Lots of us depend on coffee as a morning pick-me-up, but some folks on social media are reporting that Starbucks’s new product line is waking up their bodies a little too much. 

In February, Starbucks launched a range of drinks in Italy called Oleato, which combines coffee with olive oil. The Oleato line includes three flavors: Oleato Golden Foam Cold Brew, Oleato Caffé Latte, and Oleato Iced Shaken Espresso. All of the beverages arrived in the US on March 23 in Chicago, Seattle, and New York City. 

Each beverage is doused with Partanna extra virgin olive oil. As Starbucks describes it, this gives your drink a “sweet and lush” flavor and makes it “velvety smooth.”

But, it turns out that it might be a little too smooth. After the drinks launched, some people who tried them took to social media to describe an unintended side effect: prompt races to the bathroom. Reddit users reported bowel problems, stomachaches, diarrhea, and, in some extreme cases, vomiting. 

So what’s behind that? To start, there’s a good amount of caffeine in these beverages. For example, a grande drink in the line ranges from 170 mg to 255 mg of caffeine. (For reference, one serving of a Monster energy drink contains about 79 mg, with the entire 16-oz can coming in at 158 mg.)

Because it’s coffee, that part isn’t surprising. The fat content, however, is another story. The amount of fat ranges from 17 g to 34 g in a singular grande cup in the Oleato line. Compare that to 0 g in a grande cup of plain coffee or 7 g in a regular grande latte with 2% milk. (One tablespoon of olive oil contains 14 g fat.)

Of course, fat is an essential nutrient and adds plenty of flavor to your food. When you eat fat as part of your meals, it slows the digestion process, which helps boost satiety and keeps you feeling full longer, as SELF reported previously. But if you take in too much of it too quickly, especially on an empty stomach in the morning—like many folks do with their coffee—fat can “exacerbate the urgency to run to the bathroom,” Brigitte Zeitlin, MPH, RD, CDN, tells SELF. Fats like olive oil can stimulate motility in the colon and “help smooth the insides of the bowel, making it easier for stools to pass through,” explains Zeitlin. 

That, combined with the coffee, can really get your GI system working. That’s because caffeine also stimulates gut contractions, Rabia De Latour, MD, a gastroenterologist and assistant professor at the NYU Grossman School of Medicine, tells SELF. (This may be why some people find themselves running to the bathroom after their first cup of coffee in the morning, even when there’s no olive oil involved.) 

Coffee also contains acid, which boosts a hormone made in the stomach called gastrin, says Dr. De Latour. Gastrin stimulates a muscle contraction that moves waste along in the GI tract; high levels of this hormone could lead to diarrhea. Add olive oil to the mix, and it’s no surprise that things can get extra active.