Heat Rash (Prickly Heat) in Babies
Medically reviewed by Dr. Sarah Chen, MD, FAAP · Board-Certified Pediatrician
Content reviewed against published AAP, NIH, AAP guidelines
Last reviewed:
Baby skin is sensitive and changes frequently. If you are noticing heat rash (prickly heat) in babies, here is what you need to know.
The short answer
Heat rash, also called prickly heat or miliaria, occurs when sweat glands become blocked and sweat gets trapped under the skin. It appears as tiny red or pink bumps, often in skin folds and areas covered by clothing. Heat rash is very common in babies because their sweat glands are still maturing, and it typically clears up on its own once the baby is cooled down.
Key takeaways
- Heat rash, also called prickly heat or miliaria, occurs when sweat glands become blocked and sweat gets trapped under the skin. It appears as tiny red or pink bumps, often in skin folds and areas covered by clothing. Heat rash is very common in babies because their sweat glands are still maturing, and it typically clears up on its own once the baby is cooled down.
- Usually normal when: Tiny red or pink bumps in skin folds, on the neck, chest, or areas covered by clothing that appear in warm conditions
- Call your doctor if: The bumps develop pus, the surrounding skin becomes increasingly red and warm, or your baby develops a fever, which could indicate a secondary skin infection
- Varies by age — see the age-by-age breakdown below
“Eczema is very common in babies and children. About 1 in 10 children will develop eczema, typically starting in the first few months of life.”
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What Parents Should Know
According to AAP, NIH guidelines, heat rash, also called prickly heat or miliaria, occurs when sweat glands become blocked and sweat gets trapped under the skin. It appears as tiny red or pink bumps, often in skin folds and areas covered by clothing. Heat rash is very common in babies because their sweat glands are still maturing, and it typically clears up on its own once the baby is cooled down. At 0-3 months, newborns are especially prone to heat rash because their sweat glands are not fully developed. The rash often appears on the neck, face, chest, and diaper area. It can also occur in cooler weather if a baby is overdressed or swaddled too warmly. The general rule is to dress your baby in one layer more than you are comfortable in, but watch for signs of overheating like sweating, flushed skin, or fussiness. It is generally considered normal when tiny red or pink bumps in skin folds, on the neck, chest, or areas covered by clothing that appear in warm conditions. However, you should contact your pediatrician promptly if the bumps develop pus, the surrounding skin becomes increasingly red and warm, or your baby develops a fever, which could indicate a secondary skin infection.
Normal vs. Concerning
By Age
What to expect by age
0-3 months
Newborns are especially prone to heat rash because their sweat glands are not fully developed. The rash often appears on the neck, face, chest, and diaper area. It can also occur in cooler weather if a baby is overdressed or swaddled too warmly. The general rule is to dress your baby in one layer more than you are comfortable in, but watch for signs of overheating like sweating, flushed skin, or fussiness.
3-6 months
Heat rash commonly appears in skin folds such as the neck creases, behind the ears, in the elbow creases, and in the groin area where moisture accumulates. Keeping these areas dry and exposed to air can help. Avoid heavy creams or lotions on affected areas, as these can further block sweat glands. A cool bath without soap and lightweight, breathable clothing are the best treatments.
6-12 months
As babies become more active, they generate more body heat and are more likely to develop heat rash during warm weather or active play. The rash may appear on the back, chest, and areas under a car seat or carrier where airflow is restricted. Remove your baby from the heat source, cool the skin, and the rash should fade within hours to a day or two.
12-24 months
Active toddlers running and playing in warm weather may develop heat rash on the back, chest, and in skin folds. While the condition is less common as sweat glands mature, it can still occur when toddlers are overdressed or in hot, humid environments. Continue to dress your toddler in lightweight, breathable fabrics and ensure they have access to shade and cool water.
What to Tell Your Pediatrician
- Describe when you first noticed heat rash (prickly heat) in babies and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if the rash does not improve after 2-3 days of cooling measures and keeping the area dry.
- Mention if your baby seems uncomfortable or is scratching at the rash persistently.
- Bring a list of any questions or observations you want to discuss at the appointment.
What Should You Do?
When to take action
- Tiny red or pink bumps in skin folds, on the neck, chest, or areas covered by clothing that appear in warm conditions
- The rash fades and resolves within hours to a couple of days after cooling the baby down
- Your baby does not seem bothered by the rash or is only mildly fussy
- The bumps are small and uniform without any blisters, pus, or spreading redness
- The rash does not improve after 2-3 days of cooling measures and keeping the area dry
- Your baby seems uncomfortable or is scratching at the rash persistently
- You are having difficulty distinguishing heat rash from eczema, a viral rash, or another skin condition
- The rash recurs frequently despite efforts to keep your baby cool and appropriately dressed
- The bumps develop pus, the surrounding skin becomes increasingly red and warm, or your baby develops a fever, which could indicate a secondary skin infection
- Your baby shows signs of heat exhaustion or heatstroke such as very hot skin, lethargy, vomiting, or decreased responsiveness -- seek emergency care immediately
What You Can Do at Home
- Keep track of when you notice heat rash (prickly heat) in babies — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that tiny red or pink bumps in skin folds, on the neck, chest, or areas covered by clothing that appear in warm conditions — this is generally within the range of normal.
- At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
- Use fragrance-free, hypoallergenic products on your baby's skin. Avoid over-bathing — 2-3 baths per week is usually sufficient.
- While monitoring at home, seek immediate care if the bumps develop pus, the surrounding skin becomes increasingly red and warm, or your baby develops a fever, which could indicate a secondary skin infection.
Related Resources
Rash Decision Tree
Identify common rashes and determine when to seek care.
Baby Skin Conditions Guide
Visual guide to common baby skin conditions, rashes, and when to see a doctor.
Month-by-Month Development
Detailed monthly development guides from birth through 24 months.
When to Call the Doctor
General guide on when to call the pediatrician, visit urgent care, or go to the ER.
Frequently asked questions
Is heat rash (prickly heat) in babies normal?
When should I call the doctor about heat rash (prickly heat) in babies?
When is heat rash (prickly heat) in babies normal?
What causes heat rash (prickly heat) in babies?
What should I mention to my pediatrician about heat rash (prickly heat) in babies?
Is heat rash (prickly heat) in babies normal at 0-3 months?
Is heat rash (prickly heat) in babies normal at 3-6 months?
Should I go to the ER for heat rash (prickly heat) in babies?
Does heat rash (prickly heat) in babies go away on its own?
References
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Heat Rash (Prickly Heat) in Babies.
Things to mention
- Describe when you first noticed heat rash (prickly heat) in babies and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if the rash does not improve after 2-3 days of cooling measures and keeping the area dry.
- Mention if your baby seems uncomfortable or is scratching at the rash persistently.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- The rash does not improve after 2-3 days of cooling measures and keeping the area dry
- Your baby seems uncomfortable or is scratching at the rash persistently
- You are having difficulty distinguishing heat rash from eczema, a viral rash, or another skin condition
Urgent signs to report immediately
- The bumps develop pus, the surrounding skin becomes increasingly red and warm, or your baby develops a fever, which could indicate a secondary skin infection
- Your baby shows signs of heat exhaustion or heatstroke such as very hot skin, lethargy, vomiting, or decreased responsiveness -- seek emergency care immediately
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members
Related Resources
Bottom line
Most cases of heat rash (prickly heat) in babies are normal. Talk to your pediatrician if the bumps develop pus, the surrounding skin becomes increasingly red and warm, or your baby develops a fever, which could indicate a secondary skin infection.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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