Short answer: During Paryushan/Das‑Lakshan, Jains intensify ahimsa, restraint, and simplicity. Avoiding shaving is a practical way to reduce himsa and vanity, and to stay focused on sadhana.

Why not shave during Paryushan

• Ahimsa and carefulness (samiti): Shaving can cause cuts/bleeding and destroys countless minute beings associated with the skin, water, and lather. In these days we minimize all avoidable violence.
• Sanyam and tyag: Grooming the body (shave/trim/style) feeds attachment, pride, and concern for appearance. We practice letting go and keep life very simple.
• Anukarana (following the ascetic ideal): Monks practice kesh‑lochana (plucking). Householders emulate that spirit by not cutting hair/nails during this holy period.
• Shauch and internal purity: Less external beautification, more time for pratikraman, svadhyaya, dhyan, and kshamapana.

Digambar and Shvetambar notes

• Shvetambar: Paryushan is 8 days; avoiding shaving, haircuts, nail‑cutting, perfumes, and adornment is commonly observed as a householder vrata.
• Digambar: Das‑Lakshan is 10 days; the same heightened restraint and simplicity apply. The intention is the same—reduce parigraha and himsa.

If unavoidable due to work or health

• Do it before the festival begins, or postpone till it ends.
• If you must, keep it minimal and careful, in daylight, with full awareness; then do alochana/pratikraman.

For a simple overview of Paryushan/Das‑Lakshan and the dos/don’ts, see:

• What is Paryushan
• Dos and don’ts in Paryushan
• Das‑Lakshan details