Interactions
As mentioned above, metronidazole should not be combined with alcohol due to intolerance development. If the drugs barbiturates and phenytoin are administered at the same time, a faster degradation of metronidazole and a resulting reduction in the effect must be expected due to an enzyme acceleration. If blood thinners (anticoagulants) are combined with metronidazole, an interaction and an increased bleeding tendency must be expected. In the treatment of depression with lithium, there is a risk that the lithium level could rise dangerously high when combined with nitroimidazoles, causing corresponding side effects.
Contraindications
Metronidazole and similar preparations from the same group of substances should not be administered in the case of diseases of the central nervous system or the haematopoietic system as well as in the case of severe liver diseases, pregnancy and lactation.