Among the published studies some have specifically sought to define the pattern of adverse effects. In one such study, although a single dose of the drug was combined in some patients with diethylcarbamazine, the adverse effect pattern was similar to that when ivermectin was used alone. There now seem to be some circumstances in which a single low dose of ivermectin is sufficient to have a prolonged effect, for example in loaiasis a dose of 150 micrograms/kg resulted in a very much reduced level of microfilaria as much as a year later, and seemed to eliminate the infestation entirely in more than half the users. If further work confirms the validity of this approach, the adverse reactions problem may be lessened, since at these doses the few reactions experienced were limited to the skin and joints, although some calabar-like swellings were also noted.