Answer
Covonia Catarrh Relief Formula should be avoided with metronidazole because it contains alcohol, which is known to interact with metronidazole.
Sources for this answer
- Covonia Catarrh Relief Formula / Natures Aid Herbal Catarrh Relief FormulaThornton & Ross Ltd · emc · SmPC §4.5 Interaction with other medicinal products · Version 6Document updated
Sources checked