(Reuters Health) - Many U.S. adults, including almost half of Hispanics, believe that taking antibiotics will ease the symptoms of a cold, a new study shows - even though most colds are viral and antibiotics don’t work against viruses.

Compared to all Americans on average, Hispanic consumers are almost three times as likely to get antibiotics from a source other than a prescribing physician or to use antibiotics left over from a previous illness, according to a new report from the Centers for Disease Control and Prevention.

Using antibiotics when they won’t work, or using them incorrectly, helps bacteria become resistant, making the drugs less effective when they’re really needed.

“We know from other research that cultural factors can influence health-related knowledge and attitudes,” said lead author Dr. Louise K. Francois Watkins of the CDC.

“However, there have been few national studies looking specifically at knowledge and attitudes regarding antibiotic use among Hispanic consumers, so this study does provide us with new information,” Watkins told Reuters Health by email.

The CDC researchers used data from national Internet surveys collected from participants living in the U.S. in 2012 and 2013, comparing surveys of more than 7,000 U.S. consumers in general to another set of surveys directed at 1,000 Hispanic consumers.

Almost 50 percent of Hispanic consumers believed that antibiotics help a cold get better faster, compared to 25 percent of the general public.

Twenty-five percent of Hispanic respondents said they had used antibiotics left over from a previous illness, and almost as many said they had gotten antibiotics at a neighborhood grocery store, compared to nine percent and five percent of U.S. consumers overall, the researchers reported in the CDC Morbidity and Mortality Weekly Report.

In many other countries, including some in Central and South America, antibiotics do not require a prescription, which may explain why Hispanic people have different beliefs about where to get them and how they should be used, said Dr. William Schaffner of Vanderbilt University School of Medicine in Nashville, Tennessee.

Schaffner was not a part of the new study.

A third survey targeted more than 1,000 health care providers, including 1,001 adult and family physicians, 252 nurse practitioners, and 250 pediatricians.

More than half of providers thought that patients expect an antibiotic at a visit for a cough or cold, when in reality that number is 41 percent of Hispanic consumers and 26 percent of consumers generally.

Pediatricians tend to experience the most pressure to give antibiotics for colds, but teaching middle and high-schoolers about appropriate antibiotic use would help change beliefs over time, Schaffner said in a phone interview.

Antibiotics are appropriate for whooping cough, strep throat or urinary tract infections, but not for bronchitis, flu or other sore throats, according to a CDC infographic.

Antibiotics may cause side effects, allergies or secondary infections, which happen when the drug kills important healthy bacteria in the body.

“For all of these reasons, it is best to see a trained healthcare provider who can help to determine whether an infection requires an antibiotic, and if so, the appropriate type, dose, and duration of treatment,” Watkins said. “Ideally, understanding the health beliefs of different populations is the first step toward creating tailored educational interventions, which may be more effective than a one-size-fits-all approach.”

(Reporting by Kathryn Doyle)