Red, sore skin under the nappy (diaper). What it is and what to do.
Updated May 2026
What's probably happening
Nappy rash at this age is almost always one of two things, and the look tells them apart.
Irritant rash (most common). Red, sometimes shiny patches on the skin that touches wee or poo — bottom, lower belly, top of the thighs. The skin folds (creases) are usually spared. Caused by prolonged contact with moisture and stool acids.
Yeast (thrush) rash. Bright red or beefy patches that go into the skin folds, often with small red spots or pustules at the edges (satellite lesions). Doesn't improve with standard barrier cream over 2–3 days. More common after a course of antibiotics.
A pink area that fades within an hour of a clean dry nappy is irritation, not a rash to treat. Most newborn rashes clear in 2–3 days with the basics below.
When to escalate
See a doctor when you can:
No improvement after 2–3 days of frequent changes, barrier cream, and air time.
The rash is mainly in the skin folds with red spots at the edges (yeast pattern).
The rash spreads beyond the nappy area, or there are similar red patches in the mouth (oral thrush).
Get immediate medical care:
Skin is broken, blistering, weeping, or bleeding.
Yellow crusts, pus, or spreading red streaks beyond the nappy area.
Fever > 38°C in a baby under 3 months.
The full page also covers: exactly what to do right now, what not to change tonight, and how to adjust tomorrow if it happens again.