Short answer: It is best to avoid cutting hair, beard, and nails during Paryushan.

Why:

• Ahimsa: Cutting and shaving involve subtle himsa (harm to tiny living beings). Paryushan is a time to reduce all forms of violence and carefulness is increased.
• Sanyam and Aparigraha: We practice restraint and simplicity, avoiding grooming for beauty or display.
• Tradition: Both Śvetāmbara (8 days, ending on Samvatsari) and Digambara (Daśalakṣaṇa, 10 days) traditions encourage extra self‑discipline; householders commonly refrain from haircuts, shaving, and nail‑cutting during this period.

Practical guidance:

• If possible, do necessary grooming before Paryushan begins.
• If there is a genuine medical or hygiene need that cannot wait, keep it minimal and do pratikraman for any lapse in restraint.

For a simple overview of Paryushan/Daśalakṣaṇa and its purpose:

• Śrāvaka focus in Paryushan:
• Digambara Daśalakṣaṇa Parva basics: