Poison

Poisons, toxins, and venoms are all poisonous, intoxicating substances - powders, liquids, and gases - that can be used by shinobi in combat. Poisons come with a variety of effects, ranging from body weakness to paralysis and/or death.

Canon Types
There are different types of poison, some more effective than others:
 * Tsunade has been noted by Jiraiya to be the only person capable of poisoning a ninja without them knowing, as she managed to spike his sake with an odourless, colourless poison that left him unable to properly control his chakra.
 * Ino Yamanaka has been shown to at least have knowledge of poisonous plants, seen early when she threw poisonous plants into Ami's mouth. She also makes heavy use of wolf's bane in the video games.
 * Sasori had developed such a poison that even if a small amount is introduced into the bloodstream, the affected person will die within three days while also being painfully paralysed for the duration. According to Sakura, this poison is refined with heavy metals which gets into the muscles and destroys the cells. The antidote for this poison is extremely complex - so much so that no one in Sunagakure was capable of creating it.
 * Orochimaru's true form's blood is poisonous, and evaporates upon contact with air, paralysing anyone who breathes it in. Its potency is such that even Sasuke Uchiha, who has gained an immunity to most poison, was affected.
 * One of the poisons taught to Sakura by Shizune is able to be entrenched in kunai and has a delayed effect, as Naruto was cut with it but collapsed some time afterwards.
 * Sakura also uses smoke bombs that contain a strong knock-out gas that can even render ninja like Sai, Lee, and Kiba unconscious in moments.
 * Kabuto Yakushi has developed a poison which is specifically designed to suppress the Wood Release kekkei genkai.
 * Hanzō, in his youth, transplanted the poison sac of a black salamander in his village. He was able to poison the environment just from breathing. He also imbued his kusarigama's blade with poison.

There are animals which can produce different types of poisons:
 * Snakes, summoned by Orochimaru, sometimes are able to secrete venom from their fangs.
 * Ibuse can release a large amount of Poison Mist that almost instantly paralyses anyone that breathes it in.

There are also several species of insects that use poison in their attacks. Other insects, such as the kikaichū, can be cultivated for the purpose of neutralising poisons and toxins used on the bug-user's allies:
 * Rinkaichū - Torune Aburame and Shikuro Aburame can subsequently infect the opponent with these bugs, causing an excruciatingly painful and likely fatal injury unless the afflicted area is swiftly removed. However, there is in fact an antidote, but only Shikuro Aburame knows how to make such an antidote.
 * Kochū - Used by Yōji Aburame, these insects can infect targets with a poison that will paralyse the victim and kill them shortly afterwards. As the poison disappears upon death, it can't be found during autopsies, making these insects perfect for assassinations, as they are as imperceptible as mosquitoes yet as deadly as scorpions.

Non-Canon Types

 * Aniki, the leader of the Moya Triad, had tried several types of poison against Kakashi, which were to make him hiccup, laugh, and cry uncontrollably until he died from it.
 * Bees - The Kamizuru clan of Iwagakure has ninja bees that can inject venom into a enemy through their stingers.
 * The Wandering Ninja Clan used an odourless type of poison powder that slows down the victims' senses and reaction time.
 * Fuen used a poisoned powder which caused those who inhaled it to experience controlled hallucinations.
 * The Sea Route of Silence Gang used the Moulding Mushroom to poison their victims and make them easy prey.

Usage
Most poison users use poison on their weapons through various means. Sakura, for example, after learning from Shizune coats her kunai with poison so that if she is able to cut the target, they are instantly injected with the toxic substance. Puppet-users, such as Kankurō and Sasori, prefer to put poison inside their puppets so that they inject via hidden bladed weapons. Sasori, similarly to Sakura, puts poison that is clearly noticeable on the blades of his puppet, the Third Kazekage, as well as in his Iron Sand, which is far less noticeable.

Poison may be used in other forms, not only as a liquid substance. It can be used in a mist form, as demonstrated by Shizune with her Poison Mist technique. Inhaling the slightest bit of poison can prove fatal, as seen when Sasori trapped Sakura in two consecutive waves of his poison mist. Such vapours can also be used for paralysing effects, as Ibuse demonstrated.

Combating Poisons
Certain characters have encountered poisons throughout their careers as ninja. Those skilled in the fields of chemistry and biology are capable of producing antidotes to the poisons. Tsunade, during the Second Shinobi World War, was able to produce antidotes to every one of Chiyo's poisons, much to the latter's resentment. During the mission to rescue Gaara, Sakura Haruno demonstrated the skill to not only extract and analyse Sasori's poison swiftly, but also produced an antidote to counter it, something Chiyo could not do.

Apart from using antidotes to poisons, a ninja can also work to build-up a tolerance to certain poisons by gradually exposing oneself to non-lethal amounts of those poisons. Orochimaru, in the effort to make Sasuke Uchiha into the perfect vessel for his Living Corpse Reincarnation technique, made it a point to make Sasuke immune to most poisons, such as the one that Shizune taught to Sakura Haruno in order to use on her kunai. Anko was seemingly put under the same regime during her time with Orochimaru. Mifune has been shown to have built up an immunity to both Hanzō and Ibuse's poison.

When Naruto was poisoned by The Demon Brothers with their poisoned gauntlets, Kakashi told him that they could treat his wound by cutting him and letting the blood flush out the poison. This method of treating poisoned wounds has not been mentioned since and is presumably only viable in certain situations.

Trivia

 * Tsunade likened the Wind Release: Rasenshuriken to poison due to the cellular damage it inflicts on the user if used at melee range, potentially leading the user to be crippled as backlash.
 * After Naruto attacked Sakura in his four-tailed form, she briefly fell ill as a result of some chakra from the Nine-Tailed Demon Fox entering her body through her wounds. This caused Yamato to compare the Nine-Tails chakra to a poison. Naruto himself was also negatively affected, with the caustic chakra burning away his skin.