Image adapted from: H. Krisp; CC BY 3.0

What's the difference?

Poison vs. Venom

The terms are often used interchangeably, but ‘venom’ and ‘poison’ are not the same thing. True, they’re both a toxic substance that can potentially harm or kill you, but the main difference lies in the way they are delivered to the unfortunate victim.

Poison is a toxin that gets into the body via swallowing, inhaling or absorption through the skin. Poisonous animals tend to be more passive-aggressive—they often won’t actively attack their prey, but release their toxins as a result of being eaten, touched or disturbed. A cane toad, which secretes toxins from glands on each shoulder, is a poisonous animal. It has to be ingested or licked to cause harm. Poison ivy is an example of a poisonous plant—touching it can result in an itchy and sometimes painful rash.

Venom is a specialised type of poison that has evolved for a specific purpose. It is actively injected via a bite or sting. Because venom has a mixture of small and large molecules, it needs a wound to be able to enter the body, and to be effective must find its way into the bloodstream. For this reason, venomous animals are more active in defending themselves. A taipan, which injects venom through syringe-like teeth, is a venomous animal. So are jellyfish, which inject venom into skin using venom-filled harpoon-like structures that shoot out from cells along their tentacles when touched.

Occasionally an animal can be both venomous and poisonous. The blue-ringed octopus, for example, is venomous when it bites with its beak but it is poisonous if it is swallowed. This is because it has a myriad of toxins in it, with the most potent (tetrodotoxin) able to be absorbed due to its very small size.

Both poison and venom are designed to be effective if delivered in the correct way. But what would happen if you drank venom (rather than having it injected)? While there have not been many people willing to submit to this experiment, it is theoretically possible to swallow venom and not notice any effects (unless of course you had cuts in your mouth, in which case it could enter your bloodstream). This is because the acids in your stomach would break down the venom like any other protein before it could reach your bloodstream—at least, that's the theory.

Regardless of whether it’s ingested or injected, the safest option is to be aware of potential poisonous and venomous creatures in your area, and try and avoid them.

This article has been reviewed by the following experts: Associate Professor Bryan Fry School of Biological Sciences, University of Queensland; Dr Timothy Jackson Australian Venom Research Unit, University of Melbourne