This handout is for hypersensitivity pneumonitis (acute + chronic-fibrotic). Your care team identified this based on: subacute/chronic exertional dyspnea + dry cough with a compatible antigen exposure (ats/jrs/alat 2020).
Other reasons your team may use this plan: recurrent influenza-like episodes (fever/chills/myalgia/cough) 4–8 h after antigen exposure (watts/grammer 2019 pmid 31690386); inspiratory crackles ± inspiratory squeaks/squawks ± weight loss (ats/jrs/alat 2020); hrct mosaic attenuation / air-trapping / three-density (headcheese) sign / centrilobular ggo nodules ± fibrosis (ats/jrs/alat 2020).
Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.
| Medication | Starting dose | How | When | What it does |
|---|---|---|---|---|
| antigen identification + complete avoidance/remediation | identify culprit antigen (structured questionnaire ± serum IgG) then COMPLETE removal/remediation — remove birds/feather/down bedding, mold remediation, stop hot-tub/humidifier, MWF/isocyanate engineering controls or work restriction | n/a | permanent; verified at every visit | ATS/JRS/ALAT 2020 (PMID 32706311) — antigen identification + avoidance is the CORNERSTONE and the only intervention with a survival signal; unidentified antigen confers worse prognosis. Co-manage with occupational/environmental medicine; re-exposure = treatment failure |
| prednisone | 0.5–1 mg/kg/day PO (commonly ~40–60 mg/day) for acute/inflammatory nonfibrotic HP; taper over weeks–months guided by symptoms/PFT/HRCT response (taper documented here — `taper_plan` field does NOT exist in _types.ts) | PO | once daily then tapered | ATS/JRS/ALAT 2020 — corticosteroid gives acute symptomatic/functional benefit in inflammatory HP but limited long-term disease modification; avoidance remains primary. Taper (not abrupt stop): consolidate 4–8 wk at induction dose then step down over weeks–months with symptom/PFT/HRCT reassessment; monitor glucose/BP/bone/infection during taper |
| methylprednisolone | 500–1000 mg IV daily ×3 (pulse) then transition to oral prednisone taper for acute severe HP respiratory failure / AE-like fibrotic deterioration | IV | pulse ×3 then oral taper | Acute severe HP / AE-like fibrotic-HP deterioration — high-dose/pulse corticosteroid is common practice with limited controlled evidence; exclude and treat infection/PE/HF first; align ICU/ECMO escalation with transplant candidacy + goals of care (ATS/JRS/ALAT 2020; AE concept from Collard-type ILD-AE definition applied to fibrotic HP) |
| mycophenolate mofetil | 500 mg PO BID titrating to 1000–1500 mg BID as tolerated | PO | BID | ATS/JRS/ALAT 2020 — steroid-sparing immunosuppression for progressive inflammatory/chronic HP unresponsive to avoidance ± corticosteroid; stabilises lung function in observational cohorts. RxCUI 68149 (mycophenolate mofetil ingredient) NOT independently re-verified via RxNav this pass — see .depth.md §RxCUI-audit (verify-flag). CONTRAINDICATED in pregnancy (teratogen) → use azathioprine branch |
| azathioprine | 1 mg/kg/day PO, titrate to ~2–2.5 mg/kg/day (TPMT/NUDT15-informed) | PO | once daily | ATS/JRS/ALAT 2020 — alternative steroid-sparing agent; ~61% AZA-responder rate at 12 mo and BAL lymphocytosis predicts favourable response (OR 1.051, 95% CI 1.015–1.089; Raimundo 2021 PMID 33621590). Check TPMT/NUDT15 before start; CBC + LFT surveillance. RxCUI 1256 (azathioprine ingredient) NOT independently re-verified via RxNav this pass — see .depth.md §RxCUI-audit (verify-flag) |
| nintedanib | 150 mg PO BID (100 mg BID if hepatic impairment / poor tolerance) | PO | BID WITH FOOD | INBUILD HP subgroup (Wells Lancet Respir Med 2020 PMID 32145830): chronic-HP subgroup nintedanib vs placebo FVC-decline difference +73.1 mL/yr (95% CI -8.6 to 154.8); overall INBUILD progressive-fibrosing ILD annual FVC -80.8 vs -187.8 mL (Δ ~107 mL/yr; Flaherty NEJM 2019 PMID 31566307). RxCUI 1592737 confirmed correct in sibling pulm.idiopathic_pulmonary_fibrosis.v1 §RxCUI-audit 2026-05-16. Diarrhoea most common ADR; hepatotoxicity; bleeding/arterial-thromboembolic caution; CYP3A4/P-gp substrate; AVOID Child-Pugh B/C, reduce to 100 mg BID Child-Pugh A |
| oxygen | titrate to resting SpO2 ≥90%; ambulatory O2 for exertional desaturation | inhaled | continuous if resting SpO2 ≤88% | ATS/JRS/ALAT 2020 supportive — LTOT for resting hypoxemia; ambulatory O2 for isolated exertional desaturation in fibrotic HP |
| pulmonary rehabilitation | structured exercise + education program | n/a | program course; maintenance thereafter | Supportive — improves 6MWD, dyspnea, QoL in fibrotic ILD including fibrotic HP (extrapolated from ILD rehab evidence) |
| lung transplant referral | early referral for progressive fibrotic HP without absolute contraindication | n/a | one-time referral + ongoing co-management | Lung transplant is the only disease-modifying option for end-stage progressive fibrotic HP; refer early when progressive despite avoidance + immunosuppression ± antifibrotic (ISHLT candidate-selection principles; ATS/JRS/ALAT 2020) |
| nonfibrotic vs fibrotic phenotype routing (axis selector) | nonfibrotic → avoidance + corticosteroid ± steroid-sparing (often reversible); fibrotic → avoidance + (immunosuppression if inflammatory component) + ANTIFIBROTIC if progressive + transplant/palliative | n/a | at diagnosis + re-evaluated on progression | Special-pop branch: the ATS/JRS/ALAT 2020 nonfibrotic-vs-fibrotic dichotomy is the dominant therapeutic fork — nonfibrotic is inflammatory/often reversible (anti-inflammatory axis); fibrotic is UIP-like/progressive (antifibrotic axis, prognosis approaching IPF). Fibroblastic-foci profusion HR 2.36 (Chiba 2016 PMID 26836921) + traction-bronchiectasis HR 1.10 (Walsh 2012 PMID 22466512) gate aggressiveness |
| occupational / avoidable-antigen remediation + work restriction | environmental remediation + occupational-medicine referral; respirator/engineering controls; job modification or removal if remediation insufficient (farmer's lung, MWF, isocyanate, bird-handler) | n/a | until verified antigen-free | Special-pop branch: occupational/avoidable antigen — the highest-leverage actionable scenario; complete avoidance can arrest or reverse nonfibrotic HP. Verify remediation success at follow-up; partial avoidance often fails |
| unidentified-antigen strategy (empiric remediation + lower IS/antifibrotic threshold) | broad empiric environmental remediation (avian/mold/humidifier sweep) + lower threshold for steroid-sparing immunosuppression / antifibrotic + tighter FVC/DLCO surveillance | n/a | continuous | Special-pop branch: unidentified antigen confers WORSE survival (ATS/JRS/ALAT 2020) — cannot remove what is not found, so escalate pharmacologic disease modification earlier and surveil more closely |
| azathioprine (pregnancy — preferred steroid-sparing agent; AVOID mycophenolate) | 1 mg/kg/day titrating per tolerance (TPMT/NUDT15-informed); minimise corticosteroid; antifibrotic CONTRAINDICATED in pregnancy | PO | once daily | Special-pop branch: pregnancy — mycophenolate is teratogenic (contraindicated); azathioprine is the preferred steroid-sparing agent if immunosuppression needed; nintedanib contraindicated in pregnancy; minimise corticosteroid dose; co-manage with maternal-fetal medicine. RxCUI 1256 carries the same verify-flag (see .depth.md §RxCUI-audit) |
| nintedanib 100 mg BID (hepatic impairment — Child-Pugh A; AVOID Child-Pugh B/C) / IS renal-hepatic dose-modify | 100 mg PO BID (reduced) for Child-Pugh A; AZA/MMF dose-modify and intensify CBC/LFT in hepatic/renal impairment | PO | BID with food | Special-pop branch: hepatic/renal impairment — nintedanib reduce to 100 mg BID Child-Pugh A, NOT recommended Child-Pugh B/C (DailyMed label); azathioprine + mycophenolate require dose modification and intensified marrow/hepatic surveillance in hepatic/renal impairment |
Plan: HP antigen-avoidance + anti-inflammatory + steroid-sparing + antifibrotic — ATS/JRS/ALAT 2020
Contact your care team if any of the following happen:
Call 911 or go to the nearest emergency room right away if you have:
ILD clinic q3–6 mo, occupational/environmental-medicine continuity (verify successful remediation; home/workplace inspection; respirator/work-restriction adherence), transplant clinic co-management for progressive fibrotic HP, comorbidity sweep (Group-3 PH-ILD, lung-cancer surveillance in fibrotic HP, depression, GERD), pulmonary rehab continuity, palliative care + advance care planning for progressive fibrotic HP (ATS/JRS/ALAT 2020)
Guideline: ATS/JRS/ALAT 2020 Hypersensitivity Pneumonitis Diagnosis Guideline (Raghu AJRCCM 2020) + INBUILD progressive-fibrosing-ILD program (HP subgroup)