Sulfites are commonly found in various foods and drugs. “Sulfites” is the general name for six specific substances, which are: sulfur dioxide, sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite, and potassium metabisulfite.

As additives, sulfites can prevent spoilage of food. They prevent the growth of mold and bacteria, they can stop fruits, vegetables, and seafood from discoloring, and maintain the strength of common medications, including some asthma drugs. 

They can be added to foods and beverages such as apple cider and other types of cider, avocado dip, beer and wine, jams, gravies, molasses, dried fruits and vegetables, peeled potatoes, shrimps, and shellfish. Sulfites also occur naturally in foods including asparagus, chives, cornstarch, eggs, fish such as salmon and dried cod, garlic, leeks, lettuce, and tomatoes, among others.

According to federal law, sulfites cannot be added to any food that can be eaten raw such as fruits and vegetables. However, when sulfites are used as preservative, they must be listed as an ingredient.

Symptoms

Symptoms of sulfite allergy can vary but the most common include itchy hives, upset stomach, dizziness, and respiratory difficulties. The combination of asthma and sulfites can be dangerous because it can lead to anaphylactic shock, where in the airways can swell shut, making it difficult to breathe. 

Diagnosis

A doctor can tell if you have sulfite allergy with a test called a controlled sulfite challenge. The patient is then exposed to a small amount of sulfites under close supervision to monitor if there’s any reaction. 

Prevention Tips

• Read labels and check for sulfite substances 
• When eating out, ask the waiter or waitress if the food contains sulfites
• If you have asthma, check with your doctor to make sure that the asthma drugs you use do not contain sulfites
• If you have a known allergy to sulfites, always carry an inhaler and an epi-pen with you