Bitters are one of those quiet essentials in cocktail making — small in quantity, huge in impact. A few drops can completely transform a drink, turning something simple into something layered, balanced and far more expressive. They work the same way seasoning does in cooking: you don’t always notice the bitters themselves, but you notice the difference when they’re missing.

For whisky cocktails in particular, bitters help bring depth, lift or clarity to a serve, depending on the style of dram you’re using. They can brighten citrus, amplify spice, soften sweetness or underline the character of the whisky itself.

This guide breaks down what bitters are, how they’re used, and which classic serves showcase them beautifully — including a few favourites from The Glenlivet. Let’s explore why bitters deserve a place in every cocktail lover’s cupboard.

Bitters are highly concentrated botanical infusions made by steeping herbs, spices, citrus peels, roots or flowers in high-proof alcohol. The result is a potent, aromatic liquid measured in dashes rather than pours.

Originally crafted as medicinal tonics, bitters eventually became a cornerstone of cocktail making — especially in whisky serves — because of how effectively they bring balance, depth and complexity. They add structure to a drink, anchoring certain flavours while lifting others, all without overwhelming the whisky itself.

Most bitters fall into the “aromatic” or “citrus” families, though the modern landscape includes chocolate, cherry, cardamom, walnut and more. Each style brings its own character, making bitters one of the easiest ways to tailor a cocktail to your taste.

Classic, warming and full of spice, aromatic bitters are the backbone of many whisky cocktails. They typically include gentian root, herbs and baking spices, giving them a rounded, slightly savoury flavour profile.

You’ll find them in the cocktail world’s most famous serves — including the Old Fashioned, where they add depth and balance to the whisky.

Bright, zesty and highly fragrant, orange bitters add citrus lift without introducing sweetness. They’re brilliant in gin-based drinks, but also work beautifully in whisky cocktails when you want to emphasise fresher, lighter notes.

This broad category includes everything from chocolate and cherry to walnut, coffee and celery. Flavoured bitters help shape a drink’s personality without altering its basic structure — perfect for modern twists or personalising a classic.

They’re also a great way to echo a whisky’s existing characteristics, such as pairing chocolate bitters with an oakier dram or cherry bitters with cocktails that use fortified wines.

Bitters are powerful, so they’re added in dashes, not pours. Because they’re so concentrated, even one extra dash can noticeably shift the feel of a drink. Here’s how to use them confidently:

–  Add gradually – Start with the suggested amount and adjust to taste.

–  Think of them as seasoning – Bitters bring flavours together and soften sharper edges.

–  Match the style to the serve – Citrus bitters brighten, aromatic bitters deepen.

–  Remember aroma matters – A dash on top changes the nose of a cocktail instantly.

–  Try them in stirred and shaken drinks – They work just as well in refreshing highballs as in slow-sipping classics.

Bitters are an effortless way to make a drink feel more polished — even the simplest recipe becomes more refined with a thoughtful dash.

One of the most rewarding ways to experiment with bitters is to create a custom blend. Instead of relying on a single bottle, bartenders often mix bitters styles to create a more nuanced profile.

The Glenlivet uses this technique in our Ultimate Old Fashioned, which calls for a “perfect bitters blend” made by combining different bitters to achieve a balanced, carefully layered flavour.

It’s a simple approach you can recreate at home:

–  Combine two aromatic bitters for structure

–  Add orange bitters for brightness

–  Experiment with a flavoured bitters (cherry, chocolate, cardamom) to complement the whisky’s character

The goal isn’t intensity — it’s harmony. Blending bitters allows you to highlight specific qualities in The Glenlivet, whether you want more fruit, more spice or a smoother finish. It’s an easy way to add personality and craftsmanship to your cocktails.

Here are three classic cocktails that show exactly how bitters can elevate a drink.

The Old Fashioned is the definitive example of bitters at work. A couple of dashes frame the whisky’s natural sweetness, providing structure while keeping everything balanced.

Made with The Glenlivet 12 Year Old, the drink becomes smooth, modern and wonderfully expressive — ideal for a slow evening or a post-dinner digestif.

Rich, layered and deeply aromatic, the Vieux Carré uses two types of bitters to create its signature complexity. Aromatic bitters give warmth and spice, while Peychaud’s-style bitters add gentle floral lift.

It’s a drink for evenings that deserve something elegant and contemplative — best served with music, candlelight or a relaxed conversation that lingers.

In our Scotch and honey cocktail, bitters bring balance to its natural sweetness. They add subtle contrast, lifting the whisky without interrupting its smooth, rounded style.

It works beautifully for early-evening hosting or relaxed weekends, especially when paired with light snacks or citrus-led dishes.

Whether you’re mixing classics or creating your own blends, bitters offer endless opportunity for exploration. And if you like things on the less sweeter side, don’t miss our guide to bitter whisky cocktails.

Whether you’re making your first Old Fashioned or experimenting with your own cocktail recipes, bitters are one of the easiest ways to elevate a drink. A single bottle of aromatic bitters can transform dozens of whisky cocktails, while orange and flavoured bitters open up even more creative possibilities.

If you enjoy more spirit-forward serves, explore our guide to bitter whisky cocktails or learn more about the cocktail making world in our guides to when to shake and when to stir, how to use egg white in cocktails and the best whiskies to use.