Sulphite allergy and sensitivity: the 10 mg/kg rule, and where sulphites appear on a menu
By the Menulta editorial team · Facts checked 15 October 2026 · Updated 15 October 2026
The short answer
Sulphites are preservatives, such as sulphur dioxide (E220) and sodium metabisulphite (E223), used in wine, dried fruit, some vinegars, processed potatoes, and some prawns and cured meats. Some people, especially those with asthma, are sensitive to them and can react with wheezing or other symptoms. In EU law, sulphur dioxide and sulphites must be declared when present above 10 mg/kg or 10 mg/litre, expressed as total SO2, in the food as ready to eat.
What sulphites are
Sulphites are sulphur-based compounds that prevent browning and stop the growth of bacteria and yeasts. They are authorised food additives in the E220 to E228 range, including sulphur dioxide (E220), sodium sulphite (E221), sodium metabisulphite (E223) and potassium metabisulphite (E224). They also occur naturally in small amounts during fermentation, which is why all wine contains some sulphites.
Sulphite sensitivity
Reactions to sulphites are usually described as sensitivity or intolerance rather than classic allergy, because many do not involve IgE antibodies. They are most common in people with asthma, where sulphites can trigger wheezing, chest tightness or coughing, sometimes severely. Others report flushing, hives or digestive symptoms. Because reactions can be serious for asthmatic guests, sulphites are treated as a declarable allergen in EU law.
The 10 mg/kg rule
Annex II lists 'sulphur dioxide and sulphites at concentrations of more than 10 mg/kg or 10 mg/litre in terms of the total SO2, which are to be calculated for products as proposed ready for consumption or as reconstituted according to the instructions of the manufacturers'.
Two parts matter. The threshold applies to the finished food as served, not to a single ingredient. And it is measured as total SO2. A dish containing wine, dried fruit and a sulphited ingredient can exceed the threshold even if each component seems minor. When in doubt, and especially with wine-based sauces, declare it.
Where sulphites appear on a menu
| Source | Notes |
|---|---|
| Wine | Labels must say 'contains sulphites' when above 10 mg/l; almost all wines do |
| Wine-based sauces and reductions | Sulphites carry through, depending on quantity |
| Beer and cider | Some contain added sulphites |
| Dried fruit | Dried apricots, raisins and sultanas are often sulphited |
| Vinegars | Wine vinegar and some balsamic vinegars |
| Prawns and crustaceans | Sometimes treated with metabisulphite to prevent black spot |
| Processed potatoes | Some frozen chips, peeled potatoes and potato products |
| Sausages and burgers | Sulphites are permitted in some fresh sausages and burger meat in the UK and EU |
| Soft drinks and cordials | Some fruit-based drinks |
| Pickles and condiments | Some pickled vegetables and sauces |
Declaring sulphites in practice
Start with wine and drinks, which are the most obvious source, and make sure the drinks list is part of the allergen record. Then check recipes that use wine, dried fruit, vinegar or bought-in processed ingredients. Supplier specifications often state sulphite content, so ask for them for dried fruit, prawns, sausages and processed potatoes.
Many kitchens choose to declare sulphites on any dish containing wine, wine vinegar or dried fruit, rather than calculating total SO2 for each recipe. That is a cautious approach that protects asthmatic guests.
Sulphites at the bar
The bar is the biggest source of sulphites in most restaurants. Almost all wines contain them, and many beers, ciders, cordials and some pre-mixed cocktail ingredients do too. Bar staff should know which drinks contain sulphites and be able to tell an asthmatic guest. Including the drinks list in the allergen record, rather than leaving it to bottle labels, makes that possible during service.
Questions to ask suppliers about sulphites
Ask suppliers for sulphite information on dried fruit, prawns and other crustaceans, sausages and burger meat, frozen and processed potato products, pickles, vinegars and fruit-based drinks. Ask whether the sulphite content is above 10 mg/kg as supplied, and remember that dilution or concentration during cooking changes the amount in the finished dish. Record the answers and repeat them when a product changes.
When a guest says they react to sulphites, the safest response is to avoid all dishes containing wine, wine vinegar, dried fruit or sulphited ingredients, and to suggest drinks without added sulphites, rather than trying to calculate whether a dish is just under the threshold.
Sources
This guide is general information, not medical or legal advice. Guests with an allergy should follow their doctor's advice. Operators should confirm their own setup with their food safety adviser or local authority.