and is machine washable. It is Greenguard Gold Certified and vinyl-, PVC-, and polyurethane-free. A breathable, non-toxic cover reduces the chance of off-gassing smells and is easier to keep fresh with regular washing.
• Stripes Baby Quilt: Made from organic cotton and hand-stitched in Brazil, this lightweight quilt is soft and cozy for snuggles and play. Using a breathable organic cotton quilt on top of the mattress adds a soft layer that's easy to wash and helps keep the sleep surface clean and fresh.

A smelly crib mattress is usually a temporary issue that you can resolve with fresh air and a little baking soda. By understanding the cause—whether it's off-gassing from new materials or a waterproof cover—you can take the right steps to keep your baby's sleep space fresh and safe. If the odor doesn't go away, trust your instincts and replace the mattress to ensure a healthy sleeping environment.