Here is a simple, Jain-dharma–aligned way to manage pitta (acidity/heat) while doing upvas.

Before you take the vow (pachkhan)

• Choose tapa according to your capacity. If you have pitta issues, prefer Tivihar Upvas (only boiled water in day) or Ekashan/Ayambil instead of nir-jal upvas. This is apramatta (careful) tapa and fully within Jain maryada.
• On the previous day, eat light, non‑spicy, non‑sour food (plain rice, plain moong, soft khichdi, a little ghee if customary). Sleep early.

During upvas

• Shwetambar tradition: If you are doing Tivihar/Upvas with water, take only boiled and cooled water, in small sips, only between sunrise and sunset. Avoid large gulps.
• Digambar tradition: Classical upvas is nir‑jal (no water). If pitta is severe, you may adopt a milder vow (e.g., Tivihar or Ekashan) with proper pachkhan rather than harming the body.
• Keep the body cool and calm:

- Stay out of direct sun/heat; keep the room ventilated. - Maintain inner shanti: do Navkar mantra, kayotsarg, and samayik. Calm mind reduces “inner heat.”

• Avoid triggers: no tasting, smelling food intentionally, or thinking about recipes. Rest more; speak less to conserve ojas.
• Signs to be careful about: burning in chest, dizziness, blackouts, persistent vomiting. If these appear, end the fast properly (parna) without delay and inform your guru/elder.

Parna (breaking the fast) — gentle and pitta‑soothing

• First, take lukewarm boiled water in small sips.
• Then take very light, non‑spicy, non‑sour, easily digestible items:

- Rice kanji (thin rice water), moong water, or plain soft khichdi (no chili/garam masala; very mild or tasteless). - Avoid fried, sour (lemon, tomato), chili, very hot‑temperature, or very cold items.

• Eat slowly, in small quantity. Maintain maun (silence) if possible.

Building capacity (longer-term)

• Do regular, gentle tapas like Ayambil to reduce raga‑dvesha and stabilize digestion without irritating pitta.
• Keep daily ahar simple and timely; avoid late dinners and excessive spices.

Important maryada notes

• Water rules differ:

- Shwetambar: In Tivihar/Upvas with water, only boiled water in daylight; after sunset, nothing. - Digambar: Classical upvas is without water. If health demands, take an appropriate, lighter vow with pachkhan rather than forcing nir‑jal.

• Tapa must be apramatta (careful), not self‑harming. Preserving the body as an instrument for sadhana is praised in Jain Dharma.

Health caution

• If you have chronic acidity, ulcers, are pregnant, elderly, or on medication, avoid nir‑jal. Do Tivihar/Ekashan/Ayambil with guidance, and take parna at the first sign of distress.