Comparative incidence of side effects of a wax-matrix and a sustained-release iron preparation.

The side effects of a wax-matrix iron preparation and a sustained-release iron preparation were compared in a single-blind study of 181 subjects. Evaluations after four and eight weeks of therapy revealed moderate or severe side effects in 52% of the subjects who received the sustained-release preparation but in only 25% of those who received the wax-matrix preparation. Further analysis of the data demonstrated fewer side effects overall among patients who received the wax-matrix preparation. These findings suggest that the wax-matrix preparation is better tolerated than the sustained-release preparation.