Baking soda is not a reliable way to kill mice, and there is no proven timeline for how long it takes because the method rarely works as described. The idea has spread widely online, but the science behind it has significant gaps that make it an ineffective approach to a mouse problem.
How Baking Soda Is Supposed to Work
The theory sounds plausible on the surface. When sodium bicarbonate (baking soda) meets stomach acid, it produces carbon dioxide gas. One gram of baking soda generates roughly 260 milliliters of CO2 at body temperature. Since rodents lack the ability to vomit, the trapped gas should theoretically expand in the stomach until it causes fatal internal damage.
Rodents genuinely cannot vomit. A 2013 study published in PLOS ONE confirmed that this is a universal trait across rodent species. Their esophagus can’t shorten the way it does in animals that vomit, their diaphragm muscles are weaker, and their stomach geometry isn’t structured to push contents back up. Most importantly, the brainstem circuitry that triggers vomiting in other mammals simply doesn’t exist in rodents.
So the first half of the claim is true: mice can’t throw up baking soda after eating it. The problem is everything that comes next.
Why It Rarely Works in Practice
The fatal flaw in the baking soda method is that “can’t vomit” doesn’t mean “can’t release gas.” Mice and rats pass gas through normal digestion, just like any other mammal. CO2 produced in the stomach moves through the intestines and exits the body before it can build to dangerous levels. The claim that gas gets permanently “trapped” inside the rodent isn’t supported by digestive science.
Even if gas buildup were possible, the amount of baking soda required makes the method impractical. For baking soda to reach a lethal concentration, a rodent would need to consume it at greater than 50% of what’s in the bait mixture, and in a large enough quantity relative to its body weight. Mice are naturally cautious eaters. They sample small amounts of unfamiliar food and avoid it if the taste or texture seems off. Baking soda has a distinctly salty, bitter flavor that mice tend to reject after an initial taste.
No household food kills mice instantly, safely, or reliably. Most people who try the baking soda method find that mice either ignore the bait entirely or nibble a small amount and move on, leaving the infestation completely untouched.
The Common Bait Recipe and Its Limits
The most popular approach involves mixing one part peanut butter with one part baking soda, then placing small balls of the mixture along walls and near entry points where mice travel. Peanut butter is used because its strong smell and high fat content attract rodents, and its sticky texture makes it harder for mice to separate the baking soda from the food.
In theory, the peanut butter masks the unpleasant taste. In practice, a 50/50 ratio means the bait is half baking soda by volume, which is enough to alter the flavor significantly. Mice have a keen sense of smell and are wired to be suspicious of new food sources. This behavior, called neophobia, is one of the reasons mice have survived alongside humans for thousands of years. They’re exceptionally good at avoiding things that don’t smell or taste right.
Risks to Pets and Children
One reason people turn to baking soda is the assumption that it’s safer than commercial rodent poison. While baking soda is far less toxic than conventional rodenticides, it’s not completely harmless in large amounts. If a dog or cat eats a significant quantity of baking soda bait, it can cause stomach irritation, bloating, vomiting, and diarrhea. In more serious cases, large doses can disrupt sodium levels in the blood and cause dangerous shifts in the body’s acid-base balance.
The risk is relatively low from a small amount of bait, but if you’re placing multiple stations around your home and have curious pets, it’s worth knowing that “non-toxic” isn’t entirely accurate at higher doses.
What Actually Works for Mice
Snap traps remain the most effective and humane option for small infestations. Modern snap traps kill mice in less than a second when set correctly, and they give you visual confirmation that the problem is being addressed. Place them perpendicular to walls with the trigger end facing the baseboard, since mice travel along edges rather than through open spaces.
For larger infestations, enclosed bait stations with commercial rodenticide are more effective but carry real risks to pets, children, and wildlife. These should be placed in tamper-resistant stations and checked regularly.
The most important step is exclusion: sealing the gaps mice use to enter your home. Mice can squeeze through openings as small as a pencil’s width. Steel wool stuffed into gaps around pipes, combined with caulk or expanding foam, blocks the most common entry points. Without sealing these routes, any killing method is temporary because new mice will keep arriving.
If you’ve tried traps and exclusion without success, a professional pest control service can identify entry points you’ve missed and deploy targeted solutions. DIY remedies like baking soda, plaster of Paris mixed with cornmeal, or other homemade concoctions circulate endlessly online, but none have demonstrated consistent results. The time spent experimenting with unreliable methods often allows a small mouse problem to become a much larger one.