Nicotine poisoning describes the symptoms of the toxic effects of nicotine following ingestion, inhalation, or skin contact. Nicotine poisoning can potentially be deadly, though serious or fatal overdoses are rare. Historically, most cases of nicotine poisoning have been the result of use of nicotine as an insecticide. More recent cases of poisoning typically appear to be in the form of Green Tobacco Sickness, or due to unintended ingestion of tobacco or tobacco products or consumption of nicotine-containing plants.Standard textbooks, databases, and safety sheets consistently state that the lethal dose of nicotine for adults is 60 mg or less (30–60 mg), but there is overwhelming data indicating that more than 0.5 g of oral nicotine is required to kill an adult.Children may become ill following ingestion of one cigarette; ingestion of more than this may cause a child to become severely ill. The nicotine in the e-liquid of an electronic cigarette can be hazardous to infants and children, through accidental ingestion or skin contact. In some cases children have become poisoned by topical medicinal creams which contain nicotine.People who harvest or cultivate tobacco may experience Green Tobacco Sickness (GTS), a type of nicotine poisoning caused by skin contact with wet tobacco leaves. This occurs most commonly in young, inexperienced tobacco harvesters who do not consume tobacco. Signs and symptoms
Nicotine poisoning tends to produce symptoms that follow a biphasic pattern.
An accidental ingestion of only 6 mg may be lethal to children.It is unlikely that a person would overdose on nicotine through smoking alone. The US Food and Drug Administration (FDA) stated in 2013: "There are no significant safety concerns associated with using more than one [over the counter] OTC [nicotine replacement therapy] NRT at the same time, or using an OTC NRT at the same time as another nicotine-containing product—including a cigarette." Ingestion of nicotine pharmaceuticals, tobacco products, or nicotine containing plants may also lead to poisoning. Smoking excessive amounts of tobacco has also led to poisoning; a case was reported where two brothers smoked 17 and 18 pipes of tobacco in succession and were both fatally poisoned. Spilling an extremely high concentration of nicotine onto the skin can result in intoxication or even death since nicotine readily passes into the bloodstream following skin contact.The recent rise in the use of electronic cigarettes, many forms of which are designed to be refilled with nicotine-containing "e-liquid" supplied in small plastic bottles, has renewed interest in nicotine overdoses, especially the possibility of young children ingesting the liquids. A 2015  Public Health England report noted an "unconfirmed newspaper report of a fatal poisoning of a two-year old child" and two published case reports of children of similar age who had recovered after ingesting e-liquid and vomiting. They also noted case reports of suicides by nicotine, where adults drank liquid containing up to 1,500 mg of nicotine.