One out of three people with an earache, a sinus infection, or a sore throat is prescribed the wrong antibiotic, according to a study published in late October 2016 in JAMA Internal Medicine.

The findings reveal that U.S. healthcare providers frequently ignore well-established guidelines for antibiotic prescribing from the Infectious Diseases Society of America, the American Academy of Pediatrics, and other major medical organizations.

That means that millions of Americans aren’t getting the safest, most effective treatment for their illness. And misusing antibiotics poses other risks, too, including the spread of superbugs, which are bacteria resistant to the medication.

“We’re talking about inappropriate treatment for some of the most common reasons people go to the doctor,” says the lead author of the study, Adam Hersh, Ph.D., an associate professor in the Division of Pediatric Infectious Disease at the University of Utah in Salt Lake City.

Collectively, ear infections, sinus infections, and sore throats account for more than 40 million antibiotic prescriptions annually.

The Wrong Drug for the Bug

Hersh and colleagues looked at two years' worth of information from the National Ambulatory Medical Care Survey, an annual government survey of patients treated in doctors’ offices, hospital outpatient clinics, and emergency rooms.

They found that instead of prescribing antibiotics targeted to the type of bacteria most likely causing the infection, many doctors were too quick to reach for “broad spectrum” drugs that kill a wider range of bugs.

That’s a problem for several reasons, Hersh says. The wrong antibiotic “may not work as well as the recommended treatment, or, in some cases, carries a much higher risk of serious side effects,” he says.

For example, fluoroquinolone antibiotics such as ciprofloxacin (Cipro and generic) and levofloxacin (Levaquin and generic)—which are frequently prescribed inappropriately for sinus infections in adults—can cause permanent and debilitating damage to muscles, tendons, and nerves.

He also points out that broad-spectrum antibiotics kill more of the body’s protective bacteria, leaving people vulnerable to opportunistic infections from bugs such as Clostridium difficile, or C. diff, which causes a potentially deadly form of diarrhea.

And they are more likely than narrowly targeted drugs to lead to antibiotic resistance.

Why Do Physicians Prescribe the Wrong Antibiotic?

In some cases, healthcare providers have a good reason to choose a different drug. A patient may be allergic to penicillin, for example, or the first drug they tried might not be helping.

But often, the main reason seems to simply be convenience, Hersh says.

For example, the new JAMA study showed that patients frequently are prescribed azithromycin (Z-Pak and generic) or other macrolide antibiotics instead of the recommended first-line treatments, amoxicillin or penicillin.

“Patients tend to favor azithromycin because you typically take it once daily for three to five days,” Hersh says. “Amoxicillin has to be taken two to three times daily for a week.”

But azithromycin's popularity has also been its undoing. “In some areas, as many as 25 percent of the bacteria causing ear infections, sinus infections, and strep throat are now resistant to the drug,” Hersh says.

Get the Right Treatment

If you or a family member has an earache, a sore throat, or a lingering cold, the first question you to ask is not ‘is this the wrong antibiotic?’ but ‘do I need an antibiotic at all?’ says Consumer Reports’ medical director, Orly Avitzur, M.D.

“Most of the time, these infections are caused by a virus, not a bacteria,” Avitzur says. “And antibiotics don’t work against viruses.”

An antibiotic can be appropriate in the following situations:

Earache
Severe pain or symptoms lasting longer than two or three days may be caused by a bacterial infection. Consider antibiotics right away in babies six months and younger or children who are six months to two years old who have moderate to severe pain.

Sinus Pain and Congestion
Consider antibiotics if you don’t get better in 10 days, get better and then worse again, or have a high fever and thick, colored mucus for more than three days in a row.

Sore Throat
Treat with antibiotics only if a throat swab confirms that the symptoms are caused by strep bacteria.

For ear and sinus infections that are probably caused by bacteria, the recommended antibiotic in most cases is amoxicillin (Amoxil and generic) or amoxicillin with clavulanate (Augmentin and generic). For strep throat, the recommended treatment is either amoxicillin or penicillin.

Read more about when you need antibiotics, when you don’t, and how you can feel better without using them.

Editor's Note This article and related materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multistate settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).