Poisons, toxins and venoms are all poisonous, intoxicating substances - powders, liquids and gases - that can be used by ninja in combat. Poisons come with a variety of effects from body weakness, paralysis or death.
There are different types of poison, some more effective than others.
- Snakes summoned by Orochimaru and others, sometimes are able to secrete venom from their fangs.
- 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.
- Kabuto Yakushi has developed a poison which is specifically designed to suppress the Wood Release kekkei genkai.
- 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.
- The Three Wandering Ninja used an odourless type of poison powder that slows down the victims' senses and reaction time.
- Fuen used a poison that is thin and tiny enough to be taken into the air, and cause those who inhale it to see whatever she wants.
- 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.
- Ibuse can release a large amount of Poison Mist that almost instantly paralyses anyone that breathes it in.
- 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.
- Misaki Akibana uses poison that is derived from certain flowers, and she has stated it to be so toxic that it is comparable to that of a Black Mamba snake.
- Yū, being a expert in sleeping and psychological conditions, has a vast knowledge of sleeping poisons and can determine how long the victim will sleep for. Yū has also developed a sleep deprivation poison but, wears off after two days. She is currently working on a poison that can induce eternal sleep.
There are several species of insects that use poison in their attacks. While other insects, such as the Kikaichū, can be cultivated for the purpose of neutralising poisons and toxins used on the bug-user's allies.
- Bees - The Kamizuru clan of Iwagakure has ninja bees that can inject venom into a enemy through their stingers.
- Nano-sized, venomous insects - Torune 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.
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 Chiyo, 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. Raiku Uchiha also showcased the ability to paralyze anyone who makes external bodily contact with his Poison mist. He can also render organs within the body useless by infecting the bloodstream with the poison, which may prove fatal to the victim.