Metabisulfite sensitivity is being described with growing frequency.
Sulfites are used in food, drinks, and drugs. Adverse reactions to apparently nontoxic doses have been described. Exposure of sensitive persons to
sulfites has produced
asthma, and occasionally other adverse reactions in nonasthmatic patients. We present a case of
urticaria induced by metabisulfites. During the previous 2 years the patient had suffered episodes of
urticaria and
angioedema limited to the face, neck, upper thorax, and
dysphonia without
asthma after the ingestion of food and drinks containing
sulfites. Oral challenge with 25 mg of
potassium metabisulfite elicited
urticaria on the face and neck, nasal
itching,
rhinorrhea, and
dysphonia. Prick and intradermal tests were negative. Two further challenges with the same doses were also positive. One of these was controlled with placebo, 30 minutes after
oral administration of 400 mg
sodium cromolyn; the second was carried out 90 minutes after
oral administration of 5000 micrograms
cyanocobalamin. We have been unable to identify a pathogenic mechanism.