Sulfites are food additives. Though sulfites are considered safe, they pose a risk to asthma patients who take steroid medication. Asthma patients on steroid medication can have sensitivity to sulfites. Potassium and sodium bisulfites can cause constriction of the airways in people with asthma.

Sulfites include sulfur dioxide, sodium sulfite, and both the bisulfites and metabisulfites of sodium and potassium. Found in a variety of food products and medications, sulfites serve various functions. Sulfites prevent oxidation and browning of light-colored fruits and vegetables such as apples and potatoes and prevent decomposition of food products by hindering the growth of bacteria.

Sulfites preserve flavor and prevent spoilage. Sulfites are also used to condition dough and bleach food starches in baked goods. In medication, sulfites are used to maintain potency. Sulfites prevent the development of black spots on shrimp and lobster. In wine and other fermenting beverages, sulfites control microbial growth. Sulfites are often found in dried fruit, dried vegetables, bottled lemon juice, bottled lime juice, pickled foods, and various other foods. The use of sulfites is relatively common, so people with sulfite sensitivity need to read food labels to know if the food contains sulfites.

It is estimated that five percent of all people with asthma are sensitive to sulfites. Up to twenty percent of children with asthma who take steroid asthma medication are sensitive to sulfites. Sulfite sensitivity occurs more often in women than in men. Sulfite sensitivity can range from mild to life-threatening. The sensitivity to sulfite has been found to be linked to the inherited hypersensitivity to the immune system.

Sulfites are present in some medications for asthma. The reaction of sulfites increases with higher doses of the medication containing sulfites. If an asthma patient reacts to sulfites, the patient should avoid future consumption of sulfite-containing products. In accordance with the United States Food & Drug Administration (FDA), the presence of sulfites must be disclosed on food labels. If foods sold in bulk or unpackaged have been treated with sulfites, a sign must be posted that discloses the presence of sulfites.

When a steroid-dependent asthma patient consumes sulfites, if they have sulfite sensitivity, they may feel irritation of the throat. The sulfite may cause other asthma symptoms and could cause the airway to constrict. A severe asthma attack could result. People with asthma who take steroids are encouraged to read food labels for the presence of sulfites. People who are at risk of a sulfite-induced asthma attack should take their inhalers with them if they go out to eat.