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Allergen Deep Dive: Sulphur Dioxide

Despite the fact that allergies are more prevalent than ever, and allergens have never been a hotter topic in the food industry, most people know very little about sulphur dioxide.

Last month we did an allergen deep dive into milk and the different reactions it can trigger, and as we celebrate National Prosecco Day it’s the perfect time to turn our attention to sulphur dioxide (and sulphites) - one of the 14 major food allergens.

Used as preservatives sulphur dioxide (E220) and other sulphites (from numbers E221 to E228) - to give them their technical names - can be found in a much larger variety of food and drink than you’d expect. Allergies and sensitivities to sulphur dioxide are more common in people with asthma, though it’s possible to have just one.

Read on to find everything you need to know about a sulphur dioxide allergy, including what food and drinks to avoid and what to look out for on a label...

What is sulphur dioxide?

Sulphites are preservatives added to food and drinks to extend shelf life. Sulphites work as food preservatives by releasing the sulphur dioxide, a gas. The term ‘sulphites’ covers a group of chemicals (and can also include sulphur dioxide).

Can you be allergic to sulphur dioxide?

Yes, you can be allergic to sulphur dioxide, and/or sulphites. However, more people have an intolerance or sensitivity to sulphur dioxide than an allergy, particularly if they suffer from asthma - sulphur dioxide can irritate the lungs and throat.

What is a sulphur dioxide allergy?

An allergy to sulphur dioxide (and/or sulphites) will trigger a negative reaction from a person’s immune system if they consume a food or drink containing sulphur dioxide.

An allergy occurs when a person’s body misidentifies a harmless substance as being dangerous, and triggers a reaction from the immune system. These reactions can vary, and include anything from uncomfortable itching to life-threatening anaphylaxis.

An allergy is different to an intolerance, with the former affecting the immune system and an intolerance not affecting the immune system. A sensitivity to a substance means that its effects (such as caffeine being a stimulant) are felt more keenly than usual.

What is a sulphur dioxide intolerance?

An intolerance to a food or drink is different to an allergy because it does not affect the immune system. It prompts a negative reaction from other areas of the body - very often the digestive system.

With sulphur dioxide intolerance specifically, the sulphur dioxide can irritate the throat - causing it to constrict. This may also cause coughing, wheezing and a tight chest.

Sulphur dioxide (and sulphites) also commonly provoke and aggravate eczema.

It’s important to understand that allergies and intolerances can share symptoms, but only an allergy can trigger anaphylaxis, so getting the correct diagnosis and medication is critical.

What food and drinks do you find sulphur dioxide?

Most people associate sulphur dioxide with wine and beer, which naturally contain sulphites and also have them added during the manufacturing process to kill bacteria and improve preservation.

However the highest levels of sulphites are actually found in dried fruits (and vegetables) - particularly those with a light colour.

Sulphur dioxide (and/or sulphites) can be found in these food and drinks:

  • Wine
  • Beer
  • Cider
  • Soft drinks
  • Fruit juices
  • Condiments
  • Sausages and burger meat
  • Jam
  • Pickled foods and vinegar
  • Dried fruit eg dried apricots, prunes, raisins
  • Maraschino cherries
  • Tinned coconut milk
  • Vegetable juices
  • Grape juice
  • Bottled lemon juice and lime juice
  • Pickles
  • Vinegar
  • Fresh or frozen prawns
  • Some processed meat products

What are surprising foods that contain sulphur dioxide

You might find sulphur dioxide/sulphites in the following unexpected foods:

  • Cereal
  • Ketchup
  • Mustard
  • Guacamole
  • Dehydrated, pre-cut or peeled potatoes
  • Relish
  • Pre-packaged flavoured noodles
  • Pre-packaged flavoured rice
  • Horseradish
  • Relish
  • Molasses
  • Dehydrated fish

What are other names for sulphur dioxide?

Sulphur dioxide and sulphites can sometimes be labelled under other names. These are:

  • Sulphur
  • Sulphur Dioxide
  • Sulphite
  • Sulphites
  • Potassium bisulphite
  • Metabisulphite
  • Sodium bisulphite
  • Dithionite
  • Metabisulphite
  • Sulphiting agents
  • Sulphurous acid
  • E220 Sulphur dioxide
  • E221 Sodium sulphite
  • E222 Sodium hydrogen sulphite
  • E223 Sodium metabisulphite
  • E224 Potassium metabisulphite
  • E226 Calcium sulphite
  • E227 Calcium hydrogen sulphite
  • E228 Potassium hydrogen sulphite
  • E150b Caustic sulphite caramel
  • E150d Sulphite ammonia caramel

What does an allergic reaction to sulphur dioxide look like?

Though the symptoms of an allergic reaction to sulphur dioxide/sulphites might be different for different people, there are some common indicators, including:

  • Red, itchy rash (either raised or not raised)
  • Dizziness
  • Vomiting and nausea
  • Mouth itching or tingling
  • Shortness of breath and/or wheezing
  • Sneezing
  • Diarrhoea
  • Face, mouth and/or throat swelling
  • Abdominal pain
  • Difficulty swallowing

An allergic reaction may also result in anaphylaxis. This can be fatal, and the symptoms include:

  • Difficulty breathing
  • Faintness and dizziness
  • Swollen tongue and issues with speaking or swallowing
  • Tight chest
  • Collapsing and losing consciousness

If a person experiences anaphylaxis an ambulance must be called.

How do you treat a sulphur dioxide allergy?

A sulphur dioxide allergy is best treated by checking ingredients and avoiding foods and drinks that contain sulphur dioxide and/or sulphites.

If an anaphylactic reaction occurs an AAI (Adrenaline Auto-Injector also known as an 'epi pen') should be administered and 999 called. Many people with a sulphur dioxide allergy or intolerance find using an inhaler helpful.

What’s an alternative for sulphur dioxide?

There have been several experimentations with sulphur dioxide alternatives in the past, including ascorbic acid, but there are not many sulphur dioxide substitutes.

How can I avoid sulphur dioxide?

To truly avoid sulphur dioxide and sulphites you must avoid food and drinks that may contain them.

Unlike the majority of allergens, there is no protein or DNA able to be extracted from sulphur dioxide/sulphites, so checking for their presence in products requires analytical chemistry.

Since food and drinks containing sulphur dioxide and sulphites must declare that they do so, checking labels is the best way to check for their presence.

Is sulphur dioxide one of the 14 major food allergens?

Sulphur dioxide (sulphites) is one of the 14 major food allergens.

This means that pre-packed food sold in the UK, and the rest of the European Union, must clearly indicate on the label if it contains sulphur dioxide or sulphites at levels above 10mg per kg or per litre.

The other major food allergens are

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