Scientists discover a link between certain antidepressants and superbugs

Superbugs are pretty much just as terrifying as they sound. Over time, these strains of bacteria have become resistant to antibiotics, making them incredibly hard to kill even with the most reliable, commonly used treatments. And according to new research, one of the most widely prescribed antidepressants could be contributing to the problem.

Fluoxetine—better known by its brand names: Prozac, Sarafem, and more—is a selective serotonin reuptake inhibitor (SSRI) used to treat depression, obsessive-compulsive disorder, eating disorders, and other mental health conditions. In a new study published in the journal Environment International, researchers exposed the popular antidepressant to E. coli bacteria (something that often comes from contaminated food or water), which caused mutations in the bacteria. In fact, the higher the exposure to the drug, the faster the mutations occurred.

Unfortunately, those mutations became resistant to three different antibiotics—chloramphenicol, amoxicillin, and tetracycline—typically used to treat serious bacterial infections. “This discovery provides strong evidence that fluoxetine directly causes multi-antibiotic resistance via genetic mutation,” lead study author Jianhua Guo, PhD, said in a statement.

“This discovery provides strong evidence that fluoxetine directly causes multi-antibiotic resistance via genetic mutation.” —Jianhua Guo, PhD

Researchers think fluoxetine could potentially cause antibiotic resistance inside the gut, but the overall impact could be bigger than that. After it’s taken orally, 11 percent of the drug passes through the body totally unaltered—and because the remainder ends up in the sewer system after its exited the body through the urine, it could increase antibiotic resistance on a larger scale. “Fluoxetine is a very persistent and well-documented drug in the wider environment, where strong environmental levels can induce multi-drug resistance,” he says.

So what does all of this mean? Since previous research has shown 1 in 10 people in the United States take SSRIs and Prozac is one of the most popular options, that’s a lot of fluoxetine that could potentially be causing antibiotic resistance both inside the body and in the environment. Right now, 700,000 people a year are dying from infections from superbugs—and that number is predicted to reach 10 million by 2050 if action isn’t taken, mostly due to the overuse and misuse of antibiotics. Luckily, scientists are working hard to solve the problem, even using essential oil to kill off some of the toughest strains—so let’s hope there will be effective solutions soon.

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