[en] Several classes of drugs can promote renal retention of lithium and, occasionally, can induce lithium intoxication. The antimicrobial agent metronidazole hydrochloride (Flagyl I.V.) was also implicated in producing such a reaction in one woman. The authors describe two patients who experienced toxic reactions to lithium following brief use of metronidazole. However, in these two patients, in contrast to the previous case, the degree of acute intoxication was less severe and treatment with metronidazole was completed without apparent suspicion, but persistent signs of renal damage later emerged