When topical application: side effects are not identified. In some cases, allergic reactions and local reactions are possible.
The side effects associated with systemic absorption of metronidazole include: allergic reactions (rarely), leukopenia, ataxia, changes in the psyche (anxiety, lability of mood), convulsions; rarely: diarrhea, constipation, dizziness, headache, loss of appetite, nausea, vomiting, pain and abdominal cramps, change in taste (rarely), dry mouth, metallic or unpleasant aftertaste, increased fatigue.