RESUMO
BACKGROUND: We did a prospective study in Atlanta, Georgia, during 1991 on the rate of systemic reactions caused by immunotherapy in a clinic that uses aqueous allergen extracts. METHODS: Immunotherapy reactions were monitored. Symptoms were recorded with respect to time of onset, involvement of respiratory tract or skin, and presence of hypotension. RESULTS: There were 98 systemic reactions in 96 patients (1 per 1600 visits or 1 per 47 patients). There was no direct relationship to seasonal pollen counts. There was, however, a correlation with the August to October increase in mold counts. There was no correlation between reactions and the age of the patient or the age of the extract. Patients were more likely to experience a reaction during the buildup phase than during maintenance therapy. The time of onset and the severity of the reaction were in agreement with previous reports. Severe reactions that included hypotension all occurred less than 30 minutes after the injection. In contrast to previous reports, patients with asthma were not at higher risk for a systemic reaction. CONCLUSION: Immunotherapy has a significant but low rate of systemic reaction. Potentially serious reactions may be mitigated by taking extra precautions during the earlier phases of an immunotherapy program and during seasons when mold counts are high.