Brief answer: Some Jains avoid brushing teeth in certain fasting periods to reduce harm (himsa) to tiny organisms in the mouth. Practices vary by tradition and vow, and many follow their guru’s guidance. In general:

• For normal days: brushing with care is allowed.
• During upvas, Athai, or very strict fasts: many observe brushing with minimal or no toothpaste, or avoid brushing at night, to prevent swallowing and to minimize harm to micro-organisms. Some communities may prefer rinsing with water or using herbal sticks instead.

Important note:

• The exact practice can differ between Digambar and Śvetāmbar traditions and from one guru/samāj to another. Always follow your own guru or samāj’s specific guidance.

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