Autoimmune haemolytic anaemia and mefenamic acid therapy

Three patients developed autoimmune haemolytic anaemia while being treated with mefenamic acid. In each case the autoimmune haemolytic anaemia was of the warm antibody gammaG type, and the antibodies had some rhesus specificity. All three patients recovered when the drug was withdrawn.Attempts to inhibit or enhance the activity of the antibody in vitro were unsuccessful.Direct antihuman globulin tests were made in.the red cells of 36 patients receiving long-term mefenamic acid therapy, but only one was found to be transitorily positive.