The fastest way to get diarrhea smell out of a couch is to remove all solid and liquid waste first, then use an enzymatic cleaner to break down the organic compounds causing the odor. Regular soap and water can handle the visible stain, but the smell lingers because proteins and bacteria are trapped deep in the fabric. Here’s how to tackle both.
Check Your Fabric Cleaning Code First
Before applying any liquid, find the cleaning tag on your couch (usually under the cushions or on the frame). It will have one of four codes that tells you what’s safe to use:
- W: Water-based cleaners only, like mild dish soap and water.
- S: Solvent-based (dry cleaning) products only. Never apply water or steam.
- W/S: Either water-based or solvent cleaners are safe. Start with the gentlest option.
- X: No liquids at all. Vacuum only, and call a professional for stains or odors.
If your couch is coded S or X, skip the water-based steps below and go straight to the section on professional cleaning. Applying water to a solvent-only fabric can cause permanent damage, water rings, or shrinkage.
Remove the Waste Without Spreading It
Start by scraping away any solid matter gently with a flat edge like a spatula or a piece of cardboard. Work from the outside of the stain inward so you don’t push it deeper into the fabric pile. Blot up as much liquid as you can with paper towels or old rags, pressing down firmly without rubbing. Rubbing forces the waste further into the cushion fibers and padding, which is exactly where odor becomes hardest to reach later.
Once you’ve removed everything visible, mix one teaspoon of mild white dish soap into one pint of lukewarm water. Sponge this solution onto the stained area, then blot with a clean absorbent pad. Keep alternating between sponging and blotting until the pad stops picking up discoloration. Then sponge the area with plain water to rinse out all soap residue, and blot dry.
Why the Smell Persists After Cleaning
Diarrhea contains proteins, bacteria, and urea compounds that standard soap doesn’t fully break down. Soap lifts the visible stain off the surface, but microscopic organic matter stays embedded in the fabric weave and the foam cushion underneath. As that residue sits, bacteria continue feeding on it and producing the gases you smell. This is why a couch can look perfectly clean but still stink, especially in warm or humid rooms.
Use an Enzymatic Cleaner for the Odor
Enzymatic cleaners are the most effective tool for eliminating biological odors from upholstery. They contain specialized proteins that bind to specific organic molecules, essentially like a key fitting into a lock, and break them into smaller, odorless components that can be wiped or rinsed away. Protease enzymes target the protein residue from fecal matter, while urease enzymes break down urea. Products marketed for pet accidents (like Nature’s Miracle) work just as well on human waste.
Saturate the affected area thoroughly. The cleaner needs to reach the same depth the waste did, which often means soaking through the fabric into the cushion foam. Spray or pour the enzymatic cleaner onto an absorbent cloth and press it against the stain, leaving it in place for 10 to 15 minutes so the enzymes have time to work. Then sponge with clean water and blot dry. You may need to repeat this process two or three times for severe contamination.
One important note: do not mix enzymatic cleaner with baking soda at the same time. Baking soda can alter the pH enough to deactivate the enzymes, making the product less effective. If you want to use baking soda as a secondary deodorizer, wait until the enzymatic cleaner has fully dried first.
Baking Soda as a Follow-Up
After the enzymatic cleaner has dried completely, sprinkle a generous layer of baking soda over the area and let it sit for several hours or overnight. Baking soda absorbs residual moisture and helps neutralize any remaining surface odor. Vacuum it up thoroughly the next day. This step works well as a finishing touch, but on its own, baking soda and vinegar are not strong enough to eliminate fecal odor that has soaked into cushion foam. They mask smells temporarily without breaking down the organic source.
Do Not Use Steam
It’s tempting to hit the area with a steam cleaner, but high heat permanently bonds protein-based residue into synthetic fibers. This locks in both the stain and the odor in a way that becomes nearly impossible to reverse. Stick with lukewarm or cool water for every step of the cleaning process.
Dry the Cushion Within 48 Hours
A soaked cushion that stays damp too long will develop mold or mildew, adding a second odor problem on top of the first. The EPA recommends drying water-damaged materials within 24 to 48 hours to prevent mold growth. If your cushion covers are removable, unzip them and pull the foam insert out. Stand the foam upright near a fan or in a well-ventilated area. If the covers are not removable, point a fan directly at the wet spot and keep air circulating until the cushion is completely dry to the touch, both on the surface and when you press into it.
Sunlight helps here too. UV light naturally breaks down odor-causing compounds and kills surface bacteria. If you can move the cushion outdoors on a dry day, a few hours of direct sun can make a noticeable difference.
Cleaning Leather Couches
Leather is less porous than fabric, so odor doesn’t penetrate as deeply, but it can still absorb into seams, stitching, and any cracks in the finish. Wipe the surface clean with a damp cloth and mild soap, then apply an enzymatic cleaner sparingly. Test it on a hidden spot first, like the back or underside of a cushion, to make sure it doesn’t discolor the leather. Let the cleaner sit for 10 to 15 minutes, wipe it off, and follow up with a leather conditioner to prevent the area from drying out and cracking.
For leather that still smells after cleaning, leaving the affected cushions in direct sunlight for a day or two can help break down lingering odor compounds.
When to Call a Professional
If you’ve gone through enzymatic cleaning twice and the smell is still there, the waste likely soaked through the fabric into the cushion core or even the couch frame. Home methods can only reach so deep. Professional upholstery cleaners have extraction equipment that can pull contamination out of dense foam and use low-moisture techniques safe for delicate fabrics like silk blends or textured weaves. For couches with non-removable cushions or S and X coded fabrics, professional service is really your only reliable option from the start.
It’s also worth noting that soft surfaces contaminated with fecal matter can harbor pathogens like E. coli and C. difficile. If the person who was sick has a known infection, or if the couch is in a home with young children or immunocompromised individuals, a professional biohazard cleaning service can disinfect the upholstery using EPA-registered products rated for those specific organisms. Standard household disinfectants are not tested or labeled for soft, porous surfaces the way they are for hard ones.