When you smoke, the poisons from the tar in your cigarettes enter your blood. These poisons in your blood then:
Make your blood thicker, and increase chances of clot formation
Increase your blood pressure and heart rate, making your heart work harder than normal
Narrow your arteries, reducing the amount of oxygen rich blood circulating to your organs.
Together, these changes to your body when you smoke increase the chance of your arteries narrowing and clots forming, which can cause a heart attack or stroke.
Heart
Smoking damages your heart and your blood circulation, increasing the risk of conditions such as coronary heart disease, heart attack, stroke, peripheral vascular disease (damaged blood vessels) and cerebrovascular disease (damaged arteries that supply blood to your brain).
Carbon monoxide from the smoke and nicotine both put a strain on the heart by making it work faster. They also increase your risk of blood clots. Other chemicals in cigarette smoke damage the lining of your coronary arteries, leading to furring of the arteries.
In fact, smoking doubles your risk of having a heart attack, and if you smoke you have twice the risk of dying from coronary heart disease than lifetime non-smokers.
The good news is that after only one year of not smoking, your risk is reduced by half. After stopping for 15 years, your risk is similar to that of someone who has never smoked.
Stomach
Smokers have an increased chance of getting stomach cancer or ulcers. Smoking can weaken the muscle that controls the lower end of your gullet (oesophagus) and allow acid from the stomach to travel in the wrong direction back up your gullet, a process known as reflux.
Smoking is a significant risk factor for developing kidney cancer, and the more you smoke the greater the risk. For example, research has shown that if you regularly smoke 10 cigarettes a day, you are one and a half times more likely to develop kidney cancer compared with a non-smoker. This is increased to twice as likely if you smoke 20 or more cigarettes a day.
Skin
Smoking reduces the amount of oxygen that gets to your skin. This means that if you smoke, your skin ages more quickly and looks grey and dull. The toxins in your body also cause cellulite.
Smoking prematurely ages your skin by between 10 and 20 years, and makes it three times more likely you'll get facial wrinkling, particularly around the eyes and mouth. Smoking even gives you a sallow, yellow-grey complexion and hollow cheeks, which can cause you to look gaunt.
The good news is that once you stop smoking, you will prevent further deterioration to your skin caused by smoking.
Bones
Smoking can cause your bones to become weak and brittle. Women need to be especially careful as they are more likely to suffer from brittle bones (osteoporosis) than non-smokers.
Brain
If you smoke, you are more likely to have a stroke than someone who doesn't smoke.
In fact, smoking increases your risk of having a stroke by at least 50%, which can cause brain damage and death. And, by smoking, you double your risk of dying from a stroke.
One way that smoking can increase your risk of a stroke is by increasing your chances of developing a brain aneurysm. This is a bulge in a blood vessel caused by a weakness in the blood vessel wall. This can rupture or burst which will lead to an extremely serious condition known as a subarachnoid haemorrhage, which is a type of stroke, and can cause extensive brain damage and death.
The good news is that within two years of stopping smoking, your risk of stroke is reduced to half that of a smoker and within five years it will be the same as a non-smoker.
Lungs
Your lungs can be very badly affected by smoking. Coughs, colds, wheezing and asthma are just the start. Smoking can cause fatal diseases such as pneumonia, emphysema and lung cancer. Smoking causes 84% of deaths from lung cancer and 83% of deaths from chronic obstructive pulmonary disease