Why Every Wine Label Says “Contains Sulfites”: The 1986 Salad-Bar Ban and What Sulfites Really Do

In the early 1980s, the salad bar was the healthiest thing in an American restaurant, and for a small number of diners it was the most dangerous. Lettuce, cut potatoes and sliced fruit were being dipped in sulfite solutions to keep them crisp and white for hours, and FDA began receiving reports of asthma attacks, some severe, from people who had just eaten them. By July 1986 FDA had banned sulfites on fresh fruit and vegetables, and within a year every new bottle of American wine with 10 ppm or more of sulfur dioxide had to carry two words on its label: Contains sulfites.

That warning is now so familiar that most people read it as a statement about wine. It is really a statement about lettuce, and about a 1985 scientific review that found most people tolerate sulfites but that they can pose a hazard “of unpredictable severity” to a sensitive minority. This guide explains what sulfites are, why winemakers still use them, why “sulfite-free” wine is harder to make than it sounds, and what the evidence now says about the famous wine headache.

This is a chemistry and regulatory explainer. It is not medical advice. If you think you react to sulfites, the right person to talk to is an allergist, not a chemical distributor.

Last reviewed 6 October 2026 against the current text of 21 CFR and 27 CFR, TTB and USDA guidance, Health Canada and the peer-reviewed literature cited below. How we researched it is set out at the end.

What are sulfites?

Sulfites are compounds that release sulfur dioxide (SO₂) or the bisulfite ion (HSO₃⁻) when they dissolve in water, and in food and wine that SO₂ does two jobs: it slows oxidation and it inhibits spoilage microbes. The word covers a family of six sulfiting agents that US food law groups together: sulfur dioxide gas itself, sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite and potassium metabisulfite.

All six listings carry the same three exclusions: not in meats, not in foods recognised as a source of vitamin B1, and not on fruit or vegetables served or sold raw or presented as fresh.

The one you are most likely to meet as a white powder is sodium metabisulfite, Na₂S₂O₅, CAS 7681-57-4. It is two bisulfite units that have lost a molecule of water. Drop it in water and it reverses that step:

Sulfites are not exotic. Yeast make small amounts of SO₂ on their own during fermentation, which is why no wine is truly sulfite-free. Industrially, the same chemistry that protects a white wine also strips chlorine from water before it reaches a membrane or a river; our engineering guides cover sodium bisulfite for dechlorination and boiler oxygen scavenging. This article stays with food and wine.

Why does every wine label say “Contains sulfites”?

Every US wine label says “Contains sulfites” because federal rules have required it since 1987 for any wine with 10 ppm or more total sulfur dioxide, and nearly every wine crosses that line. The rule was the second half of a response that began in restaurants, not wineries.

1982–1985: the reports come in

In 1982 FDA proposed to reaffirm that sulfiting agents were “generally recognized as safe.” Instead of a quiet confirmation, the agency started receiving reports of adverse reactions, the most serious among people with asthma, many of them after eating at salad bars where produce had been sprayed or dipped to stop it browning. FDA asked the Federation of American Societies for Experimental Biology (FASEB) to review the evidence. Its 1985 report concluded that most people tolerate sulfites but that they could pose a hazard of unpredictable severity to asthmatics and others who are sensitive to them. The University of Nebraska–Lincoln Food Allergy Research and Resource Program notes that FDA was aware of deaths among sulfite-sensitive asthmatics.

July 1986: the salad-bar ban

On 9 July 1986 FDA published the rule (51 FR 25025) that prohibited sulfites on fruit and vegetables intended to be served raw or presented fresh to the public. The restriction is still in the federal listing for sodium metabisulfite today, word for word: it is generally recognized as safe “except that it is not used in meats; in food recognized as a source of vitamin B1; on fruits or vegetables intended to be served raw to consumers or sold raw to consumers, or to be presented to consumers as fresh.”

Each of the three exclusions has a reason. Raw produce was where the reactions were happening. Meat is excluded because sulfites can restore a fresh red colour to meat that is no longer fresh. And foods recognised as a source of vitamin B1 are excluded because sulfite cleaves thiamine (vitamin B1) at the bridge between its two rings, destroying the vitamin in the food it was supposed to protect.

1987: the words go on the bottle

Packaged foods got a labelling rule: a sulfiting agent is only considered “insignificant” if none is detectable, and FDA defines detectable as 10 ppm or more in the finished food. Wine and beer fall under the Alcohol and Tobacco Tax and Trade Bureau (TTB), which wrote the matching rule into 27 CFR 4.32(e). A wine must state “Contains sulfites” (or name the sulfiting agent) whenever sulfur dioxide is detected at 10 ppm or more, measured as total SO₂. The rule applied to label approvals issued from 9 January 1987, to all wine bottled from 9 July 1987, and to all wine removed from bond from 9 January 1988.

Notice what the label does not say. It does not say how much. A wine at 12 ppm and a wine at 300 ppm carry the same two words. The declaration is a trigger for a sensitive minority, not a dose indicator for everyone else.

Why do winemakers add sulfites?

Winemakers add sulfites because SO₂ protects wine against oxidation and inhibits spoilage yeast and bacteria, and for most styles there is still no single substitute that does both. It is usually added at the crusher, again after fermentation, and again before bottling, as potassium or sodium metabisulfite, Campden tablets, liquid SO₂ or, in an old practice still used to keep empty barrels sound, burning sulfur.

The chemistry that matters to a winemaker is not the total SO₂ on the label but how much of it is free, and how much of the free SO₂ is molecular. Some SO₂ binds to acetaldehyde and sugars and does nothing more. Of the free fraction, most sits as the bisulfite ion at wine pH; only the small molecular SO₂ fraction does most of the work against microbes. That fraction depends steeply on pH, because molecular SO₂ and bisulfite are linked by an acid–base equilibrium with a pKa of about 1.81.

Total SO₂

Everything: free plus bound. This is the number the “Contains sulfites” rule (10 ppm) and the 350 ppm legal ceiling are measured against.

Bound SO₂

SO₂ that has combined with acetaldehyde, sugars and other compounds in the wine. It no longer protects anything.

Free SO₂

The unbound fraction, present as molecular SO₂, bisulfite and a trace of sulfite. Winemakers measure and manage this number.

Molecular SO₂

The small, pH-dependent share of free SO₂ that does most of the work against spoilage microbes.

Calculated from molecular fraction = 1 / (1 + 10^{pH − 1.81}). The 0.8 mg/L molecular target is the figure widely used in extension guidance for dry table wine; the results match the pH 3.0 and 3.5 values published by university extension programmes.

Read the table from the bottom up and the logic of modern winemaking appears. A soft, ripe, high-pH red needs four to six times more free SO₂ to get the same protection as a crisp, low-pH white. That is also why a winemaker who wants to use less SO₂ starts by managing pH, hygiene and oxygen, not by simply adding less powder.

What are Campden tablets?

Campden tablets are pressed tablets of potassium or sodium metabisulfite, sold to home winemakers and brewers as a pre-measured SO₂ dose; the common retail size is about 0.44 g. Because the two salts deliver different amounts of SO₂, the same tablet does not give the same dose:

Theoretical maximum from molar masses; the free SO₂ you measure afterwards will be lower because part binds immediately. Tablet mass varies by brand, so check the packet.

If you make wine at home and need an addition rate per gallon or per litre, our sodium metabisulfite guide covers the arithmetic and the grade choices. Clean equipment matters as much as the addition itself; see the winemaker’s guide to cleaning with soda ash.

Is there such a thing as sulfite-free wine?

No wine is entirely sulfite-free, because yeast produce sulfur dioxide during fermentation; what exists is wine with no added sulfites, and some of those still test above 10 ppm and must carry the label. TTB requires the declaration on the measured result, not on whether the winery added anything, and it accepts sulfite waivers only on test results from its own Beverage Alcohol Laboratory. Even then, TTB warns that naturally occurring sulfite levels vary from batch to batch and vintage to vintage, and the bottler stays responsible for labelling every batch correctly.

The organic wine rules add a second layer, and they are where most of the confusion comes from:

So a bottle that says “made with organic grapes” and “contains sulfites” is not contradicting itself. The grapes are organic; the winemaking used up to 100 ppm SO₂, which the USDA “organic” category does not allow. Rules in other countries differ; European organic wine, for example, allows added sulfites at reduced limits, which is why some imported organic wines carry the sulfite warning when sold in the US.

Do sulfites cause wine headaches?

Probably not, for most people. The sulfite story has never fit the evidence well, and the strongest current hypothesis points somewhere else. Three observations have always made sulfites an awkward suspect:

• White wines usually carry more SO₂ than reds. Red wine’s tannins and pigments give it some protection against oxidation, so reds are often made with less added SO₂. Yet the “red wine headache” is the one people describe.
• Dried fruit carries far more. Light-coloured dried fruit such as apricots is sulfited to keep its colour, and the EU permits up to 2,000 mg/kg (about 2,000 ppm) of SO₂ in it, more than five times the 350 ppm US ceiling for wine.
• Sulfite sensitivity looks different. The reactions that drove the 1986 ban were mostly respiratory, concentrated among people with asthma.

In November 2023, researchers at the University of California, Davis published a study in Scientific Reports proposing a different mechanism. Apramita Devi, Morris Levin and Andrew Waterhouse found that quercetin glucuronide, a metabolite of the flavonol quercetin that is abundant in red wine, inhibits ALDH2, the enzyme that clears acetaldehyde, a toxic breakdown product of alcohol. The paper’s own title calls it what it is: a new hypothesis. It is a laboratory result that still needs human trials, but it explains the red-not-white pattern that the sulfite theory never could.

Are sulfites bad for you?

For most people sulfites at food and wine levels cause no reaction, and FDA lists sodium metabisulfite as generally recognized as safe under good manufacturing practice, with the three exclusions above; for a sensitive minority they can trigger serious reactions, which is the whole reason for the label. FDA estimates that about one person in a hundred is sulfite-sensitive. University of Florida IFAS food-science guidance puts sensitivity at about 5% of people with asthma, against about 1% of people without it.

Two practical facts follow from the regulations themselves:

• The label threshold is 10 ppm, not zero. A food or wine below 10 ppm does not have to declare sulfites, and a wine below 10 ppm may say “contains less than 10 ppm sulfites.”
• Fresh produce should not be sulfited at all. Since 1986, sulfites on raw fruit and vegetables served or sold as fresh have been prohibited in the US. Sulfites do still appear legitimately in dried fruit, some juices, wine, some processed potato products and other packaged foods, and they must be declared at 10 ppm or more.

Anyone who has had a reaction should get a diagnosis from a qualified clinician. Nothing in this article is a substitute for that.

Is a sulfite allergy the same as sulfite sensitivity?

No. Health Canada states that sulphites “do not cause true allergic reactions” but can produce allergy-like symptoms in sensitive people, which is why clinicians usually speak of sulfite sensitivity or intolerance rather than allergy. The difference matters in practice: Health Canada also notes that “there is no allergy testing available for sulphites,” so a negative skin-prick or blood test does not rule a reaction out.

According to Health Canada, the most common symptoms are wheezing, chest tightness and coughing; others include flushing, a fast heartbeat, hives, dizziness, stomach upset and diarrhoea. People with asthma are most at risk, and Health Canada estimates sensitivity affects about 5–10% of them, a slightly higher range than the 5% figure in older US extension guidance. Anaphylaxis from eating sulfites has been described but is, in Health Canada’s words, “very rare.”

That is why the label threshold sits at 10 ppm rather than at a level chosen for flavour or shelf life: it exists so that the sensitive minority can read the label and decide for themselves.

Where else are sulfites in food?

Beyond wine, sulfites turn up wherever a food needs to keep its colour or resist spoilage without refrigeration: dried fruit (especially apricots, golden raisins and other light-coloured fruit), bottled lemon and lime juice, some grape juices, dried and dehydrated potato products, some pickled foods, molasses and some shellfish, where they prevent black spots on shrimp. In packaged food, the ingredients list will name the agent (“sodium metabisulfite,” “sulfur dioxide”) or the label will carry a sulfite declaration once the finished food reaches 10 ppm.

The reasoning behind each use is the same chemistry in a different setting. In dried fruit, SO₂ blocks the browning reactions that turn a cut apricot brown. In juice and wine, it mops up oxygen-derived compounds and holds back microbes. In shrimp, it interrupts the enzyme that causes black spot. The 1986 rule did not end these uses; it ended the one where a customer could not see or read a label: the open salad bar.

For a broader view of how preservatives move through US regulation, see our coverage of FDA’s reassessment of the preservative BHA.

Sodium or potassium metabisulfite: which is used in wine?

Both are used in wine; potassium metabisulfite is the more common choice in home winemaking because it adds potassium rather than sodium, while sodium metabisulfite delivers more SO₂ per gram and is widely used in food processing and in commercial production. Campden tablets are sold in both sodium and potassium forms. The SO₂ they release is the same molecule either way.

Alliance Chemical lists sodium metabisulfite, not potassium metabisulfite. If you are buying sodium metabisulfite for food or beverage work, use the Sodium Metabisulfite – Food-Grade listing rather than the Technical Grade, which is sold for industrial uses such as dechlorination. For laboratory work there is an ACS Reagent Grade. Tell us the application and we will help you match the grade, and ask for a certificate of analysis on the lot you are buying. This article makes no claim about ours beyond what each product listing states.

Key numbers and sources