So what does nicotine really do to your body? The answer might surprise you.

It’s safe to say nicotine has a pretty bad reputation.

From exaggerated claims about how toxic it is to the unfortunately widespread myth that it causes cancer, it’s long been viewed as a menace. As soon as e-cigarettes came on the scene, they were viewed as a menace too, largely because most contain it. Nicotine is highly addictive, critics argue, causes heart problems, harms teenagers’ brains and more.

This perception has real-world consequences too. In Australia, you can vape, but nicotine-containing liquids, in particular, are banned from domestic sale across the country.

As the most notorious chemical in tobacco, it’s easy to understand why nicotine is so vilified. But the fact that people and some governments think it’s dangerous doesn’t mean it really is.

If you want the facts about how nicotine affects your body, you have to follow the evidence, not people’s perceptions.

E-cigarettes are still fairly new, but we’ve had sources of nicotine that aren’t cigarettes for a long time. With evidence from nicotine replacement therapy and other tobacco harm reduction products like snus, we can get to the bottom of whether nicotine is harmful, and what it does to your body.

Nicotine Basics: What is it? Where is it Found? How Much Nicotine is in a Cigarette?

Nicotine is the most well-known chemical found in tobacco. It’s an alkaloid, which means it contains nitrogen and is chemically similar to things like caffeine and cocaine.

As well as the tobacco plant, it’s also found in potatoes, tomatoes and aubergine, though in very tiny amounts. To compare, there’s about 20 mg of nicotine in 1 g of tobacco, compared to 0.0001 mg per 1 g of aubergine. This is also the vegetable with the highest nicotine content, so amounts in tomatoes and potatoes are even lower.

Cigarettes usually contain about 10 mg of nicotine. However, you don’t actually get all of this when you smoke.

The tip burns throughout smoking, which leads to some wasted nicotine. Some nicotine is also inevitably caught in the filter, reducing the amount that gets to you. Finally, only some of the nicotine (the non-ionized nicotine) can actually be absorbed by the body. In the end, you only actually absorb about 1 mg of nicotine per cigarette.

How Nicotine is Absorbed by the Body

When you smoke a cigarette, nicotine passes through the lung’s membranes and into the bloodstream. Generally, if nicotine is in an alkaline environment, it will pass through into the blood more effectively. This is why tobacco companies have adjusted the ingredients of cigarettes to increase the pH (i.e. make it more alkaline) and get smokers more nicotine.

After it reaches the bloodstream, the nicotine makes its way to your heart. There, it’s transferred to your arteries, and up to your brain. This whole process takes between 10 and 20 seconds, and it’s one of the reasons you get so much nicotine so quickly from smoking. Exactly how much nicotine you get from smoking can vary based on your brand and how you smoke it.

For e-cigarettes, things are a little different. As the Royal College of Physicians argues in its report (Report page 84, PDF page 98), it seems like most of the nicotine from vaping is absorbed by the mouth and upper throat, not the lungs. The nicotine absorbed in this way still reaches the blood, but notably less quickly than it does when you smoke. This is one of the reasons that e-cigarettes are less addictive than traditional tobacco cigarettes.

What Are The Short Term Effects of Nicotine On Your Body?

When you vape or smoke, the short-term effects of nicotine are the main thing you’ll notice. This is a bit more complicated than you might imagine, though.

Nicotine is a stimulant, so as well as creating a pleasurable feeling, it also raises your heart rate, improves your ability to pay attention and boosts memory. But it has a “biphasic” action: if you have a little bit, it acts as a stimulant, but if you have more, it can relax you.

For smokers, this means that you inhale more deeply to get a more relaxing effect from nicotine and take shallower inhales to get more of a stimulant effect. Generally, smokers will do this as needed without even necessarily realising it.

For vaping, the majority of devices make you press a button to inhale, but the same basic rule applies. If you want a more relaxing effect, take big puffs and keep vaping until you feel relaxed. But if you want a pick-me-up, take shallower puffs and don’t vape for too long.

How Does Nicotine Create its Effects?

Nicotine’s effects are the result of its ability to bind to certain receptors in the brain. Think of this like a key fitting in a lock: the key has a unique shape, and this has to match the inside of the lock for it to be able to open it. The “locks” that nicotine fits in are called nicotinic acetylcholine receptors (nACHRs, for short).

Things get a lot more complicated, though. For example, each nACHR is made from five subunits, and the combination of these effects how the receptor responds to nicotine. The range of different subunits and the result types of nACHR receptors are one of the reasons nicotine has such wide-ranging effects.

When the nicotine binds to the receptors in your brain, it stimulates the release of “neurotransmitters.” These are like chemical messengers used by the brain to send signals, with the most well-known being dopamine.

Dopamine is an often-misunderstood neurotransmitter but basically, serves to make you remember rewards. This is why it has a central role in the development of most addictions. However, it also plays a role in remembering negative experiences, and its role is generally much more complicated than the typical “reward chemical” explanation suggests.

Dopamine isn’t the only neurotransmitter affected by nicotine, though. Others affected include:

Serotonin . Among other things, this affects your moods.

. Among other things, this affects your moods. GABA (gamma-aminobutyric acid) . This reduces the activity of the neurones it binds to.

. This reduces the activity of the neurones it binds to. Glutamate . This is like the opposite of GABA – it’s an “excitatory” neurotransmitter.

. This is like the opposite of GABA – it’s an “excitatory” neurotransmitter. Noradrenaline. This is often called the “stress hormone.”

While there’s a lot of complexity in exactly what nicotine does, the range of neurotransmitters it affects and the diversity of nACHRs is why it has so many different effects on users.

These factors also go some way to explaining why nicotine is addictive. When nicotine regularly stimulates the nACHR receptors, the body reacts by reducing the number of receptors and making less acetylcholine itself.

This means that the same amount of nicotine won’t have the same effect anymore. This is called “tolerance” to nicotine’s effects. And if you don’t consume nicotine, the adaptations your body has made start to cause problems.

After having adapted so that you need nicotine to feel normal, not having nicotine leaves you with a deficiency. This creates withdrawal, and unpleasant symptoms like anxiety, restlessness and the inability to concentrate.

This is why when you’re quitting smoking, alternative nicotine sources like e-cigarettes or nicotine replacement therapies can be really helpful. It lessens these symptoms and makes the transition to being smoke-free a lot smoother.

Is Nicotine Harmful?

Now we know what nicotine is and what happens when you consume it, we can get to the most crucial question. One of the assumptions behind many of the arguments against vaping is that nicotine is harmful, and should be avoided.

This seems to make perfect sense if you don’t know too much about how cigarettes cause harm. The simplistic take on the issue is that nicotine is in tobacco, and tobacco is bad for you, so nicotine is bad for you.

However, the old adage that smokers “smoke for the nicotine but die from the tar” shows the big flaw in this argument. Nicotine may be the most well-known chemical in cigarettes, but that doesn’t mean it’s responsible for all of their negative effects. The big question is whether it’s responsible for any of them.

So is nicotine as safe as caffeine? What happens to people who use nicotine long-term without smoking? Should vapers worry about how much nicotine they’re consuming?

How Toxic is Nicotine?

Although this has been covered many times, it’s worth stressing that there is a firmly-entrenched myth that about 60 mg of nicotine is enough to kill an adult. That would be just over a few ml of an 18 mg/ml e-liquid.

This is completely false, and the figure is based on nothing other than some questionable experiments from the 19th century. In the experiment, the researchers reported seizures and other serious symptoms after claiming to have consumed a few cigarettes’ worth of nicotine (about 4 mg). We’d have probably noticed the chain-smokers collapsing in fits in beer gardens on a regular basis if this was true.

The short version is that if you look at the more reliable evidence, the lethal dose is actually about 500 to 1,000 mg, and probably even more than that. This is far beyond the amount you could reasonably be exposed to by vaping or smoking. If you consider the fact that one of the first symptoms of having too much nicotine is vomiting and nausea, the chances you’ll have problems because nicotine is “toxic” is vanishingly small.

The only exception is for people who mix their own e-liquid (“DIY” mixers). If you have a strong nicotine base – for example, 72 mg/ml – you have something with the potential to be genuinely dangerous. Nicotine can absorb through your skin, so you should always wear gloves when mixing. And hopefully, it should go without saying that you should never vape undiluted nicotine base.

Does Nicotine Cause Cancer?

One of the biggest misconceptions about nicotine is that it causes cancer.

A surprisingly large number of smokers think this is true – anything from just over half to two-thirds, based on research. Again, the apparent reasoning behind this is simple: you smoke for the nicotine, smoking causes cancer, therefore nicotine must cause cancer.

The problem, of course, is that nicotine doesn’t cause cancer at all. There is some evidence that nicotine could promote the growth of tumours, but it doesn’t actually cause cancer. Additionally, studies finding this generally use bigger amounts than most smokers or vapers would be exposed to.

One of the most well-known studies on the topic used data from the Lung Health Study. This found that although cigarette smoking was linked to cancer, there was no association between using nicotine replacement therapy and getting cancer. Their smoking and nicotine patch/gum use was assessed for five years, and then there were another seven and a half years of follow-up.

Other evidence also shows that nicotine is unlikely to be a cause of cancer. One especially notable source of data comes from snus, a form of smokeless tobacco popular in Sweden. Since you use it by holding it in your mouth, most of the focus has been on oral cancer, but many other cancer sites have been considered too. Overall, there is not much support for a link at all.

Some studies look like they support a link between using snus and oral cancer. However, this is not true for studies of modern snus or snus from Sweden. Apparent links also disappear when researchers properly account for the known increase in risk from smoking and drinking alcohol.

In summary, although smoking causes various cancers, we have plenty of evidence on people who use nicotine without smoking that refutes the possible link.

Nicotine and Your Heart

Although a lot of people are confused about the potential link between nicotine and cancer, the most common risks of nicotine you’ll hear about are the ones to your heart. It seems to make sense, too – nicotine is a stimulant, so it just inherently seems to “fit” that it would be dangerous for your heart.

There is some truth to this overall idea. When you consume nicotine, it does have some immediate effects on your heart, explained in this post from Bernd Mayer (though it’s a bit heavy on jargon).

The short version is that the noradrenaline released when you consume nicotine leads to an increase in heart rate. This reduces the amount of blood reaching your heart and makes it work harder, but the effects are quite mild and disappear quite quickly.

The effects of nicotine on blood pressure are quite similar. It does increase blood pressure, but then it decreases again and the impact doesn’t seem to be a cause of concern. (There is also some evidence that suggests nicotine may lead to a long-term decrease in blood pressure.)

There is one potentially serious effect, though. This relates to the endothelium, which is a thin layer of cells that line the inside of your blood vessels. These cells have a big role to play in how your blood vessels function, and if something goes wrong with them it can cause many problems. These include strokes, heart attacks, coronary artery disease, atherosclerosis (clogged arteries), peripheral artery disease (narrow arteries) and high blood pressure.

Long-term nicotine exposure does impact on the epithelial cells, so over time, it’s possible that nicotine use could lead to problems. But plausibility is just the start; what matters is whether it actually happens in real nicotine users.

The Lung Health Study mentioned earlier was used to look at whether nicotine use (in the form of gum) is linked to deaths from cardiovascular issues or people being hospitalised for them. The results showed no link between nicotine gum use and cardiovascular problems. Most side effects reported in the study were also mild and went away quickly. Other research has shown similar results.

A meta-analysis published in 2014 looked at 21 different trials on nicotine replacement therapy and found that there was no clear evidence of risk to the heart and blood vessels. There is quite a lot of uncertainty in this result, though, and it still technically possible that there is a real increase in risk. Research on snus users also has similar results.

Overall, it’s safe to say that if it does impact your risk of heart problems, it will be a much smaller risk than from smoking. And that’s really the most important thing for vapers. If you don’t smoke, though, this is a good reason to think twice about starting to vape nicotine-containing juices.

Does Nicotine Harm Teenage Brains?

Another common claim about nicotine’s risks is especially popular in the US: “Nicotine harms teenage brains!”

The problem is that there isn’t much evidence to base this on.

There are animal studies that support the claim, but that doesn’t mean the same thing happens in humans. The only evidence there is of impacts on teenage human brains comes from smokers, but since they smoke, it’s hard to be sure it’s due to the nicotine and not something else. Just like with cancer and heart problems, it could be that other things in smoke that cause problems, not nicotine.

So it could be true that the effects seen in teenagers who smoke are largely due to nicotine, but it could also be true that they’re nothing to do with it. In fact, if this post has shown anything, it’s that the problem often isn’t the nicotine. But even if it is in this case, smoking will expose you to just as much (or even more) nicotine, as well as loads of much more harmful chemicals.

So, is Nicotine Harmful Overall?

This isn’t an easy question to answer, but the shortest response is “not really, or at least not very harmful.” This is why people often compare nicotine to caffeine. Although you’d have to do some quite detailed comparisons to really make the case strongly, the basic points are fair.

Like nicotine, caffeine is a mild stimulant with some short-term effects on the body. It isn’t completely and utterly benign, but most people who consume it do so without issues. It isn’t that addictive, but some people can and do get addicted to it. More detailed comparisons – for example, how likely each is to cause heart problems – isn’t exactly easy to do, but also isn’t really needed.

The point of comparing nicotine to caffeine isn’t to say that nicotine’s risks are exactly like caffeine’s risks. It’s more of a broad point about the ball-park amount of risk from both. It’s more about saying “we shouldn’t be any more worried about people using clean sources of nicotine than we are about people drinking coffee.”

Of course, if you don’t smoke, you’re not advised to start vaping as casually as you might pick up a cup of coffee. But if you do smoke, you definitely shouldn’t let the fact that you’d still be consuming nicotine put you off trying to switch. Out of the multitude of risks from smoking, nicotine is among the least of your concerns.