Cancer

The smoking-cancer link is well-known to most: Smoking causes at least 30% of all cancer deaths and 87% of lung cancer deaths, according to the American Cancer Society. Smoking increases the risk of at least 15 cancers, including those of the throat, nasal cavity, lip, mouth, larynx, esophagus, pancreas, cervix, kidney, bladder and stomach, as well as acute myeloid leukemia.

Diabetes

Diabetes and smoking don’t mix. Tobacco use can elevate blood sugar levels and lead to insulin resistance, say experts at the Mayo Clinic in Rochester, Minn. The more you smoke, the bigger your risk: More than 20 cigarettes a day almost doubles smokers’ risk of developing diabetes, compared with nonsmokers’. “People with diabetes already have higher cardiovascular risks,” says David Kendall of the American Diabetes Association. Smoking “just adds to the burden of that risk.”

Heart

Smoking’s assault on the heart doubles or triples the risk of dying from coronary heart disease, the leading cause of death in the USA, the American Heart Association says. The toll is enormous: Each year, nearly 900,000 people die of coronary heart disease.

That’s because smoking narrows blood vessels supplying the heart and other parts of the body; it also promotes blood clotting, raises blood pressure and weakens the biggest artery in the abdomen, sometimes causing it to burst, a condition called abdominal aortic aneurysm, AHA says. Secondhand smoke kills 23,000 to 70,000 people prematurely each year.

Pregnancy and childhood

During pregnancy, smoking increases the risk of complications that can endanger a mother’s life. It nearly doubles the risk of having a low-birth-weight baby and is a leading cause of preterm labor, the March of Dimes says. Smoking causes an estimated 910 infant deaths a year, according to the Centers for Disease Control and Prevention. Babies who breathe in secondhand smoke are at increased risk of sudden infant death syndrome, asthma, ear infections and other problems.

Skin

If you’re going for a rosy glow, nix the smokes.

“The nicotine in cigarettes causes narrowing of the blood vessels in the outermost layers of your skin,” says internist Richard Hurt, director of the Nicotine Dependence Center at the Mayo Clinic. “This impairs blood flow. … Your skin doesn’t get as much oxygen, an important nutrient.”

He says tobacco contains more than 4,000 chemicals, many of which can damage collagen and elastin, fibers that give skin its strength and elasticity. As a result, skin begins to sag and wrinkle prematurely.

Quitting improves skin’s health and appearance, says cosmetic dermatologist Hema Sundaram, author of Face Value. She says smoking also raises the risk of skin cancers, slows its healing rate and worsens hormonal imbalances during perimenopause and menopause.