Could You Be Allergic to Additives in Food or Drugs?

When Kammy Eisenberg broke out in hives last December, she attributed it to stress. But the rash persisted, and Ms. Eisenberg was covered in hives “from head to toe” for eight months.

“It was everywhere,” said Ms. Eisenberg, 52, who lives in Atlanta. “I was beyond itchy.” Even powerful drugs like prednisone provided only moderate relief, she said. “My allergist was at a loss.”

She eventually consulted Dr. Robert Swerlick, an Emory University dermatologist known to take on difficult cases, who reviewed her medical record and suggested that since she was allergic to sulfa drugs, she might also be sensitive to dyes used to color medications.

Within days, Ms. Eisenberg switched her anti-allergy pills, which contained two blue dyes, even though they looked white, to a dye-free brand.

“The day after I switched, I was 90 percent better,” Ms. Eisenberg said, adding, “I was swallowing my problem by the handful every day.”

Doctors disagree on whether food additives like dyes, preservatives, stabilizers, emulsifiers and other substances can provoke a true allergic reaction. Medical journals have published case reports of allergic responses to food additives, including anaphylaxis, a potentially life-threatening reaction that causes the throat to constrict. But many allergists say such reactions are extremely rare, noting that the reports are anecdotal and that rigorous double-blinded studies have not found evidence that allergies to food additives exist.

“It’s very, very rare to see hives from a chemical that’s a food additive, because these are small molecules that typically don’t trigger allergic reactions,” said Dr. Scott Sicherer, a professor of pediatrics, allergy and immunology at Icahn School of Medicine at Mount Sinai. “No one’s saying it doesn’t happen, but the reports in the literature are handfuls — they’re not in the thousands.”

In 1986, however, after more than a dozen deaths were linked to severe allergic reactions to sulfite preservatives used to prevent green vegetables from turning brown, the Food and Drug Administration banned restaurants from using sulfites on raw fruits and vegetables.

The agency also requires foods containing yellow dye No. 5 to list the color on the label, saying the dye can cause hives in rare cases, estimated at “fewer than one in 10,000 people.”

In recent years, however, as consumer demand for natural foods has risen, food manufacturers have been replacing synthetic additives with natural ones derived from plants, insects and other animal products. These natural substances are more likely to provoke an allergic reaction because they contain proteins that our immune systems might react to, said Dr. Ronald Simon, an allergist and immunologist at Scripps Clinic Carmel Valley in San Diego, who reviewed the literature for UpToDate, a clinical information resource used by doctors.