In addition to hammering your lungs, cigarettes—even just one—can mess with your body on a cellular level, leading to...

INFERTILITY
Inhaled cig smoke ages your ovaries, impairing estrogen production and damaging egg DNA. It can also lead to infertility and early menopause.

BREAST CANCER
Dirty chemicals in cigarettes may push breast cells toward cancer. A new analysis revealed that women who smoked had a 24 percent higher chance of developing the disease, per a study in the Journal of the National Cancer Institute.

COLON CANCER
A woman's risk for colon cancer shoots up 19 percent if she's ever smoked. That's more than double a smoking man's increased risk (8 percent), per Cancer Epidemiology, Biomarkers & Prevention.

DNA DAMAGE
Research in the journal Stem Cell found precancerous changes in smokers' lung cells—even when chest X-rays were normal. Translation: Smokers might appear healthy, but their cells can tell a more morbid story.