Erythrosine is a tetraiodofluoresceine-resembling eosine used as a food and drug colorant. It belongs to the azoic-class of coloring agents, is soluble in water, binds strongly to serum proteins in vitro and presents little toxicity while supplying a high level of iodine.
Clinical manifestations
General: anaphylactic shock, serum sickness.
Cutaneous: chronic urticaria, photosensitization, angioedema.
Respiratory: asthma.
E.N.T.: chronic rhinitis.
Diagnostic methods
Cutaneous testing.
Intradermal skin-test using an aqueous solution at a concentration of 1.5 mg/ml give positive results in 35 to 70% of patients with immediate or delayed reactions to erythrosine.
Precipitating antibodies in patients with serum sickness.
Detection of IgE antibodies by RAST is successful in 70% of patients with immediate reactions.
Re-challenge with surveillance of target organ:
Immediate IgE-mediated hypersensitivity is involved in most cases (immediate positive skin tests, detection of specific IgE antibodies).
Immune complex-mediated hypersensitivity has been implicated in patients with serum sickness.
Value of challenge tests in conjunction with RAST and skin test.
For cutaneous manifestations, an elimination diet of several weeks, followed by reintroduction of the coloring agent in capsule form gives clear and irrefutable results.


  1. Vesely B, Bodmer R, Guerin B, Girard J.P, "Manifestations cliniques à l’erythrosine. Etude du rôle des mécanismes d’hypersensibilité", Rev. fr. Allergol., 1985; 1 (25) 7-11.

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.