Heat rash in babies looks like tiny pink or red bumps — sometimes with small blisters — that appear on skin where sweat gets trapped: the neck, chest, diaper area, and skin folds. It is uncomfortable but not dangerous, and it usually clears up within a day or two once the skin is kept cool and dry. If the rash spreads, becomes painful to touch, or your baby develops a fever, that is when you call your pediatrician.
Known medically as miliaria, heat rash happens when a baby’s sweat glands become blocked. Babies are especially prone because their pores are small and their bodies cannot regulate temperature as efficiently as adults.
What Does Baby Heat Rash Look Like?
There are three types, each looking slightly different:
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- Miliaria crystallina — clear, superficial blisters that burst easily. Least uncomfortable.
- Miliaria rubra (the most common) — small red bumps with mild itching or prickling. Often called “prickly heat.”
- Miliaria profunda — deeper, flesh-colored bumps. Less common in infants.
How to Treat Heat Rash Fast
- Move your baby to a cool, air-conditioned space immediately
- Remove tight or extra layers of clothing
- Apply a cool, damp cloth gently to the affected area — do not rub
- Keep the skin dry; avoid heavy lotions or powders that can further block pores
- Dress your baby in loose, breathable cotton
Most cases resolve on their own within 24–48 hours without any treatment.
When Heat Rash Needs a Doctor
Call your pediatrician if:
- The rash does not improve within 3 days
- You notice swelling, warmth, or pus — signs of a secondary infection
- Your baby develops a fever or seems unusually uncomfortable
- The rash covers a large area of the body
