The Truth About Sulphur In Wine

Wine Hobbyist
Jul 27
3 min read

You’ve probably seen the words “contains sulphites” on a wine label and wondered, "Should I be worried?", given the chatter on the topic. It could be a friend saying, "I cannot drink wine because of the sulphites - they give me headaches," or winemakers stating that their wine contains "no added sulphites" in a tone that positions it as a feature.

Sulphites, like tannins, are a highly misunderstood element in wine, so let’s chat sulphur in wine, particularly, why it’s there, what it means for you, and just how much is really in your glass.

Wooden barrel lid on beige wall, with "SO₂" written in blue. The wood texture is prominent, conveying a rustic vibe.

What Is Sulphur Dioxide, and Why Is It in Wine?

Sulphur dioxide (SO₂) is a compound naturally produced in small amounts during fermentation, but winemakers may add it intentionally. Why? SO₂ does much to preserve a wine:

It protects against spoilage
Keeps the wine fresh
Prevents it from turning into an accidental vinegar science experiment

In short, SO₂ helps your wine taste as the winemaker intended, and for longer, improving a wine's ageability. Sulphur is also used in vineyards to fight off powdery mildew, a threat that could otherwise wipe out an entire crop.

How Much Sulphur Is Actually in Wine?

Before we get into the regulations and the allowable amount of sulphur in wine, it is essential to establish that, in practice, many commercial winemakers aim to keep SO₂ in the range of roughly 25-30 mg/L, adjusting dosages based on pH levels (a measurement of acidity) and wine style. For context, dried fruit can contain up to 1,000mg/L!

Very nearly all wines have some sulphur dioxide, or its sulphite compounds, added during winemaking or before bottling because this is the most effective means of protecting wine from oxidation and microbial instability.

~Caroline Gilby, Master of Wine and scientist, The Wine Society, UK

How Much Sulphur Is Allowable In Wine By Law?

Most wines contain between 10 and 200 milligrams per litre (mg/L) of total sulphur dioxide.

For dry European red wines, government regulations set the maximum at around 150–160 mg/L, while whites and rosés can reach up to 200–210 mg/L. If there’s a bit of sweetness left in the wine, those limits can climb a bit higher, sometimes up to 400mg/L in special dessert wines.

In Canada, table wines (like most reds, whites, and rosés) are allowed up to 300mg/L of total sulphur dioxide, and up to 400mg/L for sweeter styles.

Lastly, when it comes to labelling, regardless of the wine's origin, sulphites above 10mg/L require the label to state "contains sulphites."

Does Sulphur Affect Taste?

Here’s where passion and debate collide! Most drinkers won’t detect sulphur at all. The threshold at which SO₂ becomes perceptible is typically between 30 and 50mg/L, well above what most wines aim for. In higher amounts, sulphur can make a wine taste a bit tight, dry, or even give off faint aromas reminiscent of a just-struck match. Some natural wine advocates feel it can “mute” a wine’s personality, while others see it as an essential tool for consistency and age-worthiness.

Wines labelled “no added sulphites” exist, but even these have at least trace amounts, thanks to natural fermentation. The tradeoff for going completely sulphur-free can be funkier flavours (some of which I am a fan of), more variation from bottle to bottle, and a shorter, less stable shelf life.