Harms of smoking and nicotine addiction

10Why is smoking one of the most serious health risk factors?

Smoking is the leading cause of preventable death in the world. Tobacco smoke contains thousands of chemicals, dozens of them known carcinogens, along with carbon monoxide, which takes the place of oxygen in the blood, and tar, which settles in the lungs.

The problem is that most of the harm builds up silently over years, so a young smoker feels “fine” until the problem appears in their forties or fifties as angina, a heart attack, a tumor, or permanent shortness of breath.

11What does smoking do to the organs of the body?

There is no “safe” number of cigarettes; even light smoking clearly raises the risk of heart disease compared with not smoking, although the risk rises with the amount and the number of years.

12What are the harms of shisha, and is it milder than cigarettes?

Many people think shisha is milder, but in a single session it can expose the person to far more smoke than a cigarette. According to the US Centers for Disease Control and Prevention:

Like cigarettes, shisha is linked to heart and lung disease and to cancers of the mouth and lung, in addition to cases of carbon monoxide poisoning that show up as headache, dizziness, and fainting, especially in enclosed, poorly ventilated places.

13Vapes and heated tobacco: are they less harmful?

E-cigarettes do not burn tobacco, but the World Health Organization describes them as harmful and unsafe: their aerosol carries nicotine and substances that can irritate the lungs, they cause dependence, especially in teenagers, their liquid is a poisoning hazard for small children, and many people use them together with cigarettes, combining the harms of both. Heated tobacco contains real tobacco and releases toxic emissions, many of them similar to cigarette smoke, so it should not be presented as safe.

We present the full evidence, including when vaping may help a smoker quit and when it harms, on the page E-cigarettes (Vapes): The Facts, Without Exaggeration or Understatement.

14How does nicotine harm the teenage brain?

The brain keeps developing until roughly the mid-twenties. According to the US Centers for Disease Control and Prevention, nicotine can harm the parts of the brain responsible for attention, learning, mood, and impulse control. Early exposure may also make the brain more prone to addiction to other substances later.

That is why vaping at school age is an early gateway to a dependence that can last for years, and it may come with falling grades, mood swings, and anxiety, even if it looks like an “innocent experiment.”

15What is the effect of smoking on pregnancy and fertility?

• It reduces fertility in both men and women, and is linked to poorer sperm quality and erectile problems.
• In pregnancy it raises the risk of miscarriage, premature birth, low birth weight, and placental problems.
• A mother’s smoking, or an infant’s exposure to smoke, is linked to a higher risk of sudden infant death.
• Exposure to smoke in childhood increases asthma attacks and ear and chest infections.

16What are the harms of secondhand smoke to the family?

Secondhand smoke kills more than 1.6 million people a year according to the World Health Organization. In adults it raises the risk of heart disease and lung cancer, and in children it causes asthma attacks and repeated chest and ear infections. Opening a window or smoking in another room does not protect children adequately; the only effective solution is a smoke-free home and car.

There is also what is called “thirdhand smoke”: smoke residue that sticks to curtains, furniture, and clothes, which small children touch and then put their hands in their mouths.

17Does smoking harm mental health and daily life?

Despite the common idea that a cigarette “calms the nerves,” regular smoking is linked to higher levels of anxiety and tension between cigarettes because of repeated withdrawal cycles. Many people who quit notice improved mood and less anxiety after getting past the first weeks.

• Money: What is spent on cigarettes, shisha, and vapes each month is a large sum that builds up over the years at the expense of the family’s needs.
• Sleep: Nicotine is a stimulant that can delay and interrupt sleep, and a craving may wake the smoker at night.
• Exercise and activity: Shortness of breath reduces the ability to move and play with your children.
• Relationships: Arguments about smoking at home, and a smell that bothers your partner.

18Can the harms of smoking go away after quitting?

Many of them can, and some decrease gradually without disappearing completely. The risk of heart disease drops clearly within the first year, and the risk of stroke and lung cancer falls over years. Damage that has already occurred in the lungs, such as emphysema, does not return to how it was, but quitting stops it from getting worse. The full timeline of the benefits of stopping is on the smoking treatment page.