United States

Boston Sour

Also known as Whiskey Sour with Egg White, Boston Club Sour

A Boston Sour is just a Whiskey Sour with an egg white shaken in, giving it a rich, silky cap of foam.

whiskeycitrussourfoamyegg whitebourbonclassicsilkytart

ABV

Difficulty

Overview

What this drink is like

The first sip hits you with that soft, frothy foam before the sharp whiskey and citrus cut through. The middle is a balance of sweet and sour, and the finish leaves a lingering warmth from the bourbon with a clean, lemony fade.

Who will like it

For people who like the bite of a Whiskey Sour but want a smoother, creamier mouthfeel without adding dairy.

When to drink

This is a great early evening drink to kick off a night out, or a solid brunch cocktail if you want something with a little backbone.

Ordering tip

If you want a stiffer, spicier drink, ask your bartender to swap the default bourbon for rye whiskey.

Ice: NoneTemp: ColdCost: $2–$4Glass: CoupeHome bar friendly

Flavor

Taste profile

This drink takes the sharp, refreshing bite of a whiskey sour and softens the edges with a thick layer of egg white foam. You get the warming kick of bourbon right away, followed by a tart lemon squeeze that is smoothed out by the creamy texture. It is not a heavy drink, but it coats your mouth in a way a regular sour does not. The finish is clean with just a hint of spice from the whiskey.

Finish: The finish is medium-long, leaving a warm bourbon glow and a lingering tartness that fades into a clean, slightly sweet mouthfeel.

Primary tastes

soursweetcreamy

Secondary

fruityearthy

Aroma

citrus oilbaking spiceoak

Bitternesslow bitterness
Just a touch from the bitters and the char of the bourbon.
Sweetnessbalanced sweetness
The syrup balances the lemon juice without making the drink sugary.
Sournessmoderately sour
The lemon juice is front and center, cutting through the rich egg white.
Strengthmoderately strong
The bourbon stands up to the citrus and syrup, keeping the drink spirit-forward.
Refreshingmoderately refreshing
The cold citrus makes it refreshing, but the egg white adds weight.
Creaminessfairly creamy
The dry-shaken egg white creates a thick, silky foam that changes the whole texture.
Complexitymoderately complex
The texture adds a layer of interest to an otherwise straightforward sour.

Recipe

Make it at home

Shaken · Coupe · equal parts on Bourbon Whiskey. A decent mid-shelf bourbon works best; rye is a good spicier alternative

Before you start

Chill your coupe glass in the freezer for a few minutes if you have time, and make sure your egg is fresh.

Ingredients

Bourbon WhiskeyBase Spirit60ml
Fresh Lemon JuiceJuice30ml
Simple SyrupSyrup20ml
Egg WhiteDairyFrom a large egg; must be fresh1 egg white
Angostura BittersoptionalBittersFor aroma and dotting the foam2 dashes
Lemon PeelGarnish1 twist

Garnish: Lemon twist, Angostura bitters dots on foam

Tools

Cocktail Shaker · Shaking
To emulsify the egg white and chill the drink
At home: A large mason jar with a tight lid
Hawthorne Strainer · Straining
To catch the ice while pouring the liquid and foam into the glass
At home: A fine mesh sieve
Jigger · Measuring
To measure the whiskey, juice, and syrup accurately
At home: A measuring spoon or small shot glass
Coupe Glass · Serving
To serve the drink and show off the foam cap
At home: Any stemmed wine glass

Steps

1
Add the bourbon, lemon juice, simple syrup, and egg white to your shaker without any ice. Seal it tight and shake hard for about 10 seconds until you feel the shaker get slightly warm and the mixture inside looks thick and frothy.
~10s
!Skipping the dry shake leaves you with thin, watery foam.
2
Open the shaker, fill it to the top with ice, and seal it again. Shake hard for another 10 to 12 seconds. You will know you are done when the outside of the shaker feels frosty and almost too cold to hold.
~12s
!Shaking too softly will not chill the drink enough or whip the foam properly.
3
Pop the shaker open and fit your Hawthorne strainer over the top. Pour the drink into your chilled coupe glass, letting the foam pour out last so it sits on top of the liquid like a thick cap.
!Pouring too fast can break the foam and leave air bubbles.
4
Take your lemon peel, hold it over the drink, and give it a good pinch to spray the citrus oils across the foam. Drop the peel in or rest it on the rim. If you are using bitters, dot them on the foam and drag a toothpick through for a design.
!Rubbing the peel on the rim instead of spraying the oils wastes the aroma.

Serve

Serve it right away in the chilled coupe while the foam is thick and the drink is cold. Do not add ice to the glass.

Variations

Ingredient substitutions

Each row shows what you can swap in place of an original ingredient, and how the drink changes.

Swap options for Bourbon Whiskey

Bourbon WhiskeyRye Whiskey
Match
Common availability
Bourbon Whiskey → Rye Whiskey: Makes the drink spicier and drier, with less caramel sweetness.

Swap options for Egg White

Egg WhiteAquafaba
Match
Common availability
Egg White → Aquafaba: Provides similar foam without the egg, though slightly less rich.

Swap options for Simple Syrup

Simple SyrupMaple Syrup
Match
Common availability
Simple Syrup → Maple Syrup: Adds an earthy, richer sweetness that pairs well with bourbon.

Similar cocktails

Cousin drinks that share DNA with this one — each profile stands on its own.

Similar cocktail

Whiskey Sour

The Whiskey Sour lacks the egg white, making it sharper and lighter in texture.

Match

They taste almost identical in flavor, but the Boston Sour feels much softer and silkier in the mouth compared to the sharper, thinner Whiskey Sour.

In common: base spirit, citrus, sweetener

Ingredients

Both share

Bourbon Whiskey, Fresh Lemon Juice, Simple Syrup

Only in Boston Sour

Egg White

The Boston Sour adds an egg white to the classic Whiskey Sour template, creating a richer texture and a foamy top.

Flavor

Shared flavors

whiskey-citrus backbone, sweet-sour balance

How Whiskey Sour differs

creamier, thicker mouthfeel, foamy cap

View recipe & details →

Similar cocktail

Clover Club

The Clover Club uses gin and raspberry instead of bourbon.

Match

Both have that signature frothy top and tart bite, but the Clover Club is lighter and fruitier while the Boston Sour is warmer and spirit-driven.

In common: citrus, sweetener, egg white foam

Ingredients

Both share

Fresh Lemon Juice, Simple Syrup, Egg White

Only in Boston Sour

Bourbon Whiskey

Only in Clover Club

Gin, Raspberry Syrup

Swapping bourbon for gin and adding raspberry syrup changes the base spirit and adds a fruity note.

Flavor

Shared flavors

silky egg white texture, tart citrus profile

How Clover Club differs

gin botanicals, fruity sweetness, lighter body

View recipe & details →

History

Origin

The Boston Sour is essentially a Whiskey Sour with the addition of an egg white, a variation that gained its own name in the late 19th century. The egg white was originally added to soften the harshness of the available spirits, creating the signature foamy cap.

Era: 1880s
Confidence

The Boston Sour is widely accepted as a Whiskey Sour with egg white, though some older recipes occasionally float red wine on top instead.

Practical

Tips & pitfalls

What works at home and what to skip when making this drink.

Tips

Worth knowing before you pour

Dry shake first to get a thick foam before adding ice.
Use a large ice cube for the wet shake to chill fast without over-diluting.
Make sure your egg is fresh and keep it refrigerated until use.

Avoid

Common mistakes

Skipping the dry shake leaves you with thin, watery foam.
Using bottled lemon juice makes the drink taste flat and metallic.