Smoking and tobacco: health risks, how quickly they fall and how to stop

Tobacco smoke contains over 5,000 chemicals, according to Cancer Research UK, and at least 70 of them are known to cause cancer. When you inhale, these chemicals enter the lungs and spread through the whole body. The main way cancer develops is through damage to the DNA in cells, and the chemicals in smoke also make it harder for cells to repair that damage, so it builds up over time.

The British Heart Foundation explains how smoking affects the heart and circulation. The chemicals make the walls of your arteries sticky, so fatty material sticks to them and begins to clog the arteries. If arteries carrying blood to the heart become clogged, it can lead to a heart attack, and if those to the brain become clogged, a stroke. Smoking can also increase the risk of blood clots, cause an instant rise in heart rate and blood pressure, and reduce the oxygen delivered around the body.

All forms of tobacco carry risk. Cancer Research UK lists cigarettes, cigars, pipes, shisha and smokeless tobacco, and says there is no safe level of tobacco use.

Cancer Research UK says smoking causes at least 16 types of cancer, and that the link is very clear. They include cancers of the nose and sinuses, mouth, throat (pharynx), voice box (larynx), food pipe (oesophagus), lung, breast, liver, stomach, kidney, pancreas, bowel, ovary, bladder and cervix, as well as some types of leukaemia.

Smoking also causes other illnesses. The charity notes that it causes other diseases too, such as heart disease and various lung diseases, so the harm is not limited to cancer.

Both the length of time you have smoked and the amount you smoke matter. Cancer Research UK says the number of years you smoke for affects your cancer risk the most, and that the more cigarettes you smoke a day, the higher the risk. Reducing the number is a useful first step, but stopping completely is the aim.

People who smoke often have a cough, and it is easy to dismiss. Cancer Research UK points out that a cough can be a sign of lung cancer as well as other conditions. It advises telling your doctor if you have a persistent cough, a change in a cough you have had for a while, breathlessness, or any other symptom that is new for you or will not go away.

Do not wait for a screening invitation or a routine check. If you are a current or former smoker and notice new breathlessness, chest pain, coughing up blood or unexplained weight loss, see a GP promptly. If you have severe chest pain or severe difficulty breathing, call 999.

The NHS Better Health site sets out a timeline of recovery. After 20 minutes your pulse rate will already be starting to return to normal. After 8 hours oxygen levels are recovering and the level of harmful carbon monoxide in your blood will have halved. After 48 hours carbon monoxide has dropped to that of a non-smoker, your lungs are clearing mucus and taste and smell are improving. After 72 hours breathing feels easier.

Over the following months circulation improves, and after 3 to 9 months coughs, wheezing and breathing problems improve as lung function increases by up to 10%. After 1 year your risk of heart attack is half that of a smoker, and after 10 years your risk of death from lung cancer is half that of a smoker.

It is never too late. The British Heart Foundation says that, on average, people who quit in their 30s add 10 years to their life, and even quitting at 60 adds 3 years. Cancer Research UK says everyone who smokes can benefit from stopping, even if they have smoked for years.

The NHS says local stop smoking services are free and can improve your chances of quitting for good. You will normally be offered one-to-one sessions with an adviser, and some areas also offer group and drop-in services, with sessions available by phone or online in some places. At the first meeting you talk about why you smoke, choose a quit date and may have a breath test that shows the level of carbon monoxide in your body.

Treatments include nicotine replacement products such as patches, gum, lozenges, inhalators and sprays, and stop smoking tablets such as varenicline, cytisinicline or bupropion. The NHS says there is evidence that e-cigarettes can help people stop smoking, although they are not currently available as medicines and so cannot be prescribed on the NHS, and some local services offer a free starter pack. Support usually lasts up to 12 weeks.

Your GP, pharmacist or health visitor can refer you, or you can contact your local service yourself. The NHS also notes that reaching 28 days smoke free makes you much more likely to quit for good.

NHS stop smoking support is the best-evidenced route and is free to use. Some people also use private hypnotherapy, programmes or e-cigarette products. If you choose these, it is sensible to tell your GP or stop smoking adviser, because they can combine them with proven treatments rather than replace them.

Smoking is also a modifiable risk factor for other conditions listed across the NHS, including cancers of the stomach, bowel and ovary, osteoporosis, and cardiovascular disease. Stopping is one of the most valuable single steps for health, whatever your age.