Immediate rhinoconjunctivitis induced by metamizole and metronidazole.

OBJECTIVE

To report a case of immediate rhinoconjunctivitis induced by both metamizole and metronidazole.

METHODS

Skin-tests (prick and intradermal) were performed with metamizole, metronidazole, and espyramicine. Standard RAST was carried out with metamizole and metronidazole. Oral challenge tests were performed single blind with Rhodogil, metronidazole, espyramicine, metamizole, aspirin, and propyfenazone.

RESULTS

Both skin tests and RAST were negative. We also found that the patient tolerated therapeutic doses of espyramicine, aspirin, and propyfenazone. Challenges with Rhodogil, metamizole, and metronidazole elicited immediate rhinoconjunctivitis.

CONCLUSION

This is an exceptional case of immediate rhinoconjunctivitis induced by two unrelated drugs (metamizole and metronidazole). The pathogenic mechanism implicated in this process remains unclear. Inhibition of the cyclooxygenase pathway was excluded and we could not demonstrate the presence of specific IgE antibodies. Nevertheless, an immunologic or idiosyncratic mechanism could be responsible.