Straight Answers About Antibiotics WebMD Sponsor: Humana People consume about 235 million doses of antibiotics annually, according to the Centers for Disease Control and Prevention (CDC) in Atlanta. The CDC estimates that 20 percent to 50 percent of these are unnecessary. Here's what you need to know so you can use antibiotics wisely: Q. What germs do antibiotics kill? A. Antibiotics are designed to kill bacteria. They can be an effective treatment for bacterial infections, including a sinus infection, strep throat, ear infection or bacterial pneumonia. Most antibiotics must be prescribed by a doctor. Q. Should I take an antibiotic to treat a cold? A. No. Colds are caused by viruses, not bacteria. It's important not to take antibiotics for a viral infection because the antibiotics will attack any existing bacteria in your body. (Your body normally hosts bacteria, even when you are well.) If you take an antibiotic when you have a viral infection, some of the bacteria will be killed, but some can survive. Any surviving bacteria learn to adapt to resist the antibiotics. The result are so-called "supergerms." These germs can lead to more serious illnesses in the future that require stronger medications. Q. How do I know if I have a cold or a sinus infection? A. Symptoms of a cold include a sore throat, runny nose, congestion, sneezing, nighttime coughing and possibly a headache. Symptoms of a sinus infection (which may follow a cold) are more severe. You could have a fever return several days into the cold. You could also have a cough and thick congestion that lasts more than a week. Q. What are the most important things to remember when taking an antibiotic? A. Take all of an antibiotic exactly as prescribed. If you stop taking it because you feel better, you could leave behind future supergerms. Antibiotics don't have to do all the work--you can help avoid passing germs on to others by washing your hands often. Do You Need Antibiotics? Antibiotics should only be used to treat bacterial infections. Here's a quick look at the types of infections antibiotics can and cannot help. TREATABLE: * Sinus Infection * Strep Throat * Bacterial Pneumonia NOT TREATABLE: * Cold * Sore Throat * Bronchitis (usually viral) From WebMD