The Ultimate Guide To McDonald's Shamrock Shake

When the January blues clear and the days start to look a little brighter, you know that there's one thing just around the corner. No, folks, it's not spring we're talking about: It's the Shamrock Shake from McDonald's. The chain restaurant's lurid green shake, flavored with a mint syrup and topped with whipped cream, appears on cue each year just before St. Patrick's Day, and is both a way for the fast food joint to honor the holiday and to drive people to its store. Some people love it, some people loathe it, but pretty much everyone has heard of it.

Much like St. Patrick himself, though, the Shamrock Shake is a slightly mysterious concoction. For such a well-known drink, most people aren't aware of its long struggle to get to the status of being available nationwide, and even fewer know about the charitable nature of the beverage. Additionally, its classic mint flavor wasn't even the first choice for McDonald's, and there have been plenty of non-minty shakes throughout the years that have diversified this drink. So, where does the Shamrock Shake come from? How has its recipe developed over the years? Most importantly of all, when and where can you get the darn thing? Here's everything you need to know.

Just like the Big Mac (which was originally created for steel workers) and the Filet-O-Fish, the Shamrock Shake came during a particularly fertile time in McDonald's history: the 1960s. The first Shamrock Shake appeared in 1967, and was the brainchild of a Mr. Hal Rosen. Rosen was a McDonald's operator and owner based in Connecticut, and he originally conceived it with its current role in mind, as a drink that could be bought and consumed to celebrate St. Patrick's Day. Interestingly, Rosen had actually invented the drink the year before this, with a friend called Bridie Flannery. With a background in dairy manufacturing, Rosen was well-placed to tweak the drink until it was just perfect.

Rosen debuted the shake in its minty form, and the word soon got out to the McDonald's higher-ups. Despite this, it took a good few years for the Shamrock Shake to start reaching a wider audience base. The shake didn't start to become available around the U.S. until 1970, when a wider rollout started.

Think of a Shamrock Shake, and you'll likely think of mint. After all, it's been America's most famous minty milkshake for decades, so that's hardly surprising. However, it might be interesting to note that the Shamrock Shake hasn't always been mint-flavored. It certainly was when it was invented by Hal Rosen, who debuted the drink with the minty tones that we associate it with today. When it was rolled out nationally in 1970, though, it underwent a gear shift and was instead prepared with a lemon-lime sherbet, vanilla ice cream, and vanilla syrup.

Kinda different, huh? Well, by 1973 McDonald's realized that things had to change. The restaurant got rid of the lemon-lime sherbet (and with it, we'd imagine, the slightly weird flavor clash that was going on in the drink). However, instead of going back to the mint flavor, they made the Shamrock Shake a simple vanilla milkshake that was tinted green. It stayed like this for a full decade, until 1983 when the bigwigs at McDonald's decided to go back to basics. The Shamrock Shake was mint-flavored again once again, and it would remain that way.

Why is the Shamrock Shake called, well, the Shamrock Shake? The answer lies in the grass. This drink is named after the shamrock, a type of clover which is commonly associated with Ireland, and particularly with St. Patrick. St. Patrick opted to use the three-leaved plant as a way to indicate the Holy Trinity, and it's since become a symbol of St. Patrick's Day — around which the Shamrock Shake is in its highest demand. Interestingly enough, the regular shamrock isn't an indicator of luck, as is commonly assumed; you'll have to find a four-leaf shamrock for that one.

So, the Shamrock Shake's name is unique because as far as we know, it's the only widely-available milkshake that's named after a plant. However, it's also distinctive for a different reason. The Shamrock Shake is the only milkshake available at McDonald's that doesn't indicate its flavor in the name. This was allegedly an intentional choice from Hal Rosen, who liked that it had a mysterious feeling to it. Honestly, Hal, we like it too!

For much of its history, the Shamrock Shake hasn't just been a drink –- it's been something that's allowed McDonald's to fulfil one of its key charitable missions. In 1974, the first Ronald McDonald House was opened in Philadelphia, which has since evolved into a major organization that provides support and accommodation to families who have a sick relative. Ronald McDonald House was first created when a Philadelphia Eagles player's daughter was undergoing leukeamia treatment, with McDonald's founder Ray Kroc and Shamrock Shake inventor Hal Rosen coming together to fundraise and eventually open the house. One of their major avenues for fundraising was through the sales of Shamrock Shakes.

However, the use of Shamrock Shakes to raise money didn't stop there. Sales of the shake now have a baked-in donation to Ronald McDonald House Charities every time you buy one. For each sale of a Shamrock Shake, McDonald's gives 25 cents to the charity. In 2025, McDonald's hopes to raise $5 million from the sales of shakes around the United States, enough to provide 50,000 overnight stays to families in need of help from Ronald McDonald Houses.

On its surface, the Shamrock Shake seems pretty inoffensive. A milkshake that raises money for charity? Honestly, the only controversial thing about it seems to be its mint flavor, which some folks likely hate (not us, though). However, where the Shamrock Shake has messed up somewhat is through its advertising, which has inadvertently caused a bit of stink.

To promote the Shamrock Shake, McDonald's debuted a new character, named Uncle O'Grimacey. This character is (you guessed it!) related to Grimace, the McDonald's mascot that's far more well-known. Uncle O'Grimacey, though, was arguably a bit of a cliche from the offset: The character was presented in shamrock green, and dressed in an Irish cob hat and vest, carrying a shillelagh, a traditional Irish walking stick. As far as cultural representation goes, this was pretty down the line.

However, Uncle O'Grimacey disappeared in the mid-1980s — and the story behind why has been the stuff of legend ever since. The tale goes that the actor who played Uncle O'Grimacey made comments in support of the Irish Republican Army, leading to the mascot's hasty removal. This story seems to be false, and may instead stem from a satirical article published in The Onion in 1997, but that hasn't stopped people from believing it. Incredibly, though, that wasn't the last that people saw of Uncle O'Grimacey. As of 2025, he's back in town to promote Shamrock Shakes. 

Anyone who's set eyes on a Shamrock Shake before will likely have a sense that it's not the healthiest thing in the world. Sure, it's green, but it's not the type of green that screams health (it's more like the type of green that screams, well, excessive use of food dye). So it's little surprise that what's really in a Shamrock Shake isn't exactly healthy for you. A large serving of the Shamrock Shake has a whopping 84 grams of added sugar, approximately 168% of your daily value. In total, it has 135 grams of carbohydrates, which is roughly the same amount as 2 cups of dried spaghetti – and yet, there's no fiber to be seen anywhere in this drink.

To add to this, a large Shamrock Shake provides you with 13 grams of saturated fat, or 64% of your daily value, and 20 grams of total fat. This is despite both the ice cream and the whipped cream used being lower-fat versions. In the ingredients list, you'll spot a collection of additions that are far from pleasing: High fructose corn syrup, regular corn syrup, sugar, and various food colorings all make the cut. If you're at all concerned about your dietary intake of any of these nutrients or ingredients, we'd give the Shamrock Shake a wide berth.

Shamrock Shakes haven't always been in liquid form. Back in 1980, McDonald's capitalized on the success of its milkshake with an ice cream touting its flavors. The Shamrock Sundae was introduced for a limited time, and consisted of the restaurant's famous soft-serve ice cream topped with a Shamrock syrup — which, as you probably figured out, was bright green and mint-flavored. Although this seems like a pretty innocuous addition to the McDonald's lineup, the sundae only lasted for a year before it was discontinued for good.

However, that hasn't stopped McDonald's from trying out new forms of the Shamrock Shake, once again featuring ice cream. In 2025, McDonald's introduced the Oreo Shamrock McFlurryat the same time that the Shamrock Shake reappeared in stores. This McFlurry sounds a lot like the original sundae, and is made up of a combo of soft serve and Shamrock syrup mixed together. The twist, though, is the addition of crumbled Oreo pieces also mixed through it all. We've gotta admit, this one sounds slightly more interesting than the original Shamrock Sundae; consider us intrigued.

Although the Shamrock Shake went through a few different flavors in its early life, it eventually settled on its classic mint flavor, and has stayed tasting fresh ever since. However, that doesn't mean that it hasn't had a few different spins on its recipe since then. In 2017, McDonald's rolled out a few variations on its Shamrock Shake that took advantage of the immortal flavor combo of mint and chocolate. At the top of the pile was its Shamrock Chocolate Chip Frappé, which infused the flavor of a regular chocolate frappé with peppermint and topped it with some whipped cream and chocolate and caramel sauces.

McDonald's also debuted a Chocolate Shamrock Shake, with the bottom half consisting of a chocolate milkshake and the top half tasting of mint. It also rolled out a Shamrock Hot Chocolate and a Shamrock Mocha. These flavors were apparently inspired by McDonald's infamous secret menu orders, with the restaurant clearly paying attention to the alterations customers were making to its shakes and responding accordingly. McDonald's even decided to revamp its straws for this rollout of new Shamrock Shake flavors, with a limited-edition straw design that allegedly distributed the flavors of each shake more capably.

McDonald's has a habit of holding back some of its regional menu items and forcing customers to travel to try them, but surely that wasn't the case with the Shamrock Shake, right? Surely, surely, this ultra-famous shake was always available anywhere you went? Nope -– and it became available nationwide way later than you might think. Shamrock Shakes only started being available around the country in 2012, a full 45 years after it debuted in Connecticut. Before that, you'd have found it in areas that had notable Irish-American communities, but you'd be out of luck at your neighborhood McDonald's.

Shamrock Shakes, like so many McDonald's items, were previously put on menus on a case-by-case basis. It was basically left up to local market operators to decide whether there would be enough demand to justify stocking the shake in their stores. Interestingly, this inadvertently led to a larger demand for the item as it reached cult-like status, which then likely prompted its national availability. Plus, when the Shamrock Shake went national, it went through one more change: It gained the now-customary dollop of whipped cream that goes on every milkshake.

Large Shamrock Shakes are pretty big, but it's fair to say that they're not overly notable. Back in 2010, though, a Shamrock Shake was created that was so big that it'd give Godzilla a run for its money. To celebrate St. Patrick's Day in Chicago, McDonald's created the "World's Largest Shamrock Shake," which came in at 24 feet tall. McDonald's then staged the shake to look as though it was pouring into the Chicago River.

If this conjures up pictures of the bright green shake polluting the waterways, never fear. No liquid was actually poured into the river itself, and instead the shake was a solid construction that merely looked as though it was flowing out. So what was the point of doing all this in the first place? Well, apart from acting as good publicity for the Shamrock Shake itself, the stunt was performed in honor of a sizable donation to a Chicago-based Ronald McDonald House. The massive shake brought attention to the drink's association with charitable donations, which doubtless caused more people to buy it — resulting in more money for the organization.

The Shamrock Shake started being available nationally in 2012, but before then, there were a lot of people who wanted to try it — and they were willing to put in the work. Therefore, these shakes became somewhat of a cult item that folks attempted to hunt down each year. People would flock to online forums to trade tips about where Shamrock Shakes could be found, and which areas were lacking in stock. Some individuals resorted to making a dedicated website that detailed the stores around the country that sold Shamrock Shakes.

Then, in 2018, McDonald's got in on the fun. The restaurant debuted its McDonald's Finder app, which gave customers the ability to see which stores had Shamrock Shakes and which didn't. This seems kinda redundant, given that by this point Shamrock Shakes were readily available pretty much everywhere. We're sure it resulted in some great press for McDonald's, though — and isn't that what it's all about?

Despite being clearly inspired by Ireland and associated with St. Patrick's Day, the Shamrock Shake is an American McDonald's item, through and through. Some might argue that international McDonald's menus are way better, but none of them had the bright green, minty shake. Well, until recently, that is. Nowadays, you can find the Shamrock Shake in some other countries, although it's notable that it's only available in English-speaking nations.

As of 2025, the Shamrock Shake has been (and is) available in Canada, the United Kingdom, and Ireland. As in the U.S., you can only find them in these countries around St. Patrick's Day, and they have a fairly limited window of availability. It's unclear exactly why the shake is only stocked in these countries and not in others. Perhaps it's because these are the nations whose McDonald's menus have the closest similarity to the one in the USA, or maybe it's because they have stronger cultural associations to St. Patrick's Day than other places around the world (especially in Ireland, of course).

No breakdown of the Shamrock Shake would be complete without discussing when you can actually get the darn thing. We all know that it only appears around St. Patrick's Day on March 17, but what a lot of people don't realize is that its rollout starts way before the day itself. McDonald's is pretty vague on its site when it comes to exact dates, mentioning that it "magically appears once a year, usually in March." We can do better than that, right?

Yep. We're here to tell you that the Shamrock Shake is now available in participating stores in the United States. It's worth mentioning that some stores may roll it out slightly later than this. You can generally expect to see it removed from menus pretty much immediately after St. Patrick's Day, so get it while you can. In other countries like the UK you may have slightly less time, as the Shamrock Shake will only be available there until Tuesday, March 25.