Prolonged maintenance interval in hymenoptera venom immunotherapy.

To decrease the cost, inconvenience, and potential side effects of venom immunotherapy we tested whether the interval between the maintenance injections can be increased. In 30 patients who had been given the standard therapy regimen and who had been sting-challenged after 1 and 2 yr of monthly maintenance injections the maintenance interval was increased from 4 to 6 wk. IgG anti-yellow jacket venom antibodies did not change over the next 9 mo. The incidence of local reactions to venom injections did not increase, and there were no systemic reactions during therapy. After 6 to 9 mo 29 of the 30 patients were sting-challenged with one possible reaction. The success rate, 97%, is the same as that observed with monthly maintenance injections. We conclude that the 6-wk maintenance interval is effective in both clinical and immunologic terms after a period of monthly maintenance therapy.