A person can develop sulfite sensitivity (allergy) at any point in their life but the cause is often unknown. Sulfites are sulfur-based compounds that are added by food manufacturers and restaurants for many purposes such as reducing discoloration of light-colored fruits and vegetables; preventing black spots on seafood; inhibiting the growth of microorganisms in fermented foods such as wine; conditioning dough; maintaining the stability and potency of certain medications. The most common symptom is difficulty in breathing. Sulfites give off the gas sulfur dioxide, which can cause irritation in the lungs and cause a severe asthma attack for those who suffer from asthma. Responses vary; sulfites can also cause chest tightness, nausea, hives, or even anaphylactic shock.