A Mayo Clinic study finds that nearly 70 percent of Americans are prescribed at least one medication, with antibiotics, antidepressants, and opioids topping the list.

Nearly seven out of 10 Americans were prescribed at least one drug in 2009, and half were given two or more, according to new research from the Mayo Clinic.

The most commonly prescribed drugs were antibiotics, antidepressants, and painkilling opioids, according to the study, published this week in the journal Mayo Clinic Proceedings.

Study author Dr. Jennifer St. Sauver said that women and older adults received more prescriptions, but prescription drug use spanned all age groups. Children were most commonly prescribed anti-asthma medications, antibiotics, and vaccines.

“When people talk about the most common chronic conditions in the community, they’re talking about things like heart disease and diabetes. Well, the second most common prescription in our community is for antidepressants, so that does suggest that mental health conditions are a huge issue in our community and maybe an area we should focus on,” she said in a YouTube video explaining the research.

The community, specifically, is Olmsted County, Minn. (pop. 142,377), which is the site of the Mayo Clinic’s Rochester Epidemiology Project, a large-scale population study. Researchers there say the makeup of the population is comparable to that of the rest of the country.

While the researchers couldn’t definitively say why so many people take prescription medications, there are several reasons why spending on prescription drugs in the U.S. reached $250 billion in 2009, the year prescription use was analyzed.

Antibiotic resistance is a major concern and one of the U.S. Centers for Disease Control and Prevention’s (CDC) top priorities. Bacteria have learned to evolve in response to antibiotics, making them ineffective against some bacterial strains, and drug companies are unable to keep up with their evolution.

As early as the 1970s, doctors were prescribing antibiotics to treat the common cold, which did nothing to help because colds are caused by viruses, not bacteria.

The Mayo Clinic recommends using antibiotics only for major infections, such as infections of the bladder or skin, strep throat, some ear infections, and severe sinus infections that last longer than two weeks.

The overuse of antibiotics—especially the 14,440 tons used annually in livestock—is the topic of a bill presented by U.S. Rep. Louise Slaughter (D-NY). Introduced for the third time this March, the Preservation of Antibiotics for Medical Treatment Act hopes to reign in the overuse of antibiotics in humans and animals. The bill continues to lay dormant before the House subcommittee on health.

An estimated one in four Americans will experience a mental health disorder, such as depression or anxiety, in a given year, according to the National Alliance on Mental Illness.

Typical first-line treatments for mental health issues are medication and some type of psychotherapy.

Critics who say antidepressant medications are overused often claim there is a chicken-and-egg phenomenon, saying that antidepressants are prescribed for normal human reactions to life events, leading to a lasting diagnosis of mental illness.

However, as the public mindset continues to change, there’s now less stigma attached to getting help for mental disorders, which may help explain the rise in antidepressant use.

Earlier this month, Pres. Barack Obama said his administration plans to “bring mental health out of the shadows” by increasing the money and attention given to mental health services in the country.

Opioids are a class of drugs known for their ability to produce a euphoric high, as well a debilitating addiction. They are strictly regulated for these reasons and should only be prescribed to treat chronic pain resulting from a disease, surgery, or injury, according to the Center for Addiction and Mental Health.

Opioids—codeine, oxycodone, and hydrocodone—are increasingly popular recreational drugs that have been both celebrated and condemned in popular culture.

There is a high potential for fatal opioid overdoses, made evident by the fact that 60 percent of the 38,329 people who died of a drug overdose in the U.S. in 2010—including comedian Greg Giraldo—died taking prescription drugs. Three out of four of those deaths were caused by opioid analgesics, according to CDC estimates.