Enlarge By Joe Raedle, Getty Images Doctors are emphasizing the downside of antibiotics to dissuade patients from requesting them unnecessarily. 'GOOD' MICROBES GET MASSACRED 'GOOD' MICROBES GET MASSACRED Here's one more reason not to take an antibiotic you don't need: The millions of microbes that inhabit your gut won't like it. In a recent study at the Stanford University School of Medicine, researchers counted the types and numbers of bacteria that inhabited the bowels of healthy volunteers before and after treatment with an antibiotic. None of the three volunteers developed diarrhea or other bowel symptoms, says researcher David Relman. But one-third of the bacterial species in their guts suffered major population losses. Numbers were back to normal within a month. But these microbes are thought to have important jobs -- including protecting us from disease-causing invaders -- so avoiding such massacres whenever possible seems a good idea, Relman says. DAILY HEALTH BLOG DAILY HEALTH BLOG Get wellness tips, medical study roundups and news for healthy living here, including info on ... • Fitness and nutrition

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• Watercooler-worthy bits HAVE A HEALTH OR MEDICAL QUESTION? HAVE A HEALTH OR MEDICAL QUESTION? E-mail kpainter@usatoday.com. Please include your name, city and daytime phone number. Selected questions will be answered in the paper and online. Would you beg your doctor for drugs that: •Have a 5% to 25% chance of causing diarrhea? •Land at least one in every 1,000 users in the emergency room? •Help only about one in 4,000 patients avoid a serious complication? •Do nothing to relieve your symptoms? If you've answered no, congratulations: You've decided to stop demanding antibiotics for colds, flu and similar illnesses. And you've demonstrated what some doctors suspect: The best way to break patients of their dangerous, expensive addiction to unneeded antibiotics is to focus on the personal risks and benefits — which are becoming clearer, thanks to recent research. The message, in a nutshell: "There's a very small chance this antibiotic will help you, but a much bigger risk that it will hurt you," says Jeffrey Linder, an assistant professor at Harvard Medical School and Boston's Brigham and Women's Hospital. Health educators have struggled to convince the public that antibiotics are useless for colds, influenza, most sore throats and the vast majority of bronchitis cases. That's because those illnesses are caused by viruses. Antibiotics kill only bacteria. They've also told people that every time they take unneeded antibiotics, they encourage the growth of bacterial strains that resist antibiotics and can spread through households and communities, creating hard-to-control "superbugs." Result: "We're not getting anywhere," Linder says. Half of antibiotic prescriptions still go to people with viral illnesses. Many doctors believe antibiotics satisfy these patients, prevent some complications and do little or no harm, he says. Allergic reaction a real threat But recent studies that quantify risks and benefits might give these doctors pause — and the ammunition they need to resist patients' pleas. In one study, researchers from the Centers for Disease Control and Prevention found that one in every 1,000 patients who got antibiotics during a doctor's visit landed in an emergency room with an allergic reaction or other problem caused by the antibiotic. That's more than many experts expected and translates into 142,505 emergency room visits a year, says CDC researcher Daniel Budnitz. That number doesn't include people who just called their doctor to report a rash or suffered silently with antibiotic-induced diarrhea (which happens in up to 25% of cases, depending on the drug). Meanwhile, British researchers found that doctors would have to give antibiotics to 4,000 cold sufferers to prevent one case of bacterial pneumonia, a report in the British Medical Journal says Budnitz says the CDC is updating its antibiotic education campaign to put more emphasis on personal risks. Antibiotics are wonder drugs for certain conditions, but they "are not harmless," he says. So it makes no sense to use them when there are "uncertain, if any, benefits." But William Hueston, chair of the department of family medicine at the Medical University of South Carolina, isn't sure patients want or need to hear more antibiotic statistics. "Patients just want to feel better," he says. Doctors who help patients ease symptoms with pain relievers, inhaled drugs that work against cough, and other measures can avoid the antibiotic argument altogether, he says. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more