Serious adverse effects induced by simultaneous administration of two nonsteroidal anti-inflammatory drugs.

We have described the case of a 58-year-old woman in whom acute hemolytic anemia, renal failure, and granulocytopenia developed after intake of mefenamic acid and diclofenac. Results of direct and indirect Coombs' tests were negative, but the lymphocyte transformation test was positive for these two nonsteroidal antiinflammatory drugs (NSAIDs). We suggest that the immune complex mechanism could have induced these adverse reactions. Although these drugs are very popular, simultaneous administration should be avoided because serious adverse effects can potentially occur.