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What is Mouse Poison?

By Elizabeth SanFilippo
Updated: May 16, 2024
Views: 119,945
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When bags of food are gnawed open and droppings litter the kitchen, it often means only one thing: there's a mouse running loose in the house, and it's spreading bacteria and disease. Mice usually infest homes during the colder months as they search for warmth and food. Additionally, mice typically nest inside walls, sometimes making it difficult to trap them using popular mouse snap traps.

Other pest control options include glueboards, live traps, and poison. Poison works well because the smell is similar to that of food. There are typically two kinds of mouse poison on the market, with the first being quick-kill or single-dose poisons in the form of either water or food. The second option is a slow-acting poison that usually takes effect after seven days. Both kinds of poison, including warfarin, diphacinone, pival, chlorophacinone, or fumarin, are usually dyed green for identification purposes.

The quick-kill or single-dose poisons are generally the most popular because they are effective in a short period of time. When successful, they take anywhere from two hours to two days to produce the desired result. Additionally, since they only contain about 2.5 grams of poison (less than 1/100th of an ounce), the amount of poison lying around the house is relatively small. While mouse poison isn't typically hazardous to humans or family pets in small doses, steps should be taken to ensure that your family and your pets do not ingest it. For example, tamper-proof poisons that come in boxes can be used. Additionally, the poison should be placed out of reach of pets and small children.

Even with single-dose poisons, setting out only one box of poison is often ineffective. The recommended amount of poison can range anywhere from two boxes to well up into the double digits, depending on the size of the infestation and what kind of poison is being used. Each set, or box, of mouse poison should be placed at least six feet (about 1.8 meters) apart in areas where mice have been seen or may be nesting. This will increase the chance that the mice take the bait.

Once rodents feed on the poison, they typically get thirsty as their blood vessels constrict and spasm. Some mouse poison products claim that the mice then attempt to search for water by going outside, but this is not always the case. The mice may return to their nest to die, or, depending on how long the poison takes to work, they may die in inconvenient places around the house.

In case of the latter, the mouse should always be disposed of immediately. If the mouse dies inside the walls, it will produce a foul odor. The smell will go away on its own, but to make it a bit more tolerable in the meantime, a fragrant household deodorizer can be used. After a few weeks, the mice should no longer be feeding on the bait, and the poison should be disposed of by throwing it in the garbage.

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Discussion Comments
By anon990784 — On May 09, 2015

@anon356498: Considering you had *rats*, it's unfortunate the poison didn't just kill them for you. But I guess they were just healthy enough you couldn't throw them in a bag to suffocate (and one bag each, so they don't escape and even that's risky if they escape somehow). If a person had time to plan, put on music or the radio while the broom hitting happens, although maybe a person couldn't enjoy that music in quite the same way. Or if they are sick enough, put them in a cardboard box sealed with plastic and a lid, with more poison inside that the rats are trapped with, and check hours or a day later.

Although while I'm typing this, it's so much more work so not to feel bad for directly killing them. I know someone who had to euthanize cats because they didn't get adopted, and it was the hardest thing she's had to do for a job, but she knew it had to be done (likely no room, food, or shelter for it in terms of resources, and can't just let it roam in the city--it would cause a disturbance and might get run over by a car or cause an accident through that).

I'm hoping what you say doesn't make a person too sympathetic, because if the mouse/mice or rats are not dealt with and reproduce, they are bigger problems in terms of numbers when they reproduce, in about 30 days. They will destroy and disturb one's belongings, along with the noise and disturbing peace of mind and sleep. And then once they have gradually claimed the house, they could stretch further.

Anyhow, the earlier they are dealt with, the better. A person won't have to deal with offspring, so smaller numbers to deal with them.

By angelk9 — On Apr 01, 2015

To all of you: I feel your pain. I own two RV'S and this winter my 20 year old tells me mom I found rat poop in the pace arrow. I found insulation and tiny pieces of wire in the cabinet and on the counter.

Well, because we are traveling I bought poison pellets and placed them in the kitchen area. Then in my brand new RV Rexhall I placed it in the attic area since I figured if they go anywhere it would be there because we have animals and we keep the doors shut.

So then, we went to bed that night. I swear it had to be a whole army unit in the headliner of the roof of the RV. Because it was a new RV I didn't think I would have any. I'd never heard any before -- just thought I'd put them there, just in case. This morning the whole container is empty Now I'm worried because if they die in the roof/headliner, I can't take it down.

Hubby said no worries. If we hit the brakes really fast, if we hear rattling across the roof it's just the pellets and if it's clunking, it's the bodies rolling across the ceiling.

Mind you I am a military spouse I am used to hearing everything. So my son said put a boa in the RV. Hell no! That's two things I hate in an enclosed space. I hope they eat the bait and go outside to find water. I am so, so, so, so freaked out knowing they're above my head. I have no bad feeling on killing them they are a danger to me due to viruses and many other things besides eating my wires maybe cause a fire. So here is to the last dinner they will eat. May your life end the way you ate my RV.

By anon356498 — On Nov 25, 2013

Several years ago we had a family of rats move in, so I put out some rat poison. Unfortunately it made all five sick. They were in the kitchen. It was a mama, daddy and three babies. I had to kill them with a broom. Each time I hit them they would say tweet, tweet. It was horrible.

I hate mice and rats because they are so nasty and they do carry diseases. However, it was a horrible thing to have to do. I hate hurting anything, and I cringe to think of the pain I caused them.

By anon328865 — On Apr 06, 2013

Also, for anyone living in Canada or somewhere the cities have released new compost bins and some have very small holes in the bottom and mice and other creatures of this sort commonly use this as a food source because they are always close to the house and shelter is usually close by for hiding.

Nine times out of 10, if they are outside your house, they will find a way in if there is one, and in the house I was renting, which I vacated, they set up a nest behind the furnace and used the walls and attack for traveling.

I will say one thing for all fellow renters: When renting, most sign a one-year rental contract which will require the landlord to get pest control, but if the house is older, it will require a heavy investment, which some will not do, so if you are desperate for a way out and have no grounds to leave and have a not so nice landlord (I would use a more unsuitable word for mine), simply get a note from your doctor saying how much sleep you are losing and sick you feel and how your work and personal life have been affected. Don't clearly state if your landlord will not give you the reimbursement back for a deposit or compensated rent money back, you will have to go to small claims court by your decision or the landlord's. That will quickly solve your problem and to put a cherry on the top, a letter from you employer stating your home problems have affected your work performance will help, too. Problem solved. Please pass it on. God bless.

By anon325532 — On Mar 16, 2013

Well, at least now I have an idea of why I've suddenly started finding dead mice in my live traps every day or two. I assume they're going over to my neighbor's yard at night and eating poison cubes or something.

For those using them: make sure you don't use them if there are pets or kids anywhere nearby! Rodent poisons have a scent and flavor that appeals to pets and little kids enough that they'll often find a way to reach it, and you'd have to be incredibly lucky if it only makes them extremely sick rather than being fatal.

By anon296016 — On Oct 09, 2012

We have had mice in our house. We have seen and caught several of them. They seem to come to the same place for food all the time, under the sink where the compost is kept. I put out a box of poison seeds and it took a few days for it to be gone. They left behind a mess.

When I hadn't seen any sign of mice for a few days, I cleaned and disinfected the cupboard. A couple of days later I saw more droppings so I put out the last box of poison. It was empty the next morning, with no mess left this time. Then I bought some green blocks of poison. I put one in the same place and the next day it was gone. Not a crumb left. Then I put out two more. They were untouched for a day but suddenly one of them was gone, the other one undisturbed.

Why would this be happening? How could mice carry away something that is almost the size they are? Could it be something bigger than mice in here now?

By anon289650 — On Sep 05, 2012

If you don't want to use poison you must eliminate all sources of water and food. To keep them out find any and every tiny opening into your house/apartment. Around water pipes is an easy way for them to get in, so use triple expanding foam for larger areas and stuff plain steel wool into smaller areas.

Make sure you clean under and behind the fridge at least two times a year. Put boxed foods in tins or thick plastic. Empty the crumb catch of your toaster. If you have many, then do all of this and put food and water outside. People think I'm kidding around when I say I don't get squirrels in my house over the winter because I do put out sunflower seeds and a few peanuts. But while it is true that the "wild" animals would much rather live outside of our homes, they are no fools when it comes to survival. How long would you ignore free room and board?

By anon274750 — On Jun 13, 2012

I found two mice in my bedroom. They are not eating the poison at all.

By anon269094 — On May 16, 2012

DCon works as advertised. But it can be tough to watch. Had a critter nibble on the bait for several days. On the fifth day, I finally saw the critter at the foot of my sofa chair. It was still alive, but dying. Within an hour after that, it was dead. It was not pleasant to watch like that, knowing that I put the bait out. But it's not safe to have wild critters running around the house like that.

Bottom line is it works but I wouldn't recommend it for the faint of heart.

By anon253463 — On Mar 09, 2012

They don't go outside! That must be a "sales pitch". I put two boxes in my garage, one being between the washer and dryer. About two weeks later, I was doing laundry and as the water was filling up, and there was a mouse swimming in it. The next incident was when I smelled a dead one and realized it was under the fridge. I pulled the fridge out, but still couldn't find it, but of course smell was worse. Lo and behold, I pulled the drain pan out and wow! Kangaroo mouse. I am such a "girl" about that kind of stuff.

My feedback as far as the way they die is this: they do get thirsty, look for water. But this sucker ate the d-con outside and then came in. So my experience is different from everyone else's. Therefore, who knows really, except for the rodent. Right?

By anon195750 — On Jul 12, 2011

Dcon works but it doesn't give you peace of mind unless you find the critter. About three weeks ago, I saw two mice inside. I put down two boxes of dcon and the critters took a sizeable portion of the bait.

Five days later, I found one of the mice dead. I don't know what happened to the other one. I haven't heard any activity, I haven't smelled any foul odor (of a mouse dead inside the walls), and the bait hasn't been touched since then. I hope the other one just went outside, but not knowing if it died, left or just went hibernating elsewhere is not soothing, not to mention the feeling that it might return any minute or one of its buddies might come in from the same place wherever those other two entered from.

The product works but it doesn't really give you peace of mind unless you find the critter dead.

By anon177522 — On May 18, 2011

I've been living in a 15-unit apartment complex for the past eight years. About a year after I moved in, a friend moved in about 12 units down. One day I saw him at a restaurant and he said "I'm not a slob, but do you have rats in your unit?" He said he was getting rats. I get the common bug pests now and then (spiders, centipedes and now stink bugs) but I had never seen any rats. He moved out eight months later so I don't know if he ever solved the problem.

That all changed when I saw my first rat/mouse a couple weeks ago. It totally freaked me out. I laid down several boxes of d-con bait, but it looked like it either didn't take the pellets or ate maybe a couple small pellets at most. I then bought a few d-con mouse traps, baiting them with peanut butter, and those remained untouched as well.

I also made sure all the garbage was out of the unit. However, the night before, I purchased a salad (which I ate all of) and when I was done with it, I put the empty/remaining salad dressing container in the plastic container and double tied the plastic bag it in came in and put it in my kitchen trash can. My trash can is three feet high. (I didn't mean to leave any garbage in there, but it's habit to do so).

When I came home from work the next day, I heard a rumbling noise in my kitchen. I assumed the rodent had gotten into one of my cabinets, but after a minute or so, I noticed the plastic bag in the garbage can moving up and down! I was totally shocked! It's no exaggeration when you read that these rodents can jump and get into the tiniest places. Somehow the rodent had jumped into the trash can, into the tiny hole at the top of the plastic bag (that I thought was tied shut pretty good) and was eating what was left of the salad dressing.

It was a very small critter, about the size of the palm of my hand at most. Even after I took it far away outside and opened the bag, I still couldn't see it. Finally I saw it and it ran away harmlessly out of the bag and across the street.

I had hoped I was in the clear at that point, but I was worried about the warning that "if you see one, you probably have several." Sure enough, four hours later, I happened to notice another one scurrying across the room. Now I'm back to the drawing board. My next try is to mix the d-con pellets with some of that same salad dressing. But I'll definitely be back at the hardware store tonight buying another form of rodent control. It is disturbing to me that nothing better than the trash has worked at this point and that's certainly not an avenue I really want to take again.

By anon177219 — On May 17, 2011

i have been finding mice in my new flat. My neighbours have also found mice. I'm so scared I've moved back home. i have put mouse poisoning down and it's all been eaten, but yet i still see them at night. The worst is knowing they are in the same room as I am and how fast they move!

By anon161179 — On Mar 18, 2011

We own a trailer home in the forest. It is used primarily in the summer months for weekend getaways and is closed down for the winter months. The field mice that visit, or live in our trailer are fascinating. Though we realize that it is impossible to permanently rid the place of rodents, we do try to minimize their effects by using glue traps and poison pellets. In the case of poison pellets, these little creatures hoard them by moving them to unusual places. Once, as I pulled the last tissue out of a kleenex box I noticed a good handful of pellets in the bottom of the box (the taller square-type box).

Some mouse was making trips from the pellet container on the floor across the room, and carrying the pellets to the tissue box. Somehow they would jump onto the box, deposit the pellet then go back, over and over, to do the same procedure! It's almost as though they were striking out in retaliation for us trying to poison them! I would imagine that in this process they must have consumed enough to at least make them sick!

We found a similar situation on the kitchen table top. An artificial plant in a clear vase had another handful of pellets. With all the incredible effort, these mice must feel they are doing something similar to building the great pyramids. I would love to be able to film them to learn their process! The battle continues!

By anon153935 — On Feb 18, 2011

The rat king has returned! One time it ran by me when i was sitting on the couch. What happens when mice eat the poison? do they just die in your walls, or are we going to find them by the poison? we put mouse poison out and now there are green poops everywhere! we have a plastic rat on our tv to keep us aware.

By anon149213 — On Feb 03, 2011

I use the catch and release traps and they have worked so far, have caught 5! But I'm tired of having to go to a far away field as I don't have a car. Now, I want to use poison.

Is it inhumane to put the poison in the catch and release trap so the mice die in a contained area and I can dispose of them properly? I hate for them to be dying in my walls!

By anon147942 — On Jan 31, 2011

well I have mice and we had the orkin man come and he put these black boxes with poison in them and tonight I heard one inside the box chewing but then after awhile I didn't hear it anymore. does that mean it's dead?

and to the person who had the pellets in their bed my hubby would have been planning my funeral because I would have had a heart attack lol because I hate them. my daughter has a hamster and I won't go near it or touch it. lol

By anon146666 — On Jan 26, 2011

to anon110003 comment number 8. The shredding is a good, good sign! That's how mice eat. They are very messy, if you see pellet pieces it means they are eating the poison!

Good luck to everyone. These little mice are very cute but are a very big hassle. It is sad to need to kill them, but they do not make good house pets!

By anon137118 — On Dec 26, 2010

Poison is the way to go. I started with non-lethal metal traps with the intent of setting the critters free. I never caught any and within a few months they had babies. I then used glue traps, sometimes cutting the edges and lining them up to form an impenetrable boarder. This worked and sometimes I caught three or four mice, I would awake to the sounds of squealing and see them bleeding on the glue. Only problem was that there were more and more and more.

I started going crazy. I would drown them in the toilet, throw things at them, and in the process, I would break things around the house. I had come a long way from the tree hugger who did not want to kill them. Then one day I called an exterminator. He placed poison all over the house and in the basement.

Within a month there were no more droppings and no more mice. One day I decided to sell our sofabed which sat in the living room and had never been opened. When I opened it to clean any crumbs and objects that might have gotten caught in it I was shocked to see it caked with a half inch deep layer of mouse droppings from one end to the other. It made me sick and I just threw the sofa out.

It has been three years and now they are back. Poison! Poison!

By anon135966 — On Dec 21, 2010

We've had mice for about five weeks. we have caught one with a trap but haven't caught any since. I hear them in my bedroom ceiling but have never seen any droppings.

They're driving me mad and I wake up in the middle of the night hearing them scurrying around up there.

Last night, we put poison down in the loft and have heard loads of activity ever since. I'm hoping that mummy mouse has found the pellets and is taking them back to the nest. Fingers crossed.

By anon127898 — On Nov 17, 2010

Try mixing the Dcon baits with a little cheap peanut butter for added effect, since mice and rats find it irresistible. Also, put a few baits outdoors as well as indoors to control the critters outside, before they move in for the winter. Just make sure that humans and nontarget animals can't get at the bait.

By sboreland28 — On Nov 17, 2010

Two days ago i found a mouse behind my freezer. I've got traps down but they've not yet done the job. I've found where it seems to be living. I'm wanting to try some sort of poison. the thing that worries me is if it goes back into the wall and dies. Help. Thank you!

By anon119186 — On Oct 16, 2010

I'm so glad to hear that I'm not going crazy after all. I crawled into bed last night to find a large pile of D-con under my pillow! I assume that can only mean one thing - that the mice are moving the D-con to more comfortable locations to eat: under my pillow!

By anon110003 — On Sep 10, 2010

I put down some poison in my room a couple of months ago, green/blue looking pellets because we have had mice in the house for months (I'm in a house share). Last night I woke up to hear mice eating the pellets. When I turned on the light it ran out of the room. I thought OK at least it's gone. Went back to bed, heard another one chewing on the pellets. I don't think it was the same one otherwise I would have heard it come back in.

So anyway, I turned on the light it ran out of the room. Same thing happened again and it seemed to be a third mouse on the pellets, same story, turned on the light and it ran out. So I decided to try and sleep and deal with the mess in the morning.

This morning when I was cleaning I found all the pellets from one location had been shredded. I checked the other location and the mice seem to have shredded one or two from that location.

My question is, since the pellets were just shredded, does that mean the mice wouldn't have ingested them which means they won't die? Does anyone know whether it makes a difference whether they are shredded or not?

I really hope they die. They have been stressing me out for ages.

I don't know if this has been going on for days or weeks and I just had not realized. I often wear earplugs when I'm sleeping so I don't hear any noise during the night. The fact that the other location only had a few shreds might mean it has been going on for ages without my realisation?

By anon91820 — On Jun 24, 2010

A few years ago I had a tenant who brought in mice and I put out the blocks. I noticed they weren't being eaten. So I took some left over garlic sauce from dinner and poured it over the baits and put them out again. The next day they were half eaten and then I saw green mouse droppings. After a few weeks the mice were gone. I saw a few droppings last night so I am on my way to get more cubes. I'm glad I saw the posts because I was going to get the pellets. Now I see its best to stick to the cubes.

By anon58272 — On Dec 31, 2009

I have had the same problem with them moving them inside the house from an outside storage room. I have children so it is especially concerning for me.

I have stopped buying the pellets and have now started purchasing the bait blocks. They are large and cannot be stored or hoarded somewhere in the house. I have found them in some odd places, like inside a small box that I had in my bathroom linen closet, and have found some on my living room floor early in the morning.

My guess is that they are trying to nest somewhere or carry them back to their nests and drop them. Try the blocks maybe it will solve your problem. I like them much better.

By anon56455 — On Dec 15, 2009

My advise to you both is get a cat. Not a kitten. A grown cat 2-3 years old. One that is grown and ready to hunt! Which is exactly what I did last winter when my house became infested with mice. I'd lie awake and hear them scurrying around in my walls and sometimes I'd hear them squeaking like they were fighting. It made my skin crawl and was literally driving me insane.

So I went to the nearest animal shelter and adopted a super sweet four year old pure white male cat, who was ready to hunt! I'll tell you what: he spent two days getting used to me and the house and after that he was drawn to my kitchen, because he could smell them. He spent hours just sitting in there listening to them in the walls, waiting. I mean hours.

Finally he started catching them, one after another, over and over. He killed so many so fast in one week we started seeing really small babies coming out in search of food since he must have killed their adult parents.

But yes that's my story. I still have my cat going on the second winter. He kills them as fast at they come in to my house. He has a nose for them lol. He's caught three so far this winter. They don't last long here at all. My advice: get a cat.

By anon52662 — On Nov 16, 2009

In response to anon22498, OMG, in your bed? The mice are obviously hoarding the pellets, but I'd think they'd take them to their nests, not randomly all over the house. Do you eat food in bed and have crumbs that might attract them? They love chocolate.

I found a couple of "nests" under my living room furniture last winter, mainly with sunflower seeds and pine needles. Now this fall I hear them in the walls and in the attic. The mouse poison I place in the attic disappears, so hopefully they're eating it and not hoarding it. I'm scared like you.

Sounds like a bad infestation.

By anon22498 — On Dec 04, 2008

I am finding the green mice poison d-con pellets all over my house in strange places. One day there was a pile of about 20-30 pellets in the middle of a stair. I found a scattering under the couch yesterday. I have found them in bed and in the pull out couch. I have no droppings anywhere but I am sure they are in the walls as I hear running in the middle of the night. I have put out more d-con but somehow it is being moved. Any ideas or suggestions. I am particularly worried/scared about finding some between the bed covers and the pull out couch.

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