What do sulphites do to the human body? Understanding sulfite sensitivity

January 4, 2026 •

4 min read

An estimated 3 to 10% of people with asthma may experience adverse reactions to sulphites. While most people tolerate them without issue, sulphites can cause a range of allergy-like symptoms and sensitivities in vulnerable individuals, impacting respiratory, gastrointestinal, and dermatological health.

Quick Summary

Sulphites can trigger allergy-like reactions, particularly in sensitive individuals and asthmatics, causing symptoms like wheezing, hives, and gastrointestinal upset. They are common food preservatives, but the precise mechanism of sensitivity is still under investigation.

Key Points

Sulphite Reactions are a Sensitivity, Not a True Allergy: Sulphite reactions do not typically involve the immune system in the same way as a true allergy, but cause similar symptoms.
Sulphites Exacerbate Asthma: Asthmatics are at higher risk of sensitivity, with reactions often including wheezing, coughing, and chest tightness.
Mechanism Involves $SO_2$ Gas Release: One primary theory suggests that sulphites release sulfur dioxide gas in the stomach, which can then irritate airways and trigger respiratory issues.
Label Reading is Critical for Management: Many countries require sulphites to be listed on food labels by name or E-number codes (E220-E228), which is key for avoidance.
Sulphites are Ubiquitous in Processed Foods: They are commonly found in wines, dried fruits, soft drinks, and many other processed and canned foods.
Diagnosis Requires Clinical Supervision: There are no reliable blood or skin tests for sulphite sensitivity; diagnosis typically involves a supervised food challenge.

What are sulphites?

Sulphites are a group of sulfur-based substances, including sulfur dioxide ($SO_2$), sodium sulphite, and potassium metabisulphite, used as preservatives and antioxidants in food, beverages, and pharmaceuticals. This helps to prevent discoloration and microbial growth, extending product shelf-life. While naturally occurring in some foods like fermented items, a significant portion of human exposure comes from added sulphites. This is why they are found in a wide range of processed goods and beverages, such as dried fruits, wine, beer, and some processed meats.

How sulphites affect the human body

For the majority of the population, consuming sulphites poses no known health risk. The body has mechanisms, including the enzyme sulphite oxidase, to metabolize and excrete them harmlessly. However, for a segment of the population, a sensitivity or intolerance to sulphites can trigger a variety of adverse reactions. This is not a true allergy involving an IgE immune response, but a different physiological mechanism.

Mechanisms of sulphite sensitivity

Several theories attempt to explain why some individuals react negatively to sulphites:

Sulfur Dioxide Gas Release: It is thought that in the acidic environment of the stomach, sulphites release sulfur dioxide gas. This gas can be inhaled and irritate the airways, leading to respiratory symptoms.
Enzyme Deficiency: Some individuals with low levels of the enzyme sulphite oxidase may struggle to properly break down sulphites, leading to an accumulation in the body that can cause adverse effects.
Histamine Release: Sulphites may trigger the release of chemicals like histamine, which can cause allergy-like symptoms such as hives and swelling.
Neurological Effects: There is speculation that sulphites may affect the parasympathetic nervous system, leading to bronchoconstriction, though more research is needed.

Symptoms of sulphite sensitivity

Reactions can vary widely among sensitive individuals, from mild to severe. Symptoms can appear within minutes to hours after exposure and affect multiple bodily systems.

Respiratory symptoms

Wheezing
Tightness in the chest
Coughing
Shortness of breath

Skin reactions

Hives (urticaria)
Itching or redness
Worsening of pre-existing eczema

Gastrointestinal issues

Abdominal pain or cramping
Nausea and vomiting
Diarrhoea

Other potential symptoms

Headaches and migraines
Heart palpitations
Joint pain (though more research is needed)

In rare cases, sulphites have been linked to anaphylaxis, a severe, potentially life-threatening allergic reaction, particularly in highly sensitive individuals.

High-sulphite food and drink comparison

To manage sulphite sensitivity, it is essential to be aware of which products contain high levels of these preservatives. Here is a comparison of common food items.


Food/Drink Category	Common Examples	Sulphite Concentration	Notes
Wine	White wines, sweet wines	High (up to 400 mg/L)	Red wines generally contain less; organic wines have stricter limits.
Dried Fruits	Apricots, raisins, prunes	High	Sulphites prevent browning and spoilage.
Processed Meats	Sausages, minced meat	Variable to high	Can be used to inhibit bacterial growth.
Soft Drinks/Juices	Some cordials, fruit juices	Moderate to high	Used as a preservative to maintain freshness.
Canned Vegetables	Potatoes	Moderate	Prevents discoloration and extends shelf-life.
Beer	Most commercial beers	Moderate	Used for stabilization and preservation.
Fresh Produce (often)*	Salads in restaurants	Variable	Can be illegally added to keep fresh produce looking vibrant.

*In many countries, it is illegal to add sulphites to fresh produce sold unpackaged.

Managing sulphite sensitivity

Effective management primarily involves avoidance of sulphite-containing products. For some, reducing intake is sufficient, while others with more severe sensitivities must be scrupulous about avoiding all traces.

Label checking and codes

In many regions, food manufacturers are required by law to declare the presence of sulphites on product labels if the concentration is above a certain threshold (e.g., 10 mg/L). Look for sulphites listed by name or by their E-number codes (E220-E228).

Medical consultation

If you suspect you have a sulphite sensitivity, it is vital to consult a healthcare professional, especially if symptoms are severe or impact your breathing. They can help confirm the sensitivity through food challenges under controlled supervision, as standard allergy tests may not detect it. It is important to distinguish sulphite sensitivity from a true sulphonamide antibiotic allergy, as they are different conditions.

Conclusion

While a common and generally harmless food preservative for most, sulphites pose a genuine health risk for sensitive individuals, especially those with asthma. The effects can range from mild skin irritations to life-threatening respiratory reactions. Understanding what do sulphites do to the human body and identifying high-risk foods is crucial for managing symptoms and maintaining health. Consulting with a medical professional is the recommended course of action for anyone experiencing adverse reactions, as it is key to a proper diagnosis and management plan.

For more detailed information on food allergies and sensitivities, visit the official website of the Australasian Society of Clinical Immunology and Allergy (ASCIA) [https://www.allergy.org.au/patients/other-allergy/sulfite-sensitivity].

Frequently Asked Questions

No, sulphite sensitivity is completely different from an allergy to sulphonamide antibiotics. They are different chemical substances and people with a sulphite sensitivity do not need to avoid sulphonamide drugs.

Some reports have linked sulphites to an increase in migraine headaches in sensitive individuals, though further research is needed to fully investigate the causal link.

Wines, especially white and sweet wines, are often high in added sulphites. Dried fruits like apricots and raisins also contain high levels of these preservatives.

To avoid sulphites, you must carefully read food and drink labels. Look for the ingredient listed as 'sulphites' or its E-number codes (E220–E228). Avoiding processed foods and dining out less frequently can also help.

Yes, adverse reactions to sulphites have been reported in children, particularly those with chronic asthma, who may be at a greater risk of sensitivity.

Though extremely rare, severe allergic-like reactions, including anaphylaxis, have been reported in highly sensitive individuals following sulphite exposure.

Sulphite oxidase is an enzyme in the body that helps to metabolize and break down sulphites into harmless sulfates. A deficiency in this enzyme may contribute to sulphite sensitivity.