What’s in a cigarette?

  • Cigarettes release over 5,000 different chemicals when they burn
  • Many of these chemicals are poisonous and up to 70 cause cancer

A cigarette is much more than chopped up tobacco leaves wrapped in paper. Cigarettes release thousands of dangerous chemicals when they burn.

Roll-up tobacco cigarettes are not any safer. They contain the same cancer-causing chemicals as manufactured cigarettes.


What’s in tobacco smoke?


Tar is a sticky-brown substance that collects in the lungs when you breath in cigarette smoke. It can stain fingers and teeth a yellow-brown colour.

Tar contains cancer-causing chemicals. But it can cause more than just lung cancer. It also increases the risk of other lung diseases. This includes emphysema and chronic obstructive pulmonary disease (COPD).


Carbon Monoxide

Cigarette smoke contains a poisonous gas called carbon monoxide. You can’t smell, see or taste it.

Carbon monoxide stops your blood from carrying as much oxygen. This means your heart must work harder, and your organs don’t get the amount of oxygen they need. This increases your risk of heart disease and stroke.



Nicotine is a very addictive drug. Most people who smoke regularly don't do so out of choice – it’s because they have a nicotine addiction.  

Some people associate smoking with feeling less stressed and anxious. But this is only because it reduces the unpleasant symptoms of nicotine withdrawal for a short time.

But nicotine is harmless compared to other substances in tobacco smoke. And studies have shown that nicotine replacement therapy (NRT) doesn't cause cancer.

NRT helps people deal with cravings when they are trying to cut down or stop smoking. It comes in many forms including patches, lozenges or gum.

Find out more on our how do I stop smoking page.


What ingredients in cigarettes cause cancer?

Up to 70 of the chemicals found in tobacco smoke cause cancer. Many of these cancer-causing chemicals in tobacco smoke have other surprising uses.



  • 1,3-Butadiene is used in rubber manufacturing

  • Arsenic is a poison

  • Benzene is an industrial solvent, refined from crude oil

  • Beryllium is used in nuclear reactors

  • Cadmium is used in batteries

  • Chromium is used to manufacture dye, paints and alloys

  • Formaldehyde is used as a preservative in science laboratories and mortuaries

  • Polonium-21 is a highly radioactive element

  • Polycyclic aromatic hydrocarbons are a group of dangerous DNA-damaging chemicals, including benzo(a)pyrene 


Low tar, 'light' and filtered cigarettes are not safer options

There is no such thing as safe tobacco.

Smoking filtered, low-tar, or ‘light’ variations of cigarettes doesn't reduce overall risk of disease.

And since 2003 it's been against the law to call tobacco products ‘light’, ‘mild’ or ‘low-tar’ versions. Using these words can make people wrongly believe that they are safer or healthier options.


How do chemicals in tobacco smoke lead to cancer?

Each cigarette you smoke can lead to DNA damage. And it is the build-up of damage in the same cell that leads to cancer.

Here are some of the ways that harmful chemicals in tobacco smoke can cause damage in the body:


Some chemicals in tobacco smoke damage DNA.

The DNA in all our cells controls how they grow and behave. If DNA is damaged, things can go wrong.

Some chemicals in cigarette smoke cause damage to parts of the DNA that normally protect our cells from cancer.  And this can lead to cancer cells growing out of control.


Chemicals in tobacco smoke are even more dangerous as a mix.

This is because there are chemicals in tobacco smoke that can make other harmful chemicals stick more strongly to DNA.

There are also chemicals that stop our cells from repairing DNA damage. This makes it even more likely that damaged cells will turn cancerous.


Chemicals in tobacco smoke harm the cleaning system that our bodies use to remove toxins.

For example, chemicals in cigarette smoke kill cilia. Cilia are the little hairs which usually keep our airways clear from dirt and infections.

This means people who smoke are less able to handle toxic chemicals than those with healthy lungs and blood.


It’s never too late to stop smoking

If you smoke, the best thing you can do for your health is to stop – it could even save you thousands of pounds each year. The NHS has a calculator to work out how much you could save by stopping smoking.

Stopping can be difficult, but it is possible. And the number of people who have stopped smoking is increasing.

Using prescription medicine with support of a free, local stop smoking service, is most likely to help you to stop for good. But how you chose to quit is up to you.

Read more on how to stop smoking.


Action on Smoking and Health. What’s in a cigarette (2018).

International Agency for Reseach on Cancer. Personal Habit and Indoor Com bustion: Tobacco Smoking. Vol  100 E, 377–504 (2012). https://www.ncbi.nlm.nih.gov/books/NBK304395/

US Surgeon General. How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease. (2010).

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