noun (plural) From sulphur + -ite (a salt or ester of sulphurous acid); sulphur from Latin sulphur

Sulphites /ˈsʌlfaɪts/

Sulphur-containing compounds — primarily sulphur dioxide (SO₂) — used in winemaking as an antioxidant and antimicrobial preservative. Present in almost all wine naturally; routinely added by most producers. Required by law to declare on labels in the EU and UK above 10 mg/L.

How SO₂ is used in winemaking

Antioxidant

SO₂ binds to oxygen in the wine and prevents oxidation — the browning and flat, sherry-like deterioration that affects wine exposed to air.

Antimicrobial

Kills or inhibits unwanted bacteria and wild yeasts. Applied at crush to suppress spoilage organisms before fermentation begins with a chosen yeast strain.

Fermentation control

Added post-fermentation to stop or slow secondary fermentation (e.g. malolactic fermentation) in wines where this is not desired — many whites and rosés.

Bottle stability

Added at bottling to protect the wine during transport and storage, preventing re-fermentation and oxidation once sealed.

Natural vs added sulphites

Sulphur dioxide is produced naturally by yeast during fermentation — most wines contain 10–40 mg/L of SO₂ without any additions. Winemakers add further SO₂ at harvest, after fermentation, and at bottling to control oxidation and microbial activity. The total amount in the finished wine depends on style, intended shelf life, and the winemaker's philosophy. Natural wine producers typically add little or no SO₂ and rely on careful hygiene, sterile filtration, or other techniques to stabilise the wine. Without SO₂ protection, wines are more vulnerable to oxidation and spoilage, which is why most are best drunk young.

The label declaration

EU and UK law requires all wines above 10 mg/L total SO₂ to declare "contains sulphites" (or "contains sulfites" in the US). Since almost every wine exceeds this threshold — including most natural wines — the declaration is near-universal and conveys little information about actual levels. There is no legal requirement to state the exact SO₂ level on the consumer label, though technical datasheets for trade buyers typically include this.

Sources: EFSA (EU Food Safety Authority — sulphite safety assessments); OIV (maximum SO₂ limits by wine style); WSET (oenology curricula on SO₂ use). Last updated: 2026-10-19. Corrections via the contact form.

Questions

About sulphites.

Are sulphites in wine harmful?

For the vast majority of people, no. Sulphites at wine's typical levels (20–200 mg/L total SO₂) are well-established as safe by the WHO, EU food safety authority (EFSA), and Australian, US and UK regulators. Genuine sulphite allergy (IgE-mediated) is rare — affecting roughly 0.05% of the population — and is more commonly associated with dried fruit, preserved meats and other foods that contain far higher levels of SO₂ than wine. The popular belief that sulphites cause wine headaches is not supported by the clinical evidence; headache research more commonly points to histamines, tyramine, alcohol itself, or tannins as contributors. See the natural wine and sulphite debate for a fuller treatment of the claims and evidence.

How much SO₂ is typically in wine?

Wines contain both free SO₂ (active, protective fraction) and bound SO₂ (combined with compounds in the wine and inactive). Total SO₂ levels vary considerably by style. Sweet wines require more SO₂ to prevent re-fermentation (up to 200–250 mg/L total). Dry red wines typically contain 50–100 mg/L total. Dry whites and rosés 70–130 mg/L. Natural and low-intervention wines often aim for under 30 mg/L total, sometimes none. EU maximum legal limits are 150 mg/L total for dry reds, 200 mg/L for dry whites, and 400 mg/L for certain sweet wines. By comparison, a 100g serving of dried apricots contains around 1,000–3,000 mg/kg SO₂.

What does "contains sulphites" on the label mean?

"Contains sulphites" (or "contains sulfites" in American English) is a legally required allergen declaration in the EU, UK, US and Australia for wines above 10 mg/L total SO₂. This is a threshold so low that virtually all wine — including "natural" wines — exceeds it due to SO₂ produced naturally by yeast during fermentation (typically 10–40 mg/L). A wine labelled "no added sulphites" (NAS) or "sans soufre ajouté" may still display "contains sulphites" on the label because the naturally produced amount exceeded the threshold. The label tells you sulphites are present; it does not indicate how much. See natural wine explained for how natural producers approach SO₂.

Can wine be made without any sulphites?

Wines with zero total SO₂ are extremely rare because yeast produces SO₂ as a metabolic byproduct during fermentation — most wines will have at least 10–30 mg/L naturally. Some producers using very carefully selected yeasts in very controlled conditions can achieve very low levels, but "truly zero" sulphite wine is uncommon. "No added sulphites" (NAS) wines contain no deliberately added SO₂ — these are more widespread in the natural wine movement and require very clean fruit, careful cellar hygiene, and typically earlier drinking, since SO₂ is the main tool for preservation. Without it, wines are more vulnerable to oxidation and microbial faults. See common wine faults.

Why do white wines generally have more SO₂ than red wines?

Tannins in red wine provide some natural antioxidant protection, partially substituting for SO₂. Whites and rosés lack this tannin buffer, so they need more SO₂ to achieve equivalent oxidation protection. Additionally, many white wines are deliberately made without malolactic fermentation (to preserve freshness and acidity), and SO₂ is the standard tool for suppressing malolactic bacteria. Sweet wines have the highest SO₂ levels of all because residual sugar creates a risk of re-fermentation in bottle — higher SO₂ suppresses any remaining yeast and keeps the wine stable.