Sweet vermouth is aromatised, fortified wine — red-brown, bittersweet, and the ingredient that makes a Manhattan a Manhattan. The single most important thing about it is the thing most people get wrong: it is wine, so it goes off. A bottle open on a warm shelf for six months is why your Negroni tastes dusty.

What is sweet vermouth?

Vermouth is wine, fortified with spirit and flavoured with botanicals, of which one is compulsory. Under EU rules:

• At least 75% wine by volume
• Flavoured with species of Artemisia — wormwood — which is non-negotiable and is where the name comes from, via the German Wermut
• Fortified to between 14.5% and 22% ABV; most sit at 15–18%
• Sweetened — "sweet" on an EU label means at least 130 grams of sugar per litre

Sweet vermouth is also called rosso or Italian vermouth, reflecting where the style was commercialised. Its colour comes from caramel, not from red wine — most sweet vermouth is made from a white wine base.

Vermouth di Torino is a protected designation requiring production in Piedmont and the use of Italian wine, which is a genuine quality signal.

How it's made

Start with a fairly neutral base wine, usually white. Infuse or macerate botanicals — wormwood first, then some combination of gentian, cinchona, cardamom, cinnamon, clove, vanilla, bitter orange peel, saffron, rhubarb and marjoram; recipes run to several dozen ingredients and are generally secret. Blend the extracts in, fortify with grape spirit to arrest fermentation and stabilise the wine, sweeten with sugar or caramel, chill, filter and bottle.

The fortification is what lets vermouth survive at all — unfortified aromatised wine would spoil in days. But fortifying to 17% is not fortifying to 40%, and that is the crux: vermouth is far more perishable than any spirit on your shelf.

What it tastes like

Sweet but bitter underneath — that is the shape. Dried cherry, fig, orange peel, cocoa, vanilla, clove, and a persistent bitter-root finish from the wormwood and gentian. Good sweet vermouth tastes like something you would drink on its own over ice, which is the easiest test of whether yours is still alive.

Oxidised vermouth tastes flat, dusty, sherry-like and vaguely of stewed fruit, with the bitterness gone and a sourness in its place. It will not make you ill; it will make every drink you put it in taste tired.

Styles worth knowing

Style	Character	In a drink
Classic rosso	Balanced, cocoa and orange	The default Manhattan and Negroni vermouth
Vermouth di Torino	Protected Piedmont production	Richer and more bitter; excellent in both
Vermouth Chinato / Carpano Antica style	Heavy vanilla, intense, higher sugar	Assertive — it will lead the drink, so pour slightly less
Bianco	Sweet but pale and floral, lower bitterness	A different drink; not a rosso substitute
Rosé / rosato	Between rosso and bianco	Good in spritzes and lighter stirred drinks
Low-alcohol / NA aperitif wines	Dealcoholised, often sweeter	Usable; expect to add bitterness back

Which bottle to buy

Buy the smallest bottle you can find. This is the most useful advice on the page. A 375ml bottle you finish in three weeks beats a litre that goes stale at the two-month mark, even though the litre looked like better value.

Beyond that: buy a well-regarded Vermouth di Torino or a classic Italian rosso for Manhattans and Negronis. Keep in mind that the big, vanilla-heavy styles are delicious but dominant — if you use one in a Manhattan, consider dropping from an ounce to three-quarters.

And check the bottling or best-before date on the shelf. Vermouth sitting unsold under supermarket lighting for two years is already compromised before you open it.

Using it in drinks

Sweet vermouth is a modifier that behaves like a base — it is often a third or more of the glass, so its condition matters enormously. The Manhattan is rye and sweet vermouth with bitters; the Negroni is equal parts gin, Campari and sweet vermouth; the Americano is Campari, sweet vermouth and soda, where it is fully half the drink.

It is also excellent simply poured over ice with a twist and a splash of soda, which is how it is drunk across Italy and Spain and how you should assess a new bottle.

Two practical notes. Vermouth brings sugar, so a recipe using it rarely needs added syrup. And because it is only 15–18% ABV, swapping it for a spirit in the same slot changes the strength of the drink substantially.

Substitutes

Another sweet vermouth is the obvious answer, allowing for the vanilla-heavy styles being more assertive. Amaro — Averna in particular — substitutes well in stirred drinks and makes a darker, more bitter result; drop the sugar elsewhere. Cream sherry or an oloroso covers the dried-fruit register at a similar strength, without the wormwood bitterness. Port works in a pinch but is sweeter and lacks the bitter finish. Bianco vermouth is not a substitute — it is a different flavour and a much paler drink.

Storage

This is the section that matters. Refrigerate sweet vermouth the moment you open it, and treat it as a wine.

• Open, refrigerated: good for about a month, declining after that
• Open, at room temperature: noticeably tired within a week or two
• Unopened: a year or two, stored upright and away from light and heat

Decanting into a smaller bottle as the level drops genuinely helps, because the enemy is the volume of air in the bottle. A vacuum stopper helps too. If you only make a Manhattan occasionally, buy small and accept the higher unit price — it is cheaper than throwing away two-thirds of a litre.

Questions

Does sweet vermouth go bad? Yes. It is fortified wine at roughly 17% ABV, not a spirit, and it oxidises. Refrigerated it is good for about a month; left on a shelf it is past its best in a week or two.

Why does my Manhattan taste dull? Almost always the vermouth. Pour a little neat — if it tastes flat, dusty or sour rather than bittersweet and aromatic, that is your answer.

Is sweet vermouth made from red wine? Usually not. Most is made from a neutral white base and coloured with caramel.

What is the difference between sweet and bianco vermouth? Both are sweet, but rosso is caramel-coloured, bitter and spiced, while bianco is pale, floral and softer. They are not interchangeable.

Does vermouth really contain wormwood? Yes — it is legally required. The thujone content is regulated and far below the levels in historical absinthe folklore.