# First Aid 2025 → 2026: Every Change, System by System

> Page-by-page audit of the 367 differences between First Aid for the USMLE Step 1 2025 and 2026 editions, sorted by system.

URL: https://vault-guides.vercel.app/2025-vs-2026.html
Canonical: https://vault-guides.vercel.app/2025-vs-2026.html

## Summary

A change audit comparing First Aid for the USMLE Step 1 2025 and 2026 editions, covering 367 total changes mapped to 2026 page numbers. The breakdown is 160 new content items, 100 rewritten, 23 deleted, 84 page shifts and 5 corrections. Changes are grouped by system with per-system counts and page ranges, and each entry shows the 2025 text, the 2026 text, and why it matters for the exam. The page displays 77 of the 367 changes as a sample; the remaining 290 are in the Vault.

## Key facts

- 367 total changes between FA 2025 and FA 2026: 160 new content, 100 rewritten, 23 deleted, 84 page shifts, 5 corrections
- Per-system change counts include Cardiovascular 52, Neurology & Special Senses 36, Public Health Sciences 35, Biochemistry 33, Respiratory 26, Immunology 23, Renal 9
- Page ranges given per system, e.g. Biochemistry pp. 34–92, Immunology pp. 96–115, Microbiology pp. 126–200, General Pathology pp. 202–225, Respiratory pp. 684–706
- FA 2025 factual correction: kwashiorkor ADH changed from decreased to increased antidiuretic hormone (p. 69)
- Brand-new FA 2026 entries include bare lymphocyte syndrome (p. 98), peripheral tolerance (p. 101), AGEP as a SCARs entity (p. 111), ferroptosis (p. 203), GnRH pulsatility (p. 654), COPD triple therapy (p. 706), sotatercept for PAH (p. 706)
- The page shows 77 of the 367 changes; the other 290 sit inside the Vault

## Covers

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## Source

USMLE Vault — https://usmlevault.com
Author: Dr. Marish Asudani

Updated: 2026-08-26