They recovered (helped by vomiting), but an ingestion apparently of about 10,000 mg was fatal, as was an injection. They commented that "Serious nicotine poisoning seems normally prevented by the fact that relatively low doses of nicotine cause nausea and vomiting, which stops users from further intake." Four adults died in the US and Europe, after intentionally ingesting liquid. Two children, one in the US in 2014 and another in Israel in 2013, died after ingesting liquid nicotine.The discrepancy between the historically stated 60-mg dose and published cases of nicotine intoxication has been noted previously (Matsushima et al. 1995; Metzler et al. 2005). Nonetheless, this value is still widely accepted over the 500mg figure as the basis for safety regulations of tobacco and other nicotine-containing products (such as the EU wide TPD, set at a maximum of 20mg. Pathophysiology
The symptoms of nicotine poisoning are caused by effects at nicotinic cholinergic receptors. Nicotine is an agonist at nicotinic acetylcholine receptor which are present in the central and autonomic nervous systems, and the neuromuscular junction. At low doses nicotine causes stimulatory effects on these receptors, however, higher doses or more sustained exposures can cause inhibitory effects leading to neuromuscular blockade.It is sometimes reported that people poisoned by organophosphate insecticides experience the same symptoms as nicotine poisoning. Organophosphates inhibit an enzyme called acetylcholinesterase, causing a buildup of acetylcholine, excessive stimulation of all types of cholinergic neurons, and a wide range of symptoms.
The initial symptoms are mainly due to stimulatory effects and include nausea and vomiting, excessive salivation, abdominal pain, pallor, sweating, hypertension, tachycardia, ataxia, tremor, headache, dizziness, muscle fasciculations, and seizures. After the initial stimulatory phase, a later period of depressor effects can occur and may include symptoms of hypotension and bradycardia, central nervous system depression, coma,  muscular weakness and/or paralysis, with difficulty breathing or respiratory failure.From September 1, 2010 to December 31, 2014, there were at least 21,106 traditional cigarette calls to US poison control centers. During the same period, the ten most frequent adverse effects to traditional cigarettes reported to US poison control centers were vomiting (80.0%), nausea (9.2%), drowsiness (7.8%), cough (7.2%), agitation (6.6%), pallor (3.0%), tachycardia (2.5%), diaphoresis (1.5%), dizziness (1.5%), and diarrhea (1.4%). 95% of traditional cigarette calls were related to children 5 years old or less. Most of the traditional cigarette calls were a minor effect.Calls to US poison control centers related to e-cigarette exposures involved inhalations, eye exposures, skin exposures, and ingestion, in both adults and young children. Minor, moderate, and serious adverse effects involved adults and young children. Minor effects correlated with e-cigarette liquid poisoning were tachycardia, tremor, chest pain and hypertension. More serious effects were bradycardia, hypotension, nausea, respiratory paralysis, atrial fibrillation and dyspnea. The exact correlation is not fully known between these effects and e-cigarettes. 58% of e-cigarette calls to US poison control centers were related to children 5 years old or less.