It arrives in a tall cup filled with pebble ice, topped with cream, and often garnished with fruit. But what's inside that glossy cup is anything but clean. Known as the "dirty soda," this concoction combines traditional soft drinks with flavored syrups, creamers, fruit juices and other garnishes. The result is a sweet beverage that blends elements of a soda, mocktail and dessert. And doctors across the country are sounding alarms.

What's really inside that cup

A single dirty soda can deliver between 250 and 400 calories and 55 to 70 grams of sugar per serving. That amount of sugar more than doubles the American Heart Association's daily added sugar limit, according to Erin Palinski-Wade, a New Jersey-based registered dietitian. She told Fox News Digital that the drink "is more like a dessert beverage than a soft drink, even if people use diet soda as the base." The warning extends beyond sugar content. The combination of rapidly absorbed sugar plus cream can cause sharp blood sugar spikes and crashes, driving hunger, fatigue and higher insulin demands.

The danger is greatest for those with insulin resistance, prediabetes or diabetes. The body simply cannot process such a sudden flood of sugar and saturated fat without consequences.

From Utah to the nation

The trend originated in Utah years ago at Swig, a specialty soda shop founded in 2010. Members of the Church of Jesus Christ of Latter-day Saints, who traditionally abstain from alcohol and coffee, embraced the customizable drinks as an alternative. Kelly O'Rourke, marketing director for FiiZ Drinks, a Utah-based soda chain founded in 2014, told Fox News Digital that for many, "It's their version of a coffee ritual." The drinks have since exploded in popularity, fueled by social media and the reality show The Secret Lives of Mormon Wives.

Swig now operates more than 150 locations across 16 states. FiiZ has over 65 locations in more than 10 states, with plans to expand into Connecticut and along the East Coast. Coca-Cola has launched its Coca-Cola Cherry Float, designed to mimic the soda-and-cream experience. PepsiCo now offers Dirty Mountain Dew Cream Soda. McDonald's, Taco Bell, Sonic and Dunkin have all added dirty soda options to their menus. Crumbl recently launched a version that includes multiple sweet ingredients on top of an already sugary soda base.

A metabolic disaster in plain sight

Dr. Mark Hyman wrote in a recent social media post that Crumbl's dirty soda contains 186 grams of sugar, "the equivalent of eating 19 Krispy Kreme donuts." He called it "a metabolic disaster" that "should be illegal." Dr. Marc Siegel, Fox News senior medical analyst, told Fox News Digital the drinks are "very unhealthy," loaded with processed sugar, empty calories and saturated fats. He warned they are "highly addictive, especially because of the high sugar content."