You've made three visits to the clinic with a sniffy nose, and just finished six weeks of rotating antibiotics for a "sinus infection." These bacteria-killing medicines were once called "wonder drugs," but they are about to have a not-so-wonderful effect on your digestive tract.

Before taking those pills, you had up to six pounds of bacteria living quietly in your gut -- outnumbering your own body's cells ten to one. Now that your digestive flora has been exterminated by antibiotics, the sludge filling your intestine is the perfect environment for a highly unwelcome visitor -- a spore-forming germ called Clostridium difficile.

A cousin of the gem responsible for gas gangrene, this noxious invader loves airless oxygen-depleted environments and quickly makes itself at home by coating the inside of your colon with a gluey mucus layer that causes diarrhea, fever and abdominal pain. Your clueless doctor is likely to prescribe more antibiotics to treat the symptoms -- wrong move! Now C-Diff trenches in for a permanent stay. A blood test shows your system is flooded with toxins, and a colonoscopy reveals an inflamed, exquisitely tender colon coated with a tightly adherent bacterial pseudomembrane -- a relapsing colitis that kills tens of thousands of Americans annually, particularly older victims stuck in nursing homes.

To restore your digestive tract to its former condition, your doctors are now facing a problem roughly comparable to regenerating the Amazon rain forest from a fire-scorched desert.

C-Diff shrugs off most antibiotics. Current treatment may include oral doses of Vancomycin -- a drug not absorbed through the digestive tract. But replacing your natural bacteria may be difficult or even impossible, sometimes requiring such radical measures as a "stool transplant" -- having live, warm excrement from another person deposited in your own colon. How is that sinus infection feeling now?

The next time you are prescribed an antibiotic, take a minute to consider the possible consequences. After treatment, eat some live yogurt to give your intestinal bacteria a fighting chance for survival. And in the future -- stay away from doctors!