A growing number of people are taking high doses of the painkiller acetaminophen, and many take so much during cold and flu season that they risk liver and kidney damage, two studies suggest. A study of 14,481 U.S. adults found that 6.3% of acetaminophen users exceeded the maximum recommended daily dose at least one day during weeks when they used the drug. During cold and flu season, people were 24% more likely to exceed the 4,000-milligram recommended maximum at least once a week.

Acetaminophen, sold as paracetamol in Europe, can ease a fever, but many people may take too much out of a mistaken belief that it will also cure the flu, said Dr. Liffert Vogt, a researcher at the University of Amsterdam Academic Medical Center in the Netherlands who wasn’t involved in the study. “I would not recommend taking acetaminophen for cold and flu symptoms,” Vogt said by email. “Taking a cup of soup will be much more efficacious than taking a pill.”

In the U.S. study, the proportion taking too much wasn’t large—6.5% during cold and flu season compared with 5.3% at other times of year—but because millions of adults use the drug, the seasonal increase adds a substantial population-level risk, the authors note. Taking too much acetaminophen (Tylenol) can cause liver and kidney damage, especially at high doses and with long-term use, Vogt said. While the risk is lower with acetaminophen than with other painkillers such as ibuprofen (Motrin) or other nonsteroidal anti-inflammatory drugs (NSAIDs) like naproxen (Aleve), all of these medications can cause harm when taken in excess. Patients need to read labels carefully to ensure that the remedies they use for cold and flu symptoms do not contain more than the maximum recommended doses of acetaminophen or other painkillers. "Getting this message out is especially important during cold and flu season, when people may be more likely to treat symptoms with acetaminophen combination products, sometimes without even realizing they contain acetaminophen," lead study author Dr. Saul Shiffman of Pinney Associates and the University of Pittsburgh said in a statement. The problem of acetaminophen overuse is not limited to the U.S.; a second study of painkiller use in France from 2006 to 2015 found that country to be the largest user of acetaminophen in Europe, and it ranked third for use of mild opioids. During the study period, acetaminophen use in France surged 53%, and 1,000-milligram tablets have been the most commonly used preparation among adults there since 2008. Use of high-dose pills more than doubled during the 10-year study period, while use of 500-milligram tablets declined by 20 percent. Both studies were published in the British Journal of Clinical Pharmacology. Neither examined rates of health problems associated with acetaminophen overdose or why usage increases seasonally or over time. Another limitation is that researchers could not distinguish medically necessary use from substance use problems or accidental overuse. “This extensive consumption of analgesics that we have documented raises concerns about overuse and misuse, as well as about opioid addiction,” said Karima Hider-Mlynarz, lead author of the French study at the French National Agency for Medicines and Health Products Safety in Saint-Denis. “Even when prescribed and widely used, none of these analgesics are harmless, and doses must always be respected,” Hider-Mlynarz said by email. Source: British Journal of Clinical Pharmacology, online March 7 and March 25, 2018.