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Mouse and Rat Poison: What They're Not Telling Us

Connie knows how very important natural habitats are. That's why she cares about safer rodent-removal practices.

This article will break down the perils of first- and second-generation rodenticides and how you can control your rodent problem with less dangerous measures.

This article will break down the perils of first- and second-generation rodenticides and how you can control your rodent problem with less dangerous measures.

The Dangers of Mouse Poison and Rodenticides

Most people can identify with the scenario of finding a mouse in their home and wanting to do whatever it takes to remove it. Little do these people know that the warnings on rodent-killing products should also read: "Keep out of reach of all things great and small, bright and beautiful," because they really are "death in a box." The manufacturers are not required to divulge, however, just exactly how lethal their toxic chemical concoction really is.

This article will provide extensive information about just what exactly is in these rodenticides, why you should think twice about using them, and what other options you have to solve your rodent problems.

What Are Rodents?

Rodents are small mammals that share "teeth" in common. That is, they have both upper and lower incisors that continue to grow. As you might imagine, to keep their teeth from overgrowing, they must continually gnaw on something.

Unfortunately, that usually means roots, fruits, seeds, and plant stems fall victim to their dental needs. It can also mean your walls, floors, and household electric and vehicle wiring will suffer expensive damage. There are a few rodents that are the exception to the rule, however, and only eat fish or insects.

In my neck of the woods, the rodents include deer mice, brown mice, voles, moles, possums, black and brown rats, grey, red, and flying squirrels, chipmunks, wild mink, ferrets, and gophers. I'm sure there are others; I just haven't seen them yet!

Why Do Rodents Pose a Threat to Us?

Rats and mice can spread diseases, like hantavirus (see table below). They carry lice, fleas, mites, ticks, and other tiny critters on their skin and fur.

If you own a vineyard, for example, gophers can mean big bucks down the drain. Their burrowing messes up your root and soil systems, and they gnaw on your grapevine stems, causing the plants to die.

As you can see, getting rid of rodents in our homes and on our farms is beneficial in many ways.

Diseases Caused by Rats and Mice in North and South America

Information provided by the Centers for Disease Control and Prevention.

RodentDiseaseHow It's Spread

deer and white-footed mouse

hantavirus pulmonary syndrome

dust contaminated with rodent urine or droppings

rats and mice


ingesting food or water contaminated by rodent urine

house mice

lymphocytic choriomeningitis

contaminated dust

rats and mice

rat-bite fever

bite from an infected rodent

rats and mice


contaminated food or water

rats and mice


handling an infected dead animal

How First-Generation Rodent Poisons Work

Also known as rodenticides, first-generation rodent poisons contain chemicals that specifically inhibit vitamin K, which prevents blood from clotting naturally. Warfarin is the key ingredient.

If you've ever had surgery and had to take a blood thinner to prevent clots afterward, then you have most likely ingested that chemical. When used to kill rodents, their blood becomes so thin that it cannot carry necessary oxygen to the brain, nervous system, and organs—and the animal dies.

Though first-generation concoctions have a good kill rate, it was believed that the critters might develop a tolerance to them. Thus, the World Health Organization became involved and requested the manufacture of something much more toxic. Imperial Chemical Industries of London obliged and developed the new "super rodent killer," also known as second-generation rodenticide.

How Second-Generation Rodenticides Work

The second-generation mouse and rat poisons kill much more slowly but employ the same strategy: vitamin K is inhibited to keep blood from clotting. That means the rodent will probably go back for seconds, thirds, fourths, and so on. By the time the rodent actually dies, it will have ingested many times the lethal dose. They then become weapons of collateral destruction.

Why Second-Generation Rodenticides Are So Dangerous

One of the main problems with this method is that there is nothing quite as tempting as a rat that is stumbling and slow to run away. As a consequence, any of their natural predators that come across this weakened animal in search of a snack will also be poisoned after ingesting them.

This includes owls, hawks, vultures, eagles, raccoons, foxes, and yes, even the family dog or cat! Wild birds that feed on rodents, as well as our pets, are especially vulnerable, but all animals die horribly excruciating deaths after ingesting second-generation rodent killers.

Rising Tolerance Levels and Collateral Damage

The rate of rodent kill is high for the first two years or so when using second-generation poisons. After that, however, the tolerance level is quickly reached, and rodents multiply faster than ever!

Moreover, there is no backup plan. Birds of prey that eat the poisoned rodents—or feed them to their young—develop tumors, bleed through their skin, become too lethargic to hunt, and either die from the effects of the poison or starve to death.

Our natural biological controls, specifically owls, hawks, vultures, badgers, coyotes, mountain lions, bobcats, and skunks, among others, are being killed off by poison at an alarming rate. In fact, 79.1 percent of birds and mammals tested by Wildcare, a rehabilitation facility in San Rafael, California, came up positive for rodenticides, according to Audubon Magazine.

The Dangers Posed to Our Children and Our Families

Our precious children are being poisoned by this stuff as well. Keeping the bait out of their immediate reach is no guarantee kids will not come in contact with it.

The rodents are so slow to die that they move around the house for days, all the while trailing the bait along with them on their feet, tails, and fur. This stuff remains stored in the liver, so there’s no telling how far-reaching its effects will be on our future generations.

Veterinarians will tell you about the high poisoning rate in the pets they see due to the use of these lethal chemical concoctions. Our pets are members of our family. Losing them this way and knowing it could have been prevented is just unbearable. It’s a very sad lesson to be learned.

Second-generation rodenticides pose a significant risk to pets and wildlife in the surrounding area.

Second-generation rodenticides pose a significant risk to pets and wildlife in the surrounding area.

Efforts Taken to Stop the Use of Second-Generation Rodent Poisons

In 2008, the Environmental Protection Agency declared, "Second-Generation Rodenticides posed an unreasonable risk to children, pets and wildlife." It gave manufacturers three years to stop selling the more lethal rodent poison directly to households.

New York City is solidly behind this order and agrees that the use of second-generation rodenticides as a rodent control is unnecessarily risky to humans and wildlife. This is a strong endorsement coming from a rodent-infested metropolitan area!

Unfortunately, the EPA left a giant loophole you could drive a train through large-quantity sales, such as those to farmers, and tamper-proof bait boxes that are used by exterminators were exempted from the cease-to-sell order. The result is that predators and scavengers are just as poisoned from those rodents that have eaten from exterminators' "sealed bait boxes," or bait set out by farmers.

To date, 26 out of 29 manufacturers of second-generation mouse and rat baits have complied with the EPA order. The three that have refused to cease production of these poisons are:

  1. Spectrum Group, a maker of pet care products (ironically) as well as Hot Shot mouse and rat baits with the active ingredient brodifacoum, which is the most deadly to pets and wildlife.
  2. Liphatech, producer of Generation, Maki, Rozol, and d-Con, which contains brodifacoum. They also make Lysol, Woolite, and French's Mustard!
  3. Reckitt Benckiser, which is trying to drag this out in court, while innocents continue to die.

How We Can Help Stop the Killing of Our Natural Rodent Controls

  • Use safe alternatives to poison baits, like old-fashioned multi-use snap traps or covered disposable snap traps—so you don’t have to see or handle the dead critter—which are available at the same store where the toxic chemicals are found.
  • You can also opt for using humane pest traps—that’s what I use. Add peanut butter as bait, and take the live rodent to a location at least a mile away to release. You don’t want them to end up back at your house! Also, do make sure the release location is away from homes or farms. Be sure not to make problems for someone else!
  • Electronic rodent killers are also an option. Though these seem to have mixed results depending upon where they are placed in conjunction with the actual rodent point of entry. More than one is usually needed to cover the area in question. Quite often, our attic is mouse central, especially in the autumn and springtime. In order to make sure the whole area will receive the electronic shockwave that is the rodent repellent, we need to set up six devices. The use of a surge protector with six outlets is convenient in this case.

Avoid Using Any Second-Generation Rodent Killers

Make a habit of reading labels. Do not buy rodent baits that contain any of these active ingredients:

  • brodifacoum (which is especially harmful to pets and birds)
  • bromadiolone
  • difethialone
  • difenacoum

If you see any of these second-generation killers on the store shelves, please immediately talk to the store manager. Alert them to the risks these indiscriminate killers pose to our children, pets, and wildlife. Urge their immediate removal!

You can also contact the EPA and caution them to cancel general-use registration of second-generation rodenticides.

Setting up a barn owl nesting box around your home is a great way to use natural predators to control rodent populations.

Setting up a barn owl nesting box around your home is a great way to use natural predators to control rodent populations.

Install Barn Owl Nesting Boxes Around Your Home

Owls and raptors, in general, are extremely efficient at reducing rodent populations without using toxic means. You can increase the likelihood of these natural predators helping out your cause by adding barn owl nesting boxes around your home. Barn owls, in particular, benefit from nest boxes and are non-territorial. If there is plenty of food, there will be no squabblers—just a rodent feast!

You can even help support R.A.T.S. (Raptors Are The Solution) or the Hungry Owl Project. The latter is an organization based in California, but it can provide information about whether owl nesting boxes would benefit your situation. Their volunteers build, distribute, install, monitor, and clean owl nest boxes to aid farmers with their rodent infestations. They have been hugely successful.

Use Peppermint Oil as a Repellent

I have successfully used peppermint oil from the grocery store to keep mice out of my house.

Just use cotton balls and saturate them with the oil. Place them at possible entry points in your attic, basement, or wherever rodents are a problem. You will have to remember to add more freshly saturated cotton balls every couple of weeks or so. But hey, the place smells like Christmas all the time—and it's totally non-toxic too!

Forewarned Is Forearmed

Make sure to relay this information to anyone who might be considering the use of any rodenticide. You will be saving countless innocent lives and helping to restore the natural balance.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

What Do You Use to Control Rodents?

Emma on September 20, 2018:

Ferrets are not rodents. They are part of the Family Mustelidae and Genus Mustela. This means they are more closely related to weasels and otters. Therefore they are not rodents. Please stop putting out false information on these animals. They have been domesticated for 2,000 years and are not capable of living out in the wild. (except for the black footed ferret which is not domesticated but fairly sure they're not common either) They are quite loving and fun to be around.

stephanie on February 06, 2018:

Possums actually are from the marsupial family. They do not have the same type of teeth that a rodent has. They have 50 ethnic that do not require them to chew because they do not continuesly grow. They are not destructive creatures and are really quite harmless. They actually feed on rodents. Too many people put out false information on these guys giving them a bad rep.

Marianne on November 02, 2017:

Been using (i think) Rat X. NON POISONOUS to others. Have dogs. Door open 80% of time. Have ultrasonic. Seems they are use to original . What poisons can be used in doors and not kill pets

Connie Smith (author) from Southern Tier New York State on August 21, 2013:

pstraubie, you are so right--this is an alarming thing for sure. The world over, toxic pesticides show up in every species on this planet, including humans! The government is well aware of the situation and chooses to look the other way in favor of the big-money interests. It has long been a pet peeve of mine, so I will keep on telling everyone how much damage these pesticides have done and continue to do. Thanks for your superior support and excellent comments.

I have a lot of peppermint growing out back, just in case you need some! LOL

Thanks as always for stopping by, and for the Angels, who are very much appreciated, as are you, my friend ;) Pearl

Patricia Scott from North Central Florida on August 21, 2013:

This is so alarming Pearl. And it really is not common knowledge. I know it is important to control rodents but I hate to think they die a horrible death.

I like your suggestion. If I am ever plagued by these critters I will give peppermint oil a try.

thanks for being a voice for these creatures. Angels are on the way ps

Connie Smith (author) from Southern Tier New York State on April 15, 2013:

LongTimeMother, so glad you stopped by! Yes, even though they are a nuisance, I prefer the kinder way to dispense with mice. The cage trap has had a lot of use over the years for sure! Thanks for the supportive comment, and the vote; they are very much appreciated!

;) Pearl

LongTimeMother from Australia on April 15, 2013:

I have a cage trap a little different to yours. Much kinder way to catch the mice. Another brilliant hub. Voted up.

Connie Smith (author) from Southern Tier New York State on March 10, 2013:

Hi Mommy! I'm so glad you found this useful. It is so important for all of us to know exactly what we are buying, and to hold these big corporations accountable for their actions!

Thank you very much for commenting, bookmarking and sharing. The more we can get the word out, the better for all of us. I appreciate the Vote as well. ;)


Michelle Clairday from Arkansas on March 10, 2013:

Very interesting and informative. Voted up, shared, and bookmarking just in case.

Connie Smith (author) from Southern Tier New York State on March 10, 2013:

Peggy, you are the best! Thank you so much for sharing this vital information. God Bless you for caring about the environment and making a definite difference in the quality of life for all of us, our wildlife and our Earth. You have absolutely made my day!

I'm sending you a hub hug ;)


Peggy Woods from Houston, Texas on March 10, 2013:

I also tweeted this and sent it to FB where it has already been shared by one of my hopefully this message will get out there so that more people stop purchasing these lethal products. Again...thanks for writing this!

Connie Smith (author) from Southern Tier New York State on March 09, 2013:

Thank you so much StephanieB! I'm glad you found it useful, and I really appreciate your supportive comments. Thanks very much for stopping by :)


Stephanie Bradberry from New Jersey on March 09, 2013:

This is a very detailed article. It is very informative and helpful. Well done.

Connie Smith (author) from Southern Tier New York State on March 09, 2013:

Hi torrilynn! I am very pleased you read this article. The more we know about the things that are potentially harmful to our environment and us, the better we can make informed choices in the products we buy. Unfortunately, big business has a way of working around being completely honest sometimes.

Thanks so much for the vote and for your comments. They are very much appreciated!


Connie Smith (author) from Southern Tier New York State on March 09, 2013:

Hi Peggy, Again I share your sentiments when it comes to killing animals. I truly believe each one has its place in this universe, and serves a purpose. There are always either natural or non-toxic alternatives that are harmless to all. I understand the problems occurring in the big cities due to people living in such close proximity. But even NYC has acknowledged that these rat and mouse baits are too risky to use. That tells me that the major problem is not the infestation, but the money that can be made by big, greedy, uncaring companies.

I am so thankful that you are sharing this with your followers. You're right--it is super important that people know the true nature of the products they use.

Recently I read that Reckitt Benckiser has enlisted a former congressman to aid in their efforts to drag out this issue in court as long as possible. In the meantime they continue to make millions of dollars while our children, pets and natural predators remain in peril.

Your excellent support is very much appreciated. Thank you for your votes and shares!


torrilynn on March 09, 2013:

Hi grandmapearl,

thanks for the interesting story that you have written here

I've learned new things about rat poisoning that I did not know before

thanks again and Voted up

Peggy Woods from Houston, Texas on March 09, 2013:

I would rather not kill any living thing if at all possible. To read the lengths we went to get rid of squirrels in our attic, read my hub Two Funny Cute and Short Stories about Squirrels if you are interested. Voting this hub UUI and will share far and wide. This is so important to know because these chemicals are dangerous with long lasting effects. So glad that you wrote this!

Connie Smith (author) from Southern Tier New York State on February 14, 2013:

tsadjatko, What a terrific story. If the Vitamin K improved the health of that barn owl, then it had most definitely been poisoned. Thank you for caring enough to research and help that animal. I'm glad you happened to look out that window. Sadly, this happens way too often to our wonderful birds of prey, as well as our 4-legged rodent eaters.

Thank you so much for sharing your heartwarming story. I wish you well, and I thank you.


Connie Smith (author) from Southern Tier New York State on February 14, 2013:

Hi Deb, you are so right about the water. All these horrible poisons are doing a number on us all. It seems like the powers that be usually come up with a sledgehammer, when a flyswatter would do better!

Thanks for the visit and the comments. It's always good to see you!

Connie Smith (author) from Southern Tier New York State on February 14, 2013:

Dear Eddy, Happy Valentine's Day to you as well, my friend. I wish you much love from my woodland in New York State. Thank you as always for your very supportive comments. They mean the world to me!

Have a wonderful day,


Eiddwen from Wales on February 14, 2013:

So interesting and useful pearl ;your obvious hard work has certainly paid off and here's to many more to share on here.

A very Happy valentine's day for you my dear friend. Lots of love from my little corner of Wales.



Deb Hirt from Stillwater, OK on February 13, 2013:

I like the peppermint oil approach. For decades, birds have been killed due to assorted rat poisons. Think of the poison that gets into our groundwater, too...

The Logician from then to now on on February 13, 2013:

Terrific exhaustive article! One winter day Iwas looking out my kitchen window at the snow covered ground as the snow was piling up and noticed in a big oak tree a large bird flapping it's wings, then hanging upside down from the branch and consequently falling to the ground. I ran out to find a Great Horned Owl laying on the snow, alive but so weak he hardly moved. I brought him in the house and put him in a cardboard box. An examination revealed no injuries bu he lay there incapacitated. I suspected that either he was dying of malnutrition or poison. He had plenty of meat on him so I ruled out hunger and proceeded to research mouse poison. I discovered that the poison keeps the mouse's blood from coagulating and they die from internal bleeding. I also discovered a possible antedote (if he had eaten a mouse that had been poisoned and was easy prey) would be to give the animal vitamin K so I ran to walmart and purchased a supplement containing vitamin K and proceeded to administer it orally with an eye dropper and water in case he was dehydrated. Within hours the bird gained strength and could stand up. He grew stronger with each passing day and seemed to know me as he was so tame he'd perch on my hand (with a glove of course) exhibiting no fear as I walked around with him. I fixed a perch for him outside in a coverd kennel and fed him daily a diet of mice and chicken hearts and gizzards. After he showed he was back to normal activity for three weeks one night I left the kennel open and he returned to the wild on his own. I can't be sure if poison was the cause, maybe he was someone's pet and they released him at the end of the summer and he wasn't adept at being on his own in winter...I don't know but I suspect it was the poison as he seemed very healthy and had good weight..

Connie Smith (author) from Southern Tier New York State on February 12, 2013:

Hi Audrey, I'm so glad you enjoyed this article, and I appreciate your supportive comment. We definitely need to help restore the natural balance in our environment. Thanks for stopping by!


Connie Smith (author) from Southern Tier New York State on February 12, 2013:

Thank you prettynutjob! I'm glad you stopped using the baits, especially since the critters left some of it behind in your silverware drawer! That is disgusting, and downright dangerous for you, too. The alternatives are much safer for all of us. I really appreciated the votes and share, and your supportive comments!


Connie Smith (author) from Southern Tier New York State on February 12, 2013:

Hi Carol, so glad you stopped by and left such a great comment. Peppermint oil works very well for me. In fact, I grow a lot of peppermint out back and harvest it in the fall. I just love the smell of it, too. Thank you so much for the vote, share and pin; always very much appreciated.


Connie Smith (author) from Southern Tier New York State on February 12, 2013:

Billy, so glad you stopped by. I'm always pleased to see you and read your great comments. I'm with you--live and let live. That is, unless they start scrambling around in the attic and keep me awake at night! Then it's time to grab the peppermint oil and some cotton balls; or the humane trap! Yeah, finding a mouse in your bed would be a bummer for sure. LOL ;)


Connie Smith (author) from Southern Tier New York State on February 12, 2013:

Lady Guinevere, I couldn't have said it better myself! I remember that old commercial about 'how it's not nice to fool with Mother Nature'. Ain't it the truth. We'd all be a lot better off if we just think about our actions and their possible consequences before acting, wouldn't we?!

Thanks for your supportive comments and the share. They are very much appreciated.


Audrey Howitt from California on February 12, 2013:

This is an excellent article on this subject. Thank you!

Mary from From the land of Chocolate Chips,and all other things sweet. on February 12, 2013:

Great informative hub, we used to use the pellets. We stopped using them because we started spotting bits of uneaten pellets in our silverware drawer. Yuck!!! Great hub voted up, awesome and shared.

carol stanley from Arizona on February 12, 2013:

I like your ideas..and after having an infestation of mice when we moved backto Arizona on a permanent basis..I detest those little guys. I had the house sanitized after they were gone. I will remember the peppermint if I ever see those rodents again. Thanks for a great hub. Voting up, pinning and sharing and all that

Bill Holland from Olympia, WA on February 12, 2013:

Great research and facts, Pearl. I have just reached a point where I live and let live. These little buggers aren't going anywhere despite my best efforts. :) As long as they stay out of my bed I'm happy.

Debra Allen from West Virginia on February 12, 2013:

When we fool with Nature it always comes back to "bite" us in the behind later. A great hub with lots of useful information. Am sharing this one too.