Does the McDonald's Shamrock Shake Turn People's Poop Green?

There’s nothing better than a limited-time menu item, and McDonald’s makes the best of it every year with their classic Shamrock Shake. The classic shake has a unique history. It began circulation in 1970 to celebrate St. Patrick’s Day, but in 1974, it took on a whole new meaning. Former Philadelphia Eagles tight end Fred Hill teamed up with McDonald’s to donate the Shamrock Shake proceeds to Eagles Fly for Leukemia. And now, the shakes are out here making us poop in green!

When the Eagles players approached McDonald’s, they only asked for a portion of the proceeds to build a house near the Children’s Hospital for parents’ lodging while their kids receive leukemia treatment. McDonald’s one-upped them and donated all of the profits, as long as it was named (the now-famous) Ronald McDonald House. The shakes may be good for charity, but they aren't great for our digestive systems! Do the shakes really turn poop green?

If we’ve learned anything from the Bristol Stool Scale, it’s that no poops are created equally! Poop is deeply impacted by everything we eat and drink, and some things are "better" for our bodies than others. Unsurprisingly, a milkshake made by McDonald’s may not agree with our digestive systems. Considering that most of the food from McDonald’s is highly processed, this shouldn’t come as a huge surprise.

At the very least, however, people want to know what’s in the shake that results in the unique green color and flavor. According to a 2016 New York Post article, the Shamrock Shake didn’t gain its minty flavor until 1980. Now the four main ingredients are vanilla soft serve ice cream, Shamrock Shake syrup (which has green food dye, mint flavor, and other chemicals), whipped cream, and a cherry.

A Redditor added, “My first summer job out of high school was working in a factory that made McDonald’s shake flavor syrups. During the process of cooking the Shamrock Shake base, Diethyl Ether is released. We had to wear respirators during production. I took mine off momentarily to wipe the sweat off my face and got pretty high pretty quickly.” Perhaps the chemicals contribute to the green poop.

Now that it’s Shamrock Shake season again, people are sharing their green poop anecdotes. Over the years, the Shamrock Shake has puzzled people and even created a term called the “Shamrock S--t” to describe green poop post-milkshake. While some people are excited, others “did not need to know” that the shake is still in circulation.

Others have pointed out the well-known fact that McDonald’s ice cream machines are almost always broken. “Why does McDonald’s advertise the #ShamrockShake if their ice cream machine is always broken?” Chris Payne tweeted. It’s true! Almost every time we go to get a McDonald’s milkshake, the machine is broken. How can their star seasonal menu item be a milkshake? We just hope they do better this year.