Brain

Nicotine from cigarettes is as addictive as heroin. Nicotine addiction is hard to beat because it changes your brain. The brain develops extra nicotine receptors to accommodate the large doses of nicotine from tobacco. When the brain stops getting the nicotine it’s used to, the result is nicotine withdrawal. You may feel anxious, irritable, and have strong cravings for nicotine.

Head and Face

Ears

One effect of smoking is reduced oxygen supply to the cochlea, a snail-shaped organ in the inner ear. This may result in permanent damage to the cochlea and mild to moderate hearing loss.

Eyes

Smoking causes physical changes in the eyes that can threaten your eyesight. One of the effects of nicotine from cigarettes restricts the production of a chemical necessary for you to be able to see at night. Also, smoking increases your risk of developing cataracts and macular degeneration (both can lead to blindness).

Mouth

Smoking takes a toll on your mouth. Smokers have more oral health problems than non-smokers, like mouth sores, ulcers and gum disease. You are more likely to have cavities and lose your teeth at a younger age. You are also more likely to get cancers of the mouth and throat.

Face

Smoking can cause your skin to be dry and lose elasticity, leading to wrinkles and stretch marks. Your skin tone may become dull and grayish. By your early 30s, wrinkles can begin to appear around your mouth and eyes, adding years to your face.

Heart

Stressed Heart

Smoking raises your blood pressure and puts stress on your heart. Over time, stress on the heart can weaken it, making it less able to pump blood to other parts of your body. Carbon monoxide from inhaled cigarette smoke also contributes to a lack of oxygen, making the heart work even harder. This increases the risk of heart disease, including heart attacks.

Sticky Blood

Smoking makes your blood thick and sticky. The stickier the blood, the harder your heart must work to move it around your body. Sticky blood is also more likely to form blood clots that block blood flow to your heart, brain, and legs. Over time, thick, sticky blood damages the delicate lining of your blood vessels. This damage can increase your risk for a heart attack or stroke.

Fatty Deposits

Smoking increases the cholesterol and unhealthy fats circulating in the blood, leading to unhealthy fatty deposits. Over time, cholesterol, fats, and other debris build up on the walls of your arteries. This buildup narrows the arteries and blocks normal blood flow to the heart, brain, and legs. Blocked blood flow to the heart or brain can cause a heart attack or stroke. Blockage in the blood vessels of your legs could result in the amputation of your toes or feet.

Lungs

Scarred Lungs

Smokers' lungs experience inflammation in the small airways and tissues of your lungs. This can make your chest feel tight or cause you to wheeze or feel short of breath. Continued inflammation builds up scar tissue, which leads to physical changes to your lungs and airways that can make breathing hard. Years of lung irritation can give you a chronic cough with mucus.

Emphysema

Smoking destroys the tiny air sacs, or alveoli, in the lungs that allow oxygen exchange. When you smoke, you are damaging some of those air sacs. Alveoli don’t grow back, so when you destroy them, you have permanently destroyed part of your lungs. When enough alveoli are destroyed, the disease emphysema develops. Emphysema causes severe shortness of breath and can lead to death.

Cilia and Respiratory Infections

Your airways are lined with tiny brush like hairs, called cilia. The cilia sweep out mucus and dirt so your lungs stay clear. Smoking temporarily paralyzes and even kills cilia. This makes you more at risk for infection. Smokers get more colds and respiratory infections than non-smokers.

DNA

Cancer

Your body is made up of cells that contain genetic material, or DNA, that acts as an “instruction manual” for cell growth and function. Every single puff of a cigarette causes damages to your DNA. When DNA is damaged, the “instruction manual” gets messed up, and the cell can begin growing out of control and create a cancer tumor. Your body tries to repair the damage that smoking does to your DNA, but over time, smoking can wear down this repair system and lead to cancer (like lung cancer). One-third of all cancer deaths are caused by tobacco.

Stomach and Hormones

Belly

Need another reason why smoking is bad for you? Bigger belly. Smokers have bigger bellies and less muscle than non-smokers. They are more likely to develop type 2 diabetes, even if they don’t smoke every day. Smoking also makes it harder to control diabetes once you already have it. Diabetes is a serious disease that can lead to blindness, heart disease, kidney failure, and amputations.

Lower Estrogen Levels

Smoking lowers a female’s level of estrogen. Low estrogen levels can cause dry skin, thinning hair, and memory problems. Women who smoke have a harder time getting pregnant and having a healthy baby. Smoking can also lead to early menopause, which increases your risk of developing certain diseases (like heart disease).