How Does Rat Poison Affect People?

Various rat poisons used to control rodents have potent effects on people if ingested. Many rat poisons contain anticoagulants, which are medications that interfere with blood clotting. As rats have become resistant to poisons, new superwarfarins that are more toxic to both rats and people have been marketed. Several other rat poisons are used by government agencies or trained personnel only. The University of Florida reports that in the U.S. in 1996, more than 13,000 people ingested rat poison—96 percent unintentionally. Full effects of taking rat poison may not occur for up to two weeks after ingestion, "The New York Times" warns.


Anticoagulants such as warfarin in rat poisons normally cause bleeding several days after ingestion. Visible bleeding may occur from the nose and gums and causes large bruises all over the body. Visible blood may be seen in the urine and stools and may also be vomited. Internal bleeding can cause pallor and low blood pressure. Bleeding can deplete red blood cells, causing anemia. Bleeding into the brain can cause confusion, agitation or lethargy.

Cardiopulmonary Effects

Zinc phosphide, still available in retail stores in the United States, according to the National Pesticide Information Center, can cause:

  • tightness in the chest
  • difficulty breathing
  • cough 1

Pulmonary edema, or fluid in the lungs, may develop. Cardiomyopathy, weakening of the heart muscles and irregular heartbeat can also occur with zinc phosphide poisoning.

Liver Failure

Ingestion of zinc phosphide can cause liver damage, with jaundice, a yellow discoloration of the skin and whites of the eyes and coma from encephalopathy, brain damage related to toxin buildup in the brain in liver failure.


Strychnine, a poison approved for used only by trained personnel, can cause severe convulsions, usually within 15 to 20 minutes after ingestion, the NPIC warns. Convulsions can also occur after zinc phosphide poisoning.


If internal bleeding continues, shock develops from decreased blood volume, or hypovolemia. Coma and death can follow. Shock can also occur in zinc phosphide poisoning.