Public health is a tricky, tricky beast. People don’t like being sick, but they also don’t like being told what to do. And in an age of bankruptcy-inducing medical bills, many people just can’t afford to see a doctor. Those three factors combined can lead to a dangerous choice: taking leftover antibiotics at the first sign of a cough or cold. One-quarter of participants in a recent study said they have, or would, self-prescribe antibiotics without getting a diagnosis first. The study results appear in the journal Antimicrobial Agents and Chemotherapy.

The more antibiotics we use, and the more irresponsibly we use them, the closer we push ourselves to an age of completely drug-resistant bacteria, in which today’s common, easily treated infections could once again become lethal.

Yet for all our concerns about the bacterial apocalypse, there’s been very little research into antibiotic misuse in American homes, and the studies that have been conducted focused on immigrants from Latin-American countries. To sample a broader range of people, scientists in Texas surveyed 400 patients in the waiting rooms of three walk-in clinics. Respondents were asked about their antibiotic use in the last year, how they got their antibiotics, and whether they would take, or had taken, the drugs without getting a diagnosis and prescription first.

At first blush, the results seemed promising. Just 5 percent of respondents (20 people) reported self-prescribing antibiotics in the last year. But 25 percent said they would self-prescribe, and 14 percent said they kept a supply of the drugs at home. And those are just people who admitted doing it, the authors say. "Respondents might deny practicing self-medication," they write, "especially if aware that this is inappropriate behavior and if interviewed in a health care setting."

People got their drugs from pharmacies, friends, family members, and in some cases even took their pets' antibiotics. But 74 percent of respondents’ medication stashes were left over from their own unfinished prescriptions.

All of this is bad news for three primary reasons. First, we are prescribed a certain number of antibiotic doses for a reason: to knock out every single bacterium that’s making us sick. You might start to feel better before your prescription runs out, but that doesn’t mean the harmful bacteria are all gone. When you start, but don’t complete, a course of antibiotics, the surviving pathogens are much more likely to become drug-resistant.

Second, unless you have a medical degree, you might very well be misreading your symptoms. A doctor visit and new prescription, when necessary, is the best way to ensure you’re not overlooking something more serious.

Third, antibiotics only work for bacterial infections, not viruses, and most of us don’t know whether our symptoms are being caused by bacteria or a virus. Corresponding author Larissa Grigoryan of Baylor College of Medicine said we’re far too eager to drug ourselves up. “The most common conditions patients reported self-treating with antibiotics were sore throat, runny nose, or cough,” she said in a press statement, “conditions that typically would get better without any antibiotic treatment."

And even if that illness is bacterial, it’s not like the drug your brother’s doctor prescribed for his skin infection can cure your UTI. “Lay people don't know which antibiotics cover which pathogens,” Grigoryan says, "and for how long should they use them."

The bottom line: Ease up on the antibiotics. If you think you have an infection, see a doctor. If that doctor doesn't prescribe you antibiotics, trust that they have a very good reason. (And for Pete’s sake, don’t swipe your dog’s medicine. Come on.)

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