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Cancer Risk and Prevention

Why People Start Smoking and Why It’s Hard to Stop

About 2 out of 3 of people who smoke say they want to quit. Around half try to quit each year, but few succeed without help. This is because nicotine affects behavior, mood, and emotions.

Studies have found that nicotine addiction can be just as strong as addiction to substances like cocaine and alcohol. In fact, tobacco may be even harder for some people to quit.

Learn more about why people start using tobacco, and what makes quitting so difficult.

Why do people start using tobacco?

Most people who use tobacco start when they are teenagers. Young people are more easily swayed by outside influences to use tobacco, including:

  • Peers who use tobacco
  • Parents or siblings who use tobacco
  • Tobacco use in movies, TV, video games, and on social media
  • Tobacco products that are candy or fruit flavored
  • Tobacco marketing that uses images to appeal to younger people, including messages that smoking makes you thin
  • Price breaks on tobacco products

E-cigarettes and other electronic “vaping” devices have also increased the use of tobacco, especially in young people. Many people think these aren’t as harmful as cigarettes, but that isn’t true. E-cigarettes and vaping devices might also be easier to get and use. They are a way for new users to learn how to inhale and become addicted to nicotine, which can lead to smoking cigarettes and using other tobacco products.

Is tobacco really addictive?

Yes. Tobacco products have nicotine in them, and nicotine is known to be addictive. When you use tobacco products regularly, you can become addicted and physically dependent.

It’s helpful to understand what we mean by this:

Addiction is a mental or emotional dependence on a substance. When you are addicted to tobacco, you have a strong urge to use it. This urge is hard to resist.

Physical dependence is when your body gets used to a substance. Not using it can cause withdrawal symptoms. For tobacco, this can include symptoms like having trouble sleeping, or feeling anxious, grouchy, or hungrier than usual.

People who are addicted to nicotine will still use tobacco even though they know smoking is bad for them. It can negatively affect their lives, their health, and their families. But most people who use tobacco want to quit.

Who is most likely to become addicted?

Anyone who starts using tobacco can become addicted to nicotine (the addictive substance in tobacco products). But the younger you are when you begin using, the more likely you are to become addicted. This is because the brains of young people are still developing. It’s easier for them to become dependent on the good feeling they get from nicotine.

  • Nearly 9 out of 10 adults who use tobacco started before age 18.
  • Almost all started by age 26.
  • 8 in 10 people who start using tobacco as youth or young adults will continue smoking in adulthood.

How nicotine affects you

The nicotine in tobacco affects your brain and body in a few important ways.

Dopamine and adrenaline

Nicotine floods your brain’s “reward circuits” with a chemical called dopamine. Dopamine causes pleasant feelings and distracts you from unpleasant feelings. This makes you want to use more.

Nicotine also gives you a little bit of an adrenaline rush. It might not be enough to notice, but it can speed up your heart and raise your blood pressure.

Nicotine tolerance

As your body gets used to nicotine, you can develop tolerance.

People who use tobacco tend to increase the amount they use each day. When you do this, it raises the amount of nicotine in your blood. Now, you need more tobacco to get the same effect. At this point, you've developed tolerance. To avoid withdrawal symptoms, you have to keep up your tobacco use so the level of nicotine in your blood stays within a comfortable range.

Withdrawal symptoms

When you use tobacco, you can quickly become dependent on nicotine and suffer physical and emotional withdrawal symptoms when you stop.

Nicotine reaches your brain within seconds after using tobacco, but the effects start to wear off within a few minutes. This is especially true for inhaled tobacco products. You might start to feel irritated and edgy. This is what most often leads you to use more tobacco.

Once you consume more tobacco, the unpleasant feelings go away. If you don’t use tobacco again soon, you might have worse withdrawal symptoms. This cycle continues as long as you keep using tobacco.

How powerful is nicotine addiction?

Studies have found that nicotine addiction can be just as strong as addiction to substances like cocaine and alcohol. In fact, tobacco maybe even harder for some people to quit.

About 2 out of 3 of people who smoke say they want to quit. Around half try to quit each year, but few succeed without help. This is because nicotine affects behavior, mood, and emotions.

If you use tobacco to help manage unpleasant feelings and emotions, it can be more difficult when you try to quit. You may also link tobacco with social situations and other activities. All of this make it hard to quit.

How much nicotine is in tobacco products?

The amount of nicotine you get is based on the type of tobacco product you use and how often you use it.

Nicotine in cigarettes

When you inhale nicotine from cigarettes, it is absorbed quickly through your lungs and the linings of your nose and mouth.

The amount of nicotine you actually take in depends on:

  • How many cigarettes you smoke in a day  
  • How many puffs you take on each cigarette
  • How deeply you inhale the smoke

Each cigarette has about 8 milligrams (mg) of nicotine, but only delivers about 1 to 2 mg of nicotine. Regular, menthol, and “light” cigarettes all deliver the same amount of nicotine.

Nicotine in cigars

When you inhale cigar smoke, you absorb nicotine through your lungs, nose, and mouth as quickly as when you smoke cigarettes. If you don’t inhale, the nicotine is absorbed more slowly through the lining of your mouth. This means that when you smoke cigars, you can get nicotine without inhaling the smoke directly into your lungs.

Most full-size cigars have as much nicotine as several cigarettes.

Many popular brands of larger cigars have between 100 and 200 mg, or even as much as 444 mg, of nicotine. The amount of nicotine a cigar delivers can vary a great deal, even among people smoking the same type of cigar.

How much nicotine you take in depends on things like:

  • How long you smoke the cigar
  • How many puffs you take
  • Whether or not you inhale the smoke

Given these factors and the large range of cigar sizes, it’s almost impossible to make good estimates about the amount of nicotine larger cigars deliver.

Small cigars (or cigarillos) are a similar size and shape to a cigarette and have about the same amount of nicotine. If you smoke these like a cigarette (inhaled), you can expect to get a similar amount of nicotine, around 1 to 2 mg.

Nicotine in smokeless tobacco

There are several types of smokeless tobacco including dip, snuff, snus, and chewing tobacco. Nicotine pouches, recreational lozenges, strips, sticks, and small pouches of tobacco are also considered smokeless tobacco. They all provide nicotine when you use them.

Nicotine from smokeless tobacco products enters your bloodstream from your mouth or nose. From there, it’s carried throughout your body.

The amount of nicotine in smokeless tobacco products can vary greatly. How much nicotine you get also depends on things like:

  • The type of smokeless tobacco and the product brand
  • Product pH level (how acidic it is)
  • The amount you use

Studies have shown that the blood levels of nicotine in people who use smokeless tobacco are very similar to the levels in people who smoke cigarettes.

Nicotine in e-cigarettes

The liquid in most e-cigarettes (vapes) has nicotine, but nicotine levels vary greatly between e-cigarette brands and refills.

There is no standard way of listing nicotine levels in e-cigarette product labels. And sometimes, product labels don’t list the true nicotine content. There are some e-cigarette brands that claim to be nicotine-free but have been found to contain nicotine.

Why is it so hard to quit tobacco?

Stopping or cutting back on tobacco causes symptoms of nicotine withdrawal. Withdrawal is physical, mental, and emotional.

Physically, your body is reacting to the absence of nicotine. Mentally, you are faced with giving up a habit, which calls for a major change in your behavior. Emotionally, you might grieve the loss of the habit and how it made you feel.

Studies have shown that smokeless tobacco users have as much trouble giving up tobacco as people who want to quit smoking or using e-cigarettes.

If you’ve used tobacco regularly for at least a few weeks, you’ll have withdrawal symptoms when you suddenly stop or greatly reduce the amount of tobacco you use. There’s no danger in nicotine withdrawal, but the symptoms can be uncomfortable.

Withdrawal symptoms usually start within a few hours and peak about 2 to 3 days later, when most of the nicotine is out of your body. Withdrawal symptoms can last from a few days to several weeks. They get better every day you stay tobacco-free.

Nicotine withdrawal symptoms can include:

  • Urges or cravings for tobacco
  • Feeling irritated, frustrated, or grouchy
  • Trouble focusing
  • Feeling restless or bored
  • Having a hard time sleeping, including trouble falling asleep and staying asleep
  • Having bad dreams or nightmares
  • Feeling more hungry
  • Gaining weight
  • Feeling anxious
  • Feeling sad or depressed
  • Cough
  • Mouth ulcers
  • Headaches

These symptoms can be hard to deal with, and they might cause you start using (or want to start using) tobacco again. It takes most people several tries to quit for good. But there are resources available to help you through the most difficult parts of quitting.

Learn more

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

This content has been developed by the American Cancer Society in collaboration with the to help people who want to learn about quitting tobacco. 

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Last Revised: November 19, 2024

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