The fact is, antibiotics can cure bacterial infections but are ineffective against viruses — and viruses, not bacteria, cause the common cold, most coughs and the flu.

Yet some patients, who may have received antibiotics in the past for colds and other viral illnesses, show up at the doctor's office expecting them, says Dr. Alexis Karageorge, a Louisville internist.

In her experience, the most commonly requested antibiotic is the Z-Pack, which has been very overused, she says.

The Z-Pack is the antibiotic called azithromycin (brand name: Zithromax) — a highly popular and highly potent antibiotic meant to cure bacterial infections of the throat, sinuses and respiratory tract.

But it won't cure your cold or flu or keep others from catching your viral illness, health experts say.

While you may think you feel better, it could be you're just getting over your illness or you're enjoying the "placebo effect from receiving an antibiotic," says Glenn L. Watson, director of pharmacy services for Jewish Hospital in Louisville, Ky.

You may not believe that your misuse of antibiotics puts you in jeopardy or causes other people problems.

However, because we harbor lots of bacteria in our bodies all the time, inappropriate use of antibiotics can kill some germs while others survive the assault of the antibiotic and adapt into drug-resistant "super bugs."

Antibiotic use not only creates more drug-resistant bacteria in you, which may be a problem for you later on, but the resistant bacteria also can spread to others.

We end up with new strains of bacteria that are more difficult and expensive to treat, that make patients sicker, that require more hospitalizations and that even turn lethal.

Shahriar Mobashery, a University of Notre Dame bioorganic chemist, said in a university publication that in the next 10 to 20 years all eight broad classes of antibiotics will become obsolete.

While he and his research team are working on a new class of antibiotic drugs to fight bacterial infections, he said it will take a lot of money and time to get new drugs to patients.

Dr. Richard Besser, medical director of the CDC's Get Smart: Know When Antibiotics Work campaign, says there is evidence that curbing antibiotic use can improve the picture.

The Get Smart campaign has been reaching into some communities for several years, and physicians' and nurses' groups have worked to curb antibiotic use.

"We have begun to see declines in pneumococcal resistance. This makes it essential that we use antibiotics appropriately so as not to cause a resurgence in antibiotic resistance," Besser says.