Even as opiate abuse has become a growing problem in the U.S., overdose deaths involving sedatives and antiseizure medications in the benzodiazepine category have also risen steeply, according to a recent study. Prescriptions for benzodiazepines have more than tripled and fatal overdoses have more than quadrupled in the past 20 years, researchers found.

“Overdoses rose at a faster rate than prescriptions, suggesting that people were using benzodiazepines in a riskier way over time,” said lead author Dr. Marcus Bachhuber, assistant professor of medicine at Albert Einstein College of Medicine in New York.

Benzodiazepines typically used to treat anxiety or depression include alprazolam (Xanax), chlordiazepoxide (Librium), diazepam (Valium), and lorazepam (Ativan). The benzodiazepine clonazepam (Klonopin) is used for seizures, while oxazepam (Serax) and temazepam (Restoril) are used for insomnia.

“Benzodiazepines have several known safety risks: in addition to overdose, they are conclusively linked to falls, fractures, motor vehicle accidents, and can lead to misuse and addiction,” Dr. Bachhuber told Reuters Health by email.

The study team used data from the annual Medical Expenditure Panel Surveys between 1996 and 2013, which asked U.S. adults whether they had filled one or more benzodiazepine prescriptions. In those 20 years, the number of adults with benzodiazepine prescriptions grew by more than two thirds, from 8.1 million to 13.5 million, the researchers found. In 1996, around 4 percent of people surveyed had filled a benzodiazepine prescription, and by 2013, this had risen to 5.6 percent.

They also found that the amount of medication distributed had grown by three-fold. After standardizing doses of all drugs, they found that people with prescriptions received 1.4 times more medication in 2013 than 20 years earlier. Benzodiazepines were most often prescribed for anxiety disorders, mood disorders such as depression, and insomnia.

Based on data from the Centers for Disease Control and Prevention, overdose deaths involving benzodiazepines rose from 0.58 per 100,000 people in 1999 to 3.07 per 100,000 in 2013, according to the results in the American Journal of Public Health. This increase seemed to level off after 2010 overall, but among certain groups, including people over age 65 and certain minorities, there was no plateau and the rate kept rising, the study found.

Higher doses, more days of treatment and people combining their prescriptions with illegally obtained benzodiazepines may account for the increase in overdose deaths, the study team writes. Dr. Tae Woo Park told Reuters Health by email that deadly overdoses from benzodiazepines alone are actually rare.