A sulfite used as a preservative and antioxidant in foods and drinks.
Some people are sensitive to sulfites and can have serious reactions to them ranging from wheezing to potentially life-threatening anaphylactic reactions. As a result, sulfites should be avoided by anyone with a sulfite allergy or sensitivity. People with asthma have between a 1 in 20 to 1 in 100 chance to having a sulfite reaction.
Sulphur dioxide in foods and beverages: its use as a preservative and its effect on asthmahttps://pubmed.ncbi.nlm.nih.gov/7426352/