I get white tongue coating when taking flagyl. any way to prevent?

Need more info: 1) How often, and why, are you taking flagyl? 2) Do you get similar white coating or discharge on other mucus membranes, such as the vagina or anus? 3) Have you been treated for oral thrush, with any anti-fungal medicines, like clotrimazole or nystatin? Rarely, persistent oral thrush can indicate HIV infection (AIDS). See a doctor to get a quick painless test to rule out this possibility.