Am I right in believing that venomous and poisonous are not interchangeable?

Venomous death would include being bitten by something and then you would die from the animal's venom. From Merriam-Webster:

venom noun ven·​om | \ ˈve-nəm \ 1 : a toxic substance produced by some animals (such as snakes, scorpions, or bees) that is injected into prey or an enemy chiefly by biting or stinging and has an injurious or lethal effect ; broadly : a substance that is poisonous 2 : a spiteful malicious feeling or state of mind : extreme ill will : MALEVOLENCE

Poisonous death would include you biting into something and then you would die from being poisoned by the animal. From Merriam-Webster:

poison noun poi·​son | \ ˈpȯi-zᵊn \ 1 a : a substance that through its chemical action usually kills, injures, or impairs an organism b (1) : something destructive or harmful (2) : an object of aversion or abhorrence 2 : a substance that inhibits the activity of another substance or the course of a reaction or process <a catalyst poison>

The toxicity levels are a general gradient which would set to determine the level of toxicity within the poison or venom. From Merriam-Webster:

toxicity noun tox·​ic·​i·​ty | \ täk-ˈsi-sə-tē \ plural toxicities : the quality or state of being toxic: such as a : the quality, state, or relative degree of being poisonous <measuring the toxicity level of the soil> <The toxicity of some chemical agents degrades significantly over time, so it is unclear how lethal the stockpiles are. — David S. Cloud> ... b : an extremely harsh, malicious, or harmful quality <In the past few days, I've tuned in to C-SPAN to watch a number of the televised Senate debates, which illustrate all too vividly the toxicity of an uncivil tongue. — Connie Schultz>

This would be the correct scientific lexicon within their definitions.

It’s all down to the method of delivery. Venoms must be injected to be effective, whereas poisons can come into contact with skin, or be inhaled, eaten or touched. So the puffer fish is poisonous if you eat the wrong part, because its liver contains tetrodotoxin, but its bite contains no toxins. sciencefocus.com/nature/… BBC Science focus makes clear the difference between 'poison and venom within snakes' The blue-ringed octopus, however, can inject the same tetrodotoxin with its bite, so it is venomous. There is only one species of snake that is both venomous and poisonous. The Asian tiger snake has one toxin for its venomous bite, but it also stores a poison in its skin that comes from the toads that it eats.

Can anyone further this assertion?

  • Please include definitions from a good dictionary. You'll have to explain how this isn't primarily opinion based, since such questions are off-topic. See the help center. Commented Sep 10, 2019 at 17:05
  • 1
    I feel like you've answered your question already. The only nuance is that most non-specialist people might make the reasonable mistake to call a venomous snake poisonous, but would not likely call a poisonous berry venomous. The technical definitions spell out what is correct, but in non-rigorous speech 'poisonous' is probably more often used than 'venomous' checking NGrams as we speak_
    – Mitch
    Commented Sep 10, 2019 at 17:18
  • I would see this as a reflection of the media's use of these words interchangeably when discussing the attacks by venomous creatures, the ingestion of poisons and how they relate toxicity to the two causes confusion. Scientifically and linguistically there are differences in the words themselves and the development of the words. It's not an opinion but a clarification of the correct terminology.
    – Sam Monk
    Commented Sep 10, 2019 at 17:19
  • ...and Google NGrams endeavors to please: poisonous snake' is twice as common as venomous snake. Logically I suppose if you ate an entire venomous snake, one would consider that situation poisonous. But in non-technical terms, 'poisonous snake' is what people usually use when the snake is venomous.
    – Mitch
    Commented Sep 10, 2019 at 17:21
  • 1
    @Sam edit them into the question. Comments aren't always seen, and can be easily deleted by moderators. Commented Sep 10, 2019 at 17:26

2 Answers 2


You ask whether venomous and poisonous are (or are not) interchangeable.

As you and the many people who have posted comments point out, the two words are being distinguished scientifically: venom is injected into the bloodstream; poison is ingested, inhaled, or absorbed.

However, there are centuries of use, including modern use, where the two words are used, if not interchangeably, to mean the same thing.

Consider the OED's first definition of venom as a noun:

a. The poisonous fluid normally secreted by certain snakes and other animals and used by them in attacking other living creatures.The venom of snakes is secreted in a poison gland communicating with the fangs, through which it is ejected in the act of striking.

The OED's third definition of venomous as an adjective is:

a. Of animals, esp. snakes, or their parts: Secreting venom; having the power or property of communicating venom by means of bites or stings; inflicting or capable of inflicting poisonous wounds in this way.Formerly in general literary use, now chiefly restricted to certain species of poisonous snakes.

The OED's first definition of poisonous is:

  1. Containing, or of the nature of, poison; having the properties of a poison; venomous.

So the OED itself is using each word to, in part, define the other. Both have, as the OED points out in many definitions and quotations, figurative uses.

In a biology class, the professor would clearly take points off for calling a venomous snake "poisonous," but in ordinary English, this use is acceptable and standard.


A bit of additional context to Xanne's answer:

Am I right in believing that venomous and poisonous are not interchangeable?

Yes, albeit not for the usual pedantic reasons.

Toxic is 100% a synonym of poisonous, having or similar to poison, any substance that causes illness or death upon introduction to the body, etymologically derived from quack doctors' bad potions. (See mithridaticum for what Roman and medieval potions and elixirs could consist of, only slightly worse than the Chinese ones heavily favoring mercury.)

Toxin, however, is broadly synonymous with poison but can be restricted to poisons produced by microorganisms. Similarly, venom is broadly synonymous with toxin but is properly restricted to toxins produced by organisms for offensive use, chiefly snakebites but also beestings and various animals that spit or shoot venom.

In short, in common use, all venoms are poisonous, but not all poisons are venoms.

The above is per the OED. This answer from DracoHandsome to an identical question provides additional context. The current professional usage is a little different: Toxins are the catch-all term for inanimate substances harmful to a particular organism, poisons are any toxins that can be passively absorbed by a particular organism's tissues, and venoms are any toxins that must be actively injected, requiring them to be organically produced. The two main venoms are hemotoxins (poisonous once in the blood) and neurotoxins (poisonous once in contact with nerves). For what it's worth, the OED has no entry at all for hemotoxin and thinks neurotoxins are any substance toxic to parts of the nervous system.

Here, for modern jargon, all venoms and poisons are toxins, but differ from each other entirely in their method of introduction to an organism. (Theoretically, some injected venoms could be so toxic that they would also act as a passive poison but presumably people in this system are trained to think of them as entirely different based on their usual method of introduction.)

Venomous snakes produce poisons, but the snake itself—i.e., its meat—is not necessarily poisonous. Venomous snakes are called poisonous snakes because they have poison, but some biology teachers who half-understand the above will mark students down for calling them poisonous in an attempt to underline the distinction between the method of introduction.

  • It is interesting that the term "radiation poisoning" is used. I do not recall hearing "radiation toxicity" but both terms I am not happy with since the mechanism of action is very different than chemical poisoning. If you got severely sunburnt (which is to me very close to radiation poisoning, perhaps identical) you would not call it "solar toxicity" or "sun poisoning". If you were injured from boiling water, again similar to radiation in its damage I think, you would not call this "heat poisoning" or "boiling water toxicity".
    – releseabe
    Commented May 10, 2023 at 7:05
  • @releseabe My instinct would be that severe enough sunburn could absolutely be described as 'solar poisoning' and Google seems to agree. It's not terribly common relative to 'sunburn' and 'thermal poisoning' seems to mostly be about industrial processes instead of heat stroke, but it at least scratches that discomfort you had about 'radiation poisoning'.
    – lly
    Commented May 10, 2023 at 7:51
  • @releseabe Your general point stands: They may be mostly interchangeable within the OP's context but there are some extended and figurative senses where, no, they don't really overlap as neatly.
    – lly
    Commented May 10, 2023 at 7:55
  • To me, toxicity implies chemical action. Radiation poisoning may be a holdover from a time when proximity to, say, radium, caused symptoms that reminded people of chemical exposure. At some point, we definitely do not call insult to the body poisoning: if you are struck by a stone, for example. If you fall from a height, no one would seriously call this "gravity poisoning". One thing about radiation is dosage, but I still feel calling radiation damage poisoning is not really apt.
    – releseabe
    Commented May 10, 2023 at 10:33

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