Poison is often used to kill rats, though it is not recommended by exterminators and is not allowed in some states. This is because it can not only kill rats but also pets and humans if given in the right doses, or at least make them very sick over a longer period of time. The long-term effects of rat poison can be permanently damaging.
There is a toxin used in certain incredibly toxic rat poisons called cholecalciferol that is also known as vitamin D3. These rodenticides, which are vitamin-D3-based, are some of the most dangerous out there, as it causes an excess of calcium in the bloodstream of all animals who ingest it, which will quickly cause kidney failure. This damage, once the poison is ingested, is almost irreparable and will lead to long-term organ failure within the body. There is no reason to have this type of poison in a home or garage where adults, children or pets can accidentally poison themselves with it.
Weakness and Internal Bleeding
Most rat poisons that are sold on the market contain long-acting anticoagulants (LAACs), which keep the body from clotting normally and causes internal bleeding. If this is ingested in a large enough amount by a larger animal than a rat, ranging from a small pet to a human being, the effects will come on in the next week and get progressively worse. Symptoms will include large and small lumps under the skin, bloody urine and bloody vomiting, among other signs of sickness. Fortunately, if caught and treated soon enough, this will not cause any long-lasting permanent damage. Most vets and hospitals have vitamin K1 on hand just in case this type of poison is ingested. Blood transfusions may also be required.
Heart and Lung Complications
Some rat poisons or lawn and rodent poisons contain large amounts of phosphides, which come in a gummy worm-type form that the rodents will eat. This results in phosphide gas in the stomach, which causes those who ingest it to bloat and vomit profusely. While humans rarely ingest this type of poison, pets are drawn to it as much as rats. An added complication comes when a dog or cat vomits up the poison, a gas will rise off of it that still contains the poison, which can then be inhaled by humans and poison them. This is another dangerous poison to have around your house. Use rat traps.