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What is the difference between “venom” and “poison”? Both in usage and in meaning.

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  • Related: Is a snake's venom poisonous (or venomous)?
    – herisson
    Commented Sep 20, 2017 at 20:04
  • See also here, here, and here for other SE discussions of the poison/venom/toxin distinction.
    – lly
    Commented May 10, 2023 at 2:26
  • Svick, if you ever stop by SE any more, consider moving your tick from Jay's actually incorrect answer to DracoHandsome's far better one to move it up the page into greater visibility.
    – lly
    Commented May 10, 2023 at 3:10

8 Answers 8

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Poison is contextual and can be an artificial or natural material — different materials can be poisons to different organisms in different doses and/or when misused. Further, poison usually denotes potential lethality.

Venom is a material created and used by an organism to aid in defense and/or hunting. Venoms are not necessarily fatal — many stun, sting, or disable. Venom is venom regardless of context, and can also be poison in some contexts.

Both words are used heavily in metaphor. Poison is often used to describe something that corrupts, destroys, or has the potential to do so, usually over time — an eventuality. Venom is often used to describe harsh speech or hurtful aggressiveness.

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    @Scott Don't remind me.
    – Jay
    Commented Jan 13, 2011 at 19:29
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    And Venom is a comic book character.
    – Tester101
    Commented Jan 14, 2011 at 16:37
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    @TimLymington: No - vipers are venomous snakes. "Poisonous snakes" is a common term, but incorrect.
    – Misha R
    Commented Jul 3, 2015 at 23:08
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    @Misha: that is not the way it works in English. If poisonous snakes is the usual term, and a dictionary dislikes it on impeccable logical grounds, it is the dictionary that is incorrect. Commented Jul 3, 2015 at 23:14
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    @TimLymington: Dictionaries often provide colloquial use of words in addition to their correct use. Colloquial uses are numerous; I assumed that the original question was asking about the correct definition of the two words. You are not likely to find many professional writers or herpetologists who call vipers "poisonous." Here is a link that explains the difference, at least as it applies to animals: io9.com/…
    – Misha R
    Commented Jul 3, 2015 at 23:39
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Venom is a toxin that is harmful only when it enters the bloodstream, produced by animals of various species.

Poison is a toxin that is harmful when ingested (and, in more general terms, however it gets into the system). It is also a catch-all term for any harmful substance.

Thus there are many venomous snakes, but very few poisonous ones, i.e. ones you would have to eat for them to harm you.

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    + A notable distinction, frequently overlooked in common usage.
    – user597
    Commented Jan 13, 2011 at 18:43
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    And the black widow spider is both venomous and poisonous to humans. It is not healthy if one bites you, nor is it healthy for you to eat one. Commented Jan 14, 2011 at 23:27
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    "Venom is a toxin that is harmful only when it enters the bloodstream". Tell that to the Spitting Cobra. Commented Jul 4, 2015 at 1:06
  • @WhatRoughBeast Yeah, it's completely wrong as DracoHandsome points out below. Consider upvoting 'em to help get the better answer higher up the page.
    – lly
    Commented May 10, 2023 at 3:08
  • @thursdaysgeek - have you got a source for that? Frankly I doubt that anyone has studied the toxicity of black widow venom when ingested, but I could be wrong. Commented May 12, 2023 at 2:22
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Venom, poison, and to a lesser extent toxin are informally used interchangeably, referring to all substances that are harmful to living things. Below I will list what is my understanding of their technical differences; but as English is a living and very lax language, and as the words are used in multiple separate scientific fields, I'm sure there is some argument over the matter. Therefore, what I or anyone else tells you about their definitions isn't set in stone, so to speak.

A toxin is any inanimate substance that has an adverse interaction with an individual's biological processes, i.e. not a bacterial or other disease. This is distinct from a substance that damages anything it touches like a corrosive substance, because a toxin only works by exploiting specific biological processes. That is to say, what is toxic to a human being may not be toxic to a bird because their biological processes are different, whereas a corrosive substance is more or less equally damaging to most any creature it touches.

A poison is a toxin that can be absorbed through body tissue. Poisons are thus dangerous to touch or swallow. There are many animals partially or wholly coated in poisons such as dart frogs or even shrews, but snakes are not among them. Poisons also don't need to belong to animals or plants; certain chemical elements such as arsenic, lead, or mercury are poisons usually found outside of any living body.

A venom is a toxin that is not absorbed through the skin or mucous membranes, requiring it to be injected intentionally, such as through snake fangs or insect stingers. This necessarily means that venoms are only found produced within animals and plants. The two kinds of venom are hemotoxins which damage red blood cells and neurotoxins which damage nervous tissue. Presuming there are no cuts or other breaks in the skin or mucous membranes, venoms are completely safe to touch or swallow, but be warned that many people have tiny cuts they aren't aware of, and it's good practice never to touch venom or any toxin without protective equipment anyway.

As venoms are always biologically produced substances, they contain proteins, and so it's possible to have allergies to otherwise mild venoms such as bee stings. Theoretically, you could be allergic to biological poisons such as dart frogs, but it's not possible to have an allergy to a non-biological toxin such as arsenic.

Snakes especially are often referred to as poisonous, but that's usually incorrect - poisonous would mean they were toxic to touch or eat. Many snakes are venomous as they bear and inject venom. There are no snakes who produce their own poison, but the Japanese grass snake and the common garter snake include animals in their diets who are harmless to them but toxic to humans and can pass poisons to humans this way.

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  • By far the best answer to any of these related questions. Hopefully more people will be able to see this and upvote.
    – lly
    Commented May 10, 2023 at 3:09
  • If you ever stop by, it would benefit from some of the figurative senses given the way OP asked their question but at least you nailed the primary senses well.
    – lly
    Commented May 10, 2023 at 3:25
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Venom is contained by a living organism, and it is often used as an offensive/defensive measure to ensure survival. Venom is often poisonous to the intended target.

Poison is an item that is harmful or dangerous to the person/thing to which it refers.

Arsenic is poisonous to humans. Cobra venom is also poisonous to humans and other animals. The venom of a "Daddy Long Legs" spider is not considered to be toxic to humans, however.

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Venom is used to refer to the poisonous substances that animals like snakes and scorpions produce.

Poison is used to refer to substances that could harm or even kill somebody through its chemical action.

To illustrate the difference, consider this article: Poison, not snake, killed Cleopatra, scholar says

The article says that Cleopatra may have "died from drinking a mixture of poisons and not from a snake bite." The snake bite would release venom. But Cleopatra drank something to kill herself - that's poison.

This other article explains the same as: Cleopatra Died From Poison. She used hemlock, not snake's venom, says historian

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I have copied here a clear distinction between these terms as provided in reference dictionaries.

Poison, toxin, venom are terms for any substance that injures the health or destroys life when absorbed into the system, especially of a higher animal.

Poison is the general word: a poison for insects.

A toxin is a poison produced by an organism; it is especially used in medicine in reference to disease-causing bacterial secretions: A toxin produces diphtheria.

Venom is especially used of the poisons secreted by certain animals, usually injected by bite or sting: the venom of a snake.

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  • The OED disagrees: Poison and toxin are synonyms although toxins can particularly intend harmful substances produced by microorganisms; venoms are particularly injected, not secreted. All of those contradict the current technical jargon in the field; see DracoHandsome's answer above.
    – lly
    Commented May 10, 2023 at 3:27
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You have some good definitions, but I will add a bit of usage.

When someone has been struck down by venom—the bite of a venomous animal, or venom on a blade—they have been poisoned.

When someone has ingested something poisonous they have been poisoned.

Although technically incorrect, people often talk about snakes being poisonous, by which they mean venomous.

Venom is a word that is less commonly used now.

In that respect, in day-to-day usage you can get away with using "poison" when it might be more technically accurate to use "toxin."

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    You generally use poison on a blade, not venom. The venom example here would be a stinger or barb. It's not technically incorrect: when people talk about snakes being poisonous, they mean they have a poisonous substance. When scientists object, they're trying to restrict venomous and poisonous to solely describe the method of entry of the poisonous substance. It's just talking past each other using different categorization, not one being technically right or wrong.
    – lly
    Commented May 10, 2023 at 3:31
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The word poison is more frequent and more general

First of all, the word poison is more frequent: the Corpus of Contemporary American English (CoCA) reports a frequency of 11664, vs. only 2696 for venom.

The first, literal definition of poison given by the Oxford English Dictionary is as follows:

Material that causes illness or death when introduced into or absorbed by a living organism, esp. when able to kill by rapid action and when taken in small quantity

So "poison" is a broad, general term that can refer to all kinds of substances that can cause harm to living beings.

But some speakers make additional restrictions, discussed further below, in the use of the word "poison"—at least, in certain technical contexts.

Venom usually means a kind of toxin produced by an animal

The Oxford English Dictionary provides the following more specific definition for the word venom:

The poisonous fluid normally secreted by certain snakes and other animals and used by them in attacking other living creatures.

It also lists a second definition as a synonym of "poison", but suggests this is "Now rare".

As far as technical use goes, the first sentence of the Wikipedia article on venom says

Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action.

Pretty similar. Based on the above, it seems reasonable to say that a substance that is harmful but is not produced by an animal would normally not be called a "venom", but rather a "poison", although "venom" might be possible in poetic contexts or for some literary purpose like variation in word choice.

Whether venom is or isn't a subset of poison depends on if you are using the words in a "technical" sense

The more debated question is when to call a substance produced by animals "poison" vs. "venom".

The general definition of "poison" is broad enough to encompass venom.

I think that in practice, "poison" and "poisonous" are not infrequently used to refer to venom and venomous creatures. This is demonstrated to some extent by the CoCA frequencies for "venomous snakes" (71) vs. "poisonous snakes" (153). Looking through the results suggests that few if any of the uses of "poisonous snakes" are meant to specify that the snake is harmful to touch or eat. Even for academic sources, "poisonous snakes" is more frequent at 12 vs. 5, suggesting that the broad use of "poison(ous)" has currency even in edited texts written by educated speakers.

A more restrictive definition of "poison" that excludes venom can be found in the technical usage of some specialized fields such as biology or medicine, but I would say that it isn't adhered to in common usage.

E.g. the Wikipedia article on poison cites the following article, "Poison vs. Venom" from the Australian Academy of Science's website which draws the distinction in the following way:

Poison is a toxin that gets into the body via swallowing, inhaling or absorption through the skin. [...] 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.

However, the article starts with an acknowledgement that "The terms are often used interchangeably".

Looking up the example of the spitting cobra mentioned in a comment by WhatRoughBeast caused me to learn that a third term, "toxungen", was coined in 2013 to refer to toxic biological secretions that are "delivered to the body surface without an accompanying wound".* So if you're writing for a technical audience and follow this proposed terminological scheme, you might make a three-way distinction between poisons, venoms, and toxungens. But there is no binding obligation to observe either this trichotomy or the poison-venom dichotomy in non-technical writing: it's a matter of opinion whether it's advisable or pointless to try to stick to the technical definitions of these words in non-technical contexts.


*"Poisons, toxungens, and venoms: redefining and classifying toxic biological secretions and the organisms that employ them", Nelsen et al., Biol Rev Camb Philos Soc. 2014 May;89(2):450-65. doi: 10.1111/brv.12062. Epub 2013 Sep 17. PMID: 24102715.

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