Poison
Poisons are toxicological substances that adversely affect living tissue, with effects ranging from slight discomfort to death. They can be natural or synthetic in origin. Poisons secreted by animals were called venom. Nerve gas was a synthetic poison. 

The venom of the mugato and the alkaloids of the borgia plant were examples of natural poisons. Both were capable of killing an adult humanoid. () Artificial poisons included Felodesine chips and Veridium Six. ()

In 2083, the irradiated fallout of an asteroid contained poison when it hit the surface of Terra Nova. The Novans later spoke about the "poison rain" released to their ancestors. ()

On Dimorus, the indigenous rodent creatures used deadly poisoned darts as weapons. ()

Sevrin died when he ate a poisonous fruit on Eden. ()

In 2270, an Orion captain attempted to commit suicide by taking a poison pill, but James Kirk stopped him. ()

At the San Francisco bar, Dr. Leonard McCoy ordered Altair water. The waitress, familiar with McCoy's usual request, quipped that his order "wasn't (his) usual poison." McCoy, suffering from a mind meld, retorted uncharacteristically, "to expect one to order poison in a bar is not logical." ()

On Ligon II, the dueling weapons were coated with an alkaloid-based poison. As a result, a person could be killed instantaneously by a grazing wound. ()

In 2366, nanites caused an environmental system malfunction on the bridge the  which released toxic levels of nitrogen oxide. ()

The substance dispensed by unnamed aliens to their captives as food in 2366 was poison to the Chalnoth, such as Esoqq. ()

K'mpec, the Chancellor of the Klingon Empire, was killed with the poison Veridium Six in 2367. K'mpec stated that the surreptitious use of poison, as opposed to an assassination where the attacker showed his face, was considered a dishonorable act among Klingons. ()

Commander Benjamin Sisko was skeptical about the orange bubbling liquid he was offered while in the third shap of the Wadi game Chula and thought that it could be a drug or poison, but ultimately it was the antidote for the gas. ()

While Rom was employed by Martus Mazur at Club Martus in 2370, he suspected that Quark might have poisoned the club's food with an intestinal bug, and was scanning it to make sure it wasn't. ()

The kaylo, a fruit found on a planet in the Delta Quadrant, was extremely poisonous and could lead to death. ()

The Kazon-Nistrim used a poisoned ring with a needle to kill people. ()

Poisons were the favored method of assassination of the Flaxian Retaya. ()

Morn suffered from food poisoning in 2371. He believed it was due to a free glass of kanar he was given in Quark's. He later visited the infirmary to be treated. Quark had planned to present two glasses of the same kanar as presents to Cardassian guests visiting the station. After Jadzia Dax discovered them to be spoiled, Odo threatened to arrest Quark if he did not take the bottles and leave. ()

In 2372, when Quark sought to fulfill the terms of a contract with Brunt calling for his death, poison was one option Elim Garak suggested he could utilize. However, Quark would not willingly eat food he knew to be poisoned, and he decided he wanted his death to be sudden. Ultimately, he broke the contract. ()

The Vorta were genetically engineered to be immune to most types of poison. In 2373, Weyoun drank a glass of kanar containing enough voraxna poison to kill a dozen Cardassians. Afterward, he remarked that their physiology "comes in handy when you're a diplomat". ()

In 2374, Damar suspected Quark might have poisoned his beverage in retaliation for the Dominion arresting his brother Rom for terrorism. Quark attempted to drink Damar's beverage to prove him wrong, which convinced him that it was safe. ()

Luther Sloan once claimed that Vice Admiral Fujisaki, the Deputy Chief of Starfleet Intelligence, died of food poisoning, something the Section 31 member blamed the Romulans for. ()

Following an incident in which Seven of Nine suggested individually to Commander Chakotay and Captain Kathryn Janeway that each was involved in a conspiracy against the other, the two met in Janeway's quarters and shared coffee. Chakotay jokingly asked "You didn't poison the coffee, did you?" and Janeway replied "Not any more than I usually do". ()

In 2377, Neelix poisoned Gar with Talaxian wormroot to get him to confess that he had kidnapped The Doctor and sold him to Chellick for use on Hospital Ship 4-2. ()

When the  was shattered into 37 separate time frames, Commander Chakotay tried to convince Captain Janeway of this by offering to inject her with a hypospray containing a serum that would make her immune to the effects of changing time frames. She declined the offer, stating that for all she knew, it could be poison. He then grabbed her and held the hypospray to her neck, stating that it was poison and he'd use if the security guard that was there didn't drop his weapon. ()

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 Poison
Death