Nitrate anaphylaxis.

BACKGROUND

Nitrate and nitrite salts are commonly used to preserve and sustain color in a number of processed meats. To date there have been no described cases of anaphylaxis to either nitrates or nitrites in the literature.

OBJECTIVE

We report a patient with anaphylaxis to nitrates and nitrites documented by double-blind, placebo-controlled capsule challenge.

METHODS

A 22-year-old previously well male, presented to a tertiary referral center with a 4-year history of recurrent anaphylaxis after eating take-out food. No further episodes occurred while adhering to a strict elimination diet. We performed a double-blind, placebo-controlled capsule challenge both with food substances and starch placebo. These occurred in a hospital setting with full resuscitative procedures available.

RESULTS

An acute anaphylactic reaction occurred following a challenge to nitrates and nitrites. Generalized allergic reactions were observed on separate occasions following administration of artificial colorings and metabisulfite. There was a mild urticarial reaction following salicylates. He was placed on a diet free of sulfites, nitrates, nitrites, and low in salicylates and he has had no further reactions. A computer based search of the Medline, Current Contents and EMBASE databases found no previously reported cases of urticaria, angioedema, or anaphylaxis to either nitrates or nitrites.

CONCLUSION

The ingestion of processed meats containing nitrate or nitrite salts may be associated with angioedema and anaphylaxis and should be considered when investigating patients with suspected food allergy.