Every minute of every day, three Americans call a poison control center because they've made a major mistake with their medication.
Some have taken the wrong dose. Some have double-dosed, and others have taken the wrong medicine altogether.
The result: the rate of serious mix-ups has doubled since 2000, a new study reports.
Four out of 10 mistakes involve heart medications, painkillers or hormone therapy prescriptions, including insulin. And the errors often put patients in the hospital, the study found.
"Ever more drugs for ever more diagnoses in ever more people invites ever more error and adverse reactions," said Dr. David Katz, director of the Yale University Prevention Research Center. He was not involved with the study.
The study researchers used U.S. National Poison Data System records to track errors involving prescription or over-the-counter medications taken outside a health care facility. Most of the drugs were taken at home, meaning patients, not health care professionals, made the mistakes.
The rate of serious medication errors rose from 1.09 for every 100,000 Americans in 2000 to 2.28 per 100,000 by 2012. One-third of the cases resulted in a hospital stay, the researchers said.
"Fortunately, most do not result in the serious outcomes found in this study," said lead author Nichole Hodges. She is a research scientist with the Center for Injury Research and Policy at Nationwide Children's Hospital in Columbus, Ohio.
But Hodges said the extent of the problem may be worse than the findings suggest.
"Because this study includes only medication errors reported to poison control centers, it is an underestimate of the true number of serious medication errors in the U.S.," she said. "Unfortunately, we can't tell from the data whether serious medication errors are occurring more frequently, or whether they are simply being reported more often."
Nationwide, at least 1.5 million medication errors occur every year, with poison control centers logging them at a rate of one every 21 seconds.
The study found medication errors outside a medical facility shot up across all age ranges except one: children under age 6.
Among that young group, errors rose between 2000 and 2005, then started to fall. The study pointed to less use of pediatric cough and cold medicines after 2007, when the U.S. Food and Drug Administration advised parents to stop giving those drugs to children.
Most of the errors involved taking the wrong medicine, the wrong dosage or accidentally taking a medication twice.
Two-thirds of deaths in the study involved heart medicines and painkillers combined.
Heart medication mistakes accounted for more than a fifth of errors, while hormone therapy drugs such as insulin accounted for 11 percent.
Painkillers were involved in 12 percent of poisonings, and roughly 80 percent of painkiller mistakes involved products with acetaminophen (such as Tylenol) or an opioid drug.
Hodges said most medication mistakes can be prevented.
"Keeping a written log of when medications are administered can be a helpful strategy for parents and caregivers," she said. "This is especially important if multiple individuals are administering medication to an individual."
Hodges said patients should to talk to their doctor or pharmacist if they have questions about their medicines. Careful storage is also important.
"Individuals who use weekly pill planners should [also] ensure that they are child-resistant and stored up, away and out of sight of children," Hodges added.
Drug makers could help, she noted, by improving drug packaging and labeling. In particular, she said, dosing instructions should be easier for people with limited reading and math skills.
The findings were published July 10 in the journal Clinical Toxicology.