Rat poisons are a category of pest control chemicals intended to kill rats.

Single feed baits are chemicals sufficiently dangerous that the first dose is sufficient to kill.

Rats and certain other vermin are difficult to kill with poisons because their feeding habits reflect their place as scavengers. They will eat a small bit of something and wait, and if they don't get sick, they continue. A good rat poison must be tasteless and odorless in lethal concentrations, and have a delayed effect.

Anticoagulants

Fatal internal bleeding is caused by overdose of anticoagulant drugs such as:

• brodifacoum
• bromadiolone
• chlorophacinone
• diphacinone
• warfarin

Coagulant drugs or Vitamin K1 have been suggested as possible antidotes for pets accidentially exposed to anticoagulant poisons. In addition, since some of these poisons act by inhibiting liver enzymes, a blood transfusion (with the enzymes in question's products present) can save a person who inadvertently takes them, an advantage over some older poisons.

Poisonous chemicals

Other chemical poisons include:

• barium (a toxic heavy metal)
• barium carbonate
• bromethalin (which affects the nervous system, no antidote)
• strychnine
• tetramine
• thallium (a toxic metal)

Alternatives

Mechanical rat traps are one possible alternative to poisons; another alternative is to buy a cat. Both of these methods have a disadvantage of being comparatively messy, a particular problem when the building with a rat problem is to be uninhabited for some months. Anticoagulants have the advantage that their first effect is dehydration from blood loss, causing the unfortunate rodent to leave the building in search of water.