Several posts have been seen where it has been suggested that nicotine overdose by vaping has a significant risk of harm (or worse). Some useful points related to this are laid out below. _________________________________________ - The lethal dose for nicotine LD50  is 50mg per kilo bodyweight inhaled or injected (but not ingested). This is the legally-accepted dose for lethality , and also a value better supported than the mythical LD50 dose of 60mg, by the only proper research into nicotine toxicity ever carried out, by Prof Mayer of Graz. - LD50 for nicotine by ingestion (swallowing) has never been established, see . In practice it appears almost impossible to die from swallowing nicotine as the dose required is so large, or some form of anaesthetic is needed and therefore 'death by nicotine' is an inaccurate description: a cocktail of drugs is required. - There is nothing abnormal about fatality being possible from dietary materials such as this (nicotine is a normal part of the diet, everyone consumes it, and everyone tests positive for it). Vitamin D, vitamin A, iron and several other nutrients have the same effect (death from overdose). In other words the only difference between a nutrient (or a medicine) and a poison is the dose. All materials are in fact fatal, given a large enough dose. - In terms of the tiny amounts of nicotine that tobacco consumers or vapers take as dietary supplements (which is what they are doing), people have a factor-10 difference in tolerance. Some cannot vape 12mg and must use 6mg (0.6% nic solution) to avoid any symptoms of OD, others must vape 60mg (6% nic) in order to avoid smoking, and feel no ill effects. So there is clearly a massive variation in tolerance to this material - and in fact we know it is 10x. There is a bell curve of nicotine tolerance in the population, with most people being around a median at somewhere between 18mg and 24mg (in chosen e-liquid strength as a demonstrated measure of tolerance), and outliers at 6mg and 60mg at each end . - According to Prof Hajek (of QMUL), no lasting ill effects can result from inadvertent consumer nicotine overdose. Multiple use of NRTs, cigarettes, ecigs or whatever else will make you sick enough to stop, like drinking too much coffee. The excess nicotine is rapidly metabolised and eliminated, and there is no harm. - Nicotine is not associated with cancer or any other disease. No one can produce any evidence that nicotine consumption has any clinically-significant negative health effect in humans, and there is a mountain of facts and evidence to support this. It is not advised for certain persons, such as the pregnant, but is likely to be far less harmful than smoking for such persons. - Sometimes you will read researchers making statements such as, "Nicotine promotes cancer because it increases blood flow and growth of new blood vessels, causing them to proliferate, thus enabling growth of tumours and promoting cancer". Equally, you will hear, "Nicotine must not be used before or after surgery because it restricts blood flow and growth of new blood vessels, thus hindering healing, and may result in failure of the treatment. Therefore we will not operate on smokers or vapers" - from hospital staff. Since these are directly opposing statements, you might legitimately ask which of the two groups is lying - because one of them is. Or both. Risk from vaping is minimal So just as you can drink a quart of coffee and recover, the same applies to over-vaping. It appears impossible to suffer any ill effects - including the heart stopping or whatever  - although the experience will not be pleasant for those with a low tolerance to the material (which is 99% genetic rather than related to body weight or consumption history: if you cannot over-vape 6mg and are obviously therefore very sensitive to the material, then it is extremely unlikely that a history of high consumption will change that significantly). All these effects are on average. This means for the average, normal person. Some people are not average and may have a genetic predisposition to far greater effects from any material of this nature. We can see this demonstrated by the wide range in tolerance to nicotine that is so clear from our experience . -------------------- Notes  This means the dose expected to kill half of adults who receive it ('lethal dose in 50% of cases').  This is the dose accepted as LD50 lethal in courts of law internationally. It would be difficult to establish cause of death due to nicotine poisoning legally with a smaller dose since there is a mountain of case law on the applicability of the SD rat LD50 to humans for this general purpose, and no evidence of any significantly lower dose of nicotine ever causing any human fatality. Thus the accepted legal dose for nicotine fatality by injection etc (it requires a huge amount more for ingestion and indeed the amount has never been established for this route ) is therefore 75kg x 50mg = 3,750mg for an average person, taken to mean someone of 165 lbs. Smaller amounts than this are often quoted, but are a myth since there is no evidence to support such claims (which probably exist because there is a significant commercial value to such myths). Prof Mayer has stated that the LD50 is probably lower than this (~1,000mg), but there is too little evidence to establish a reliable figure as there are so few cases of fatal nicotine poisoning, and in almost all cases the subject was anaesthetised in some way to prevent emesis or other evasion of the desired result. In other words, successful suicide by nicotine ingestion requires (a) a very high dose compared to the myths, and (b) other drugs to stop the vomiting. There is a problem relating overall nicotine delivery to a fatal plasma nicotine measurement, which Prof Mayer acknowledges, due to (a) the very rare cases of fatality, and (b) no real evidence for equating the two values. All we know is that the required dose is substantial, certainly orders of magnitude larger than the accepted myth, and much closer to the more realistic legally-accepted rat LD50 normally used in poisoning cases (because in contrast with the very rare nicotine poisoning events, cases of poisoning from other materials are vastly more common, and the LD50 for multiple poisons in humans is known to align closely with the value in the Sprague-Dawley rat).  It has apparently been impossible to establish a fatal dose by ingestion since, in the human adult, nicotine swallowed is ejected by emesis (it's vomited out due to an automatic reflex). In every case of fatal nicotine ingestion known, simultaneous anaesthesia was involved in order to successfully suppress the vomit reflex. Ingestion of 1,500mg is known to be survivable with no lasting ill effect. It is probably possible to say that death by nicotine ingestion (swallowing) is virtually unknown: death was caused by a drug cocktail. Children are a different matter, and it is possible that the vomit reflex is not developed and sensitivity is far higher than in adults. However careful note must be made of the fact that child deaths by ingestion of nicotine-containing vaping products may not exist. We know of two cases: one was subsequently revealed to have been due to choking on a swallowed cartomiser as against nicotine poisoning (although this was perhaps obscured by the media); the other is current at the date of writing and a full report is not available yet.  When using traditional vaping hardware such as a 510 atomiser, clearomiser, or tankomiser. RBAs, in contrast, deliver massive vapour volume and therefore nic strength is normally reduced dramatically, often to 6mg or even 3mg for those who would probably use 18 or 24mg in a clearo.  All medicines, drugs and consumer materials are described in terms of their average effect. Some people are not average: some can receive a dose several times that which would cause problems for others. Or to look at this the other way around, some people will be poisoned by a dose several smaller than that considered normal by another. We know this range is 10x for nicotine in humans.  From current research and statements by Prof Mayer, Prof Hajek and others, it appears impossible or unlikely that even extreme overdose by inhalation (i.e. massive over-vaping) can be harmful: i. A single dose by inhalation is not enough to kill (i.e. by stopping the heart); ii. Over-consumption rapidly becomes extremely unpleasant; iii. Nicotine poisoning has no harmful after-effect. Of course, as with any other evaluation of this type, it applies on average. Some people are not average, and highly-sensitive people must exist even though rare.