Hello, With reference to your query, the oral medication of metronidazole should be taken as per your doctor's direction. You can't take more of it or longer than advised or ordered. The tablet can be taken with or without food. If it upsets your stomach, it is better to take it with meals. If it is an extended release tablet then it must be taken without food, one hour before or two hours after a meal and swallow the tablet. Do not break or crush or chew. You must complete the full course to clean up your infection, even if you begin to feel better. If you stop too soon, your infection may return. This medicine works best when there is a constant amount in the blood, so do not miss any dose and also take it at evenly spaced times during the day after consulting your doctor. Do not take metronidazole along with disulfiram that will have serious untoward side effects. Regarding the dosage, I am not sure what for you are taking Metronidazole and dosage depends on the type of infections like amoebiasis infections or bacterial infections or trichomaniasis infections or bacterial vaginitis and so on. If you miss a dose take it as soon as possible. Do not double doses. If you have any problem please contact your G.P. for further advice. Thank you.