Smoking - effects on your body

Nicotine is the addictive drug in tobacco smoke that keeps people smoking. Along with nicotine, a smoker inhales about 7,000 other chemicals in cigarette smoke, many of them produced by burning the tobacco leaf. A number of these compounds are chemically active and trigger profound, damaging changes in the body. Tobacco smoke contains over 70 known cancer-causing chemicals, and smoking harms nearly every organ, causing many diseases and reducing health overall.

Harmful components of tobacco smoke#

• Tar is the name for the solid particles suspended in tobacco smoke. These particles contain chemicals, including cancer-causing substances (carcinogens). Tar is sticky and stains teeth, fingernails, and lung tissue.
• Carbon monoxide is a poisonous gas that is odourless and colourless. In large doses it quickly causes death because it takes the place of oxygen in the blood. In smokers, carbon monoxide makes it harder for oxygen to reach the organs and muscles.
• Oxidising chemicals are highly reactive substances that can damage the heart muscle and blood vessels. They react with cholesterol, leading to the build-up of fatty material on artery walls, which contributes to heart disease, stroke, and blood vessel disease.
• Metals in tobacco smoke include several that cause cancer, such as arsenic, beryllium, cadmium, chromium, cobalt, lead, and nickel.
• Radioactive compounds in tobacco smoke are known to be carcinogenic.

How smoking affects the body’s systems#

Inhaling tobacco smoke damages many of the body’s organs and systems.

Respiratory system#

• irritation of the trachea (windpipe) and larynx (voice box)
• reduced lung function and breathlessness from swelling and narrowing of the airways
• excess mucus in the lung passages
• impairment of the lungs’ clearance system, leading to a build-up of harmful substances, irritation, and damage
• permanent damage to the air sacs of the lungs
• increased risk of lung infection, with symptoms such as coughing and wheezing

Circulatory system#

• raised blood pressure and heart rate
• tightening of blood vessels in the skin, which lowers skin temperature
• less oxygen carried by the blood during exercise
• “stickier” blood that is more prone to clotting
• damage to the lining of the arteries, thought to contribute to atherosclerosis (the build-up of fatty deposits on artery walls)
• reduced blood flow to the fingers and toes
• increased risk of stroke and of heart attack from blocked blood supply

Immune system#

• greater susceptibility to infections such as pneumonia and influenza
• more severe and longer-lasting illnesses
• lower levels of protective antioxidants (such as vitamin C) in the blood

Musculoskeletal system#

• tightening of certain muscles
• reduced bone density

Sexual and reproductive organs#

• in men: lower sperm count, a higher percentage of deformed sperm, genetic damage to sperm, and a higher risk of impotence, which may be due to smoking’s effects on blood flow and damage to the blood vessels of the penis
• in women: reduced fertility, menstrual irregularities or absence of periods, menopause reached one or two years earlier, and an increased risk of cancer of the cervix
• for women over 35 who smoke and take the oral contraceptive pill, a greatly increased risk of stroke and heart attack

Other effects#

• gum disease (periodontitis)
• irritation and inflammation of the stomach and intestines
• increased risk of painful ulcers along the digestive tract
• a reduced ability to smell and taste
• premature wrinkling of the skin
• a higher risk of blindness

Effects on babies#

Smoking during pregnancy can harm an unborn baby, increasing the risk of:

• miscarriage, stillbirth, and premature birth
• low birth weight, which can have a lasting effect on a child’s growth and development. Low birth weight is linked to a higher risk of heart disease, high blood pressure, and diabetes in adulthood.
• attention deficit hyperactivity disorder (ADHD)
• weaker lungs
• cleft palate and cleft lip
• sudden unexpected death in infancy (SUDI)

Passive smoking, where a non-smoking mother is exposed to second-hand smoke, can also harm the fetus. If a parent continues to smoke during a baby’s first year of life, the child has a higher risk of ear infections, respiratory illnesses such as pneumonia and bronchitis, and meningococcal disease.

Diseases caused by long-term smoking#

A person who smokes throughout their life is at high risk of a range of potentially fatal diseases, including:

• cancers of the lung, mouth, nose, larynx, tongue, nasal sinus, oesophagus, throat, pancreas, bone marrow (myeloid leukaemia), kidney, cervix, ovary, ureter, liver, bladder, bowel, and stomach
• lung diseases such as chronic bronchitis and chronic obstructive pulmonary disease (COPD), which includes obstructive bronchiolitis and emphysema
• heart disease and stroke
• ulcers of the digestive system
• osteoporosis and hip fracture
• type 2 diabetes
• rheumatoid arthritis
• poor blood circulation in the hands and feet, which can cause pain and, in severe cases, gangrene and amputation

Key points#

• Nicotine is the addictive drug that keeps people smoking, but tobacco smoke also contains about 7,000 other chemicals, including over 70 known carcinogens.
• Carbon monoxide in tobacco smoke is odourless and colourless and, in large doses, can quickly cause death because it displaces oxygen in the blood.
• Inhaling tobacco smoke damages many of the body’s organs and systems and causes many serious diseases.
• Smoking during pregnancy and exposure to second-hand smoke can harm babies before and after birth.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).