Sulfites are chemical preservatives used in a range of foods including beverages such as wine and beer. They are added to processed foods to increase their shelf-life and even to some medications to keep them stable. Sulfites can trigger allergic reactions in some people, mainly those having asthma. Sulfite-sensitive people often experience allergic reactions similar to those with food allergies.
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Symptoms of sulfite allergy
Symptoms of sulfite allergy can be mild to moderate and very rarely severe. Major symptoms of sulfite-sensitivity include the following:
- Digestive symptoms - diarrhea, stomach cramps, vomiting, and nausea
- Skin symptoms - red and itchy skin, rashes, and hives
- Respiratory symptoms - wheezing, difficulty breathing, cough, chest tightness
- Anxiety, paleness, and weakness
- Anaphylactic shock - very rarely, a severe and fatal allergic reaction can cause low BP and extreme difficulty to breath, which might lead to loss of consciousness.
Foods and medications containing sulfites
Sulfites are present in foods such as Parmesan cheese, mushrooms, and some fermented foods. Preserved food and drinks such as wine, cider, beer, sausages, soft drinks, burgers, and dried fruits are usually high in sulfites. Sulfite might be hidden in salad dressings in the form of vinegar or bottled lemon juice, in pizzas that use processed tomato sauce, and in olives, sausages, and sauces.
Fresh fruits and vegetables, fresh meat and fish, fresh dairy and freshly prepared sauces and dressings are generally considered free of sulfites.
Sulfites are also added to many drugs - both over-the-counter and prescription drugs. It may be present in drugs prescribed for vomiting and nausea, antibiotics, psychotropic drugs, cardiovascular drugs, IV medications, medications for respiratory problems, pain relievers, steroids, and anesthetics.
Sulfite in air
Apart from foods and drugs, polluted air can be a source of sulfite too. Levels of sulfur dioxide can be very high in the air in the vicinity of oil and coal-burning plants and in polluted air on foggy days. Exposure to sulfur dioxide in the air can lead to bronchoconstriction even in normal individuals. In asthmatic individuals, even very brief exposure to sulfur dioxide can cause severe bronchoconstriction.
Diagnosis and treatment of sulfite allergy
Sulfite hypersensitivity is usually diagnosed using food exclusion and reintroduction. This method involves the removal of sulfite-containing foods for a period of time. These foods are gradually re-introduced to see the reaction they might trigger.
Sulfite sensitivity is also diagnosed using a food challenge. This involves ingesting a very small amount of sulfite while the subject is under observation and close supervision by an allergist. In case there is no reaction, the amount of sulfite is slowly increased till a safe exposure level is reached. In case of any reaction, medication is given to reverse the symptoms.
A skin prick test is also used to diagnose sensitivity to sulfites. Here the allergen is placed on the skin surface and a prick is made in that area. If there is any skin reaction such as bumps, that can be indicative of sulfite sensitivity.
The only solution for a sulfite allergy is avoiding the specific allergen, sulfite. Sulfite-sensitive people should avoid foods with high levels of sulfite such as dry fruits, beer, wine, and processed foods. In order to avoid sulfite-containing foods, carefully reading product labels is very important. Ingredients to look for on food labels are potassium bisulfite, sulfur dioxide, sodium bisulfite, potassium metabisulfite, sodium metabisulfite, and sodium sulfite. People having asthma should be extremely careful with foods containing sulfite.
Anaphylactic reactions as a result of sulfite ingestion will need immediate emergency treatment including an epinephrine injection, followed by other procedures and observation at the hospital. People with high levels of sulfite sensitivity must carry epinephrine with them all the time.
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Further Reading
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