Heat Rash (Miliaria) in Newborns
The short answer
Heat rash (miliaria) in newborns appears as tiny red bumps or clear blisters, usually in skin folds, on the face, neck, chest, or areas covered by clothing. It occurs when sweat glands become blocked from overheating or overdressing. It is harmless and resolves quickly once baby is cooled down.
This is one of the most common questions parents ask. Searching for answers means you care.
By Age
What to expect by age
Newborns are prone to heat rash because their sweat glands are immature. The rash appears as tiny red bumps (miliaria rubra) or tiny clear blisters (miliaria crystallina) in areas where sweat is trapped: neck folds, chest, back, diaper area, and anywhere clothing is tight. Treatment is simple: cool your baby down, remove excess clothing, and move to a cooler environment. Avoid heavy creams or lotions that can block pores. Dress your baby in one layer more than you would wear, not multiple extra layers.
Heat rash remains common during this period. As you learn your baby's temperature regulation needs, you will become better at dressing them appropriately. The rash resolves within hours to a day once overheating is addressed. Keep the nursery at a comfortable temperature (68-72F).
Heat rash may occur during warmer months or when babies are overdressed. The same cooling measures apply. Avoid direct sun exposure and dress your baby in light, breathable fabrics.
As your baby becomes more active, heat rash may occur in areas of increased friction or sweating. Continue to dress appropriately for the temperature and keep skin folds dry.
What Should You Do?
When to take action
- Tiny red bumps or clear blisters in skin folds or under clothing that appear during warm weather or overdressing
- Rash resolves quickly (within hours) after cooling down
- Baby is not bothered by the rash
- No spreading redness, pus, or fever
- Heat rash does not resolve within a day or two after cooling measures
- The rash looks different from typical heat rash (spreading, raised, painful)
- You are unsure whether the rash is heat rash or something else
- Rash accompanied by fever, which could indicate infection rather than heat rash
- Signs of overheating: hot to touch, rapid breathing, lethargy, or unresponsiveness
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Skin Concerns
Overdressing and Overheating Baby
Overdressing and overheating are common concerns and a risk factor for SIDS. Dress your baby in one layer more than you would wear comfortably. Signs of overheating include sweating, damp hair, flushed cheeks, heat rash, and rapid breathing. Check your baby's chest or back of neck to gauge temperature.
Ideal Room Temperature for Baby
The ideal room temperature for a sleeping baby is between 68-72 degrees F (20-22 degrees C). A room that is too warm increases the risk of SIDS. Dress your baby in one layer more than you would wear comfortably, and check their chest or back of neck to assess temperature rather than hands or feet.
Erythema Toxicum (Red Blotchy Rash in Newborns)
Erythema toxicum is a very common, completely harmless rash that appears in up to 50% of full-term newborns, usually within the first 2-5 days of life. It looks like red blotches with small yellow or white bumps and can appear anywhere on the body except the palms and soles. It resolves on its own without any treatment.
Baby Acne vs Eczema: How to Tell the Difference
Baby acne and eczema can both cause facial rashes, but they look and feel different. Baby acne appears as small red or white bumps, similar to teenage acne, usually on the cheeks, nose, and forehead. Eczema causes dry, rough, red, itchy patches. Baby acne resolves on its own by 3 to 4 months, while eczema may need ongoing management.
Baby Acne (Neonatal Acne)
Baby acne is a very common, harmless condition that appears as small red or white bumps on your newborn's face, usually around 2-4 weeks of age. It is caused by maternal hormones still circulating in your baby's system and clears up on its own within a few weeks to months without any treatment.
Alopecia Areata in Babies
Alopecia areata is an autoimmune condition where the immune system attacks hair follicles, causing round, smooth patches of hair loss. While uncommon in babies, it can occur at any age. The condition is not painful or contagious. Many children experience spontaneous hair regrowth, though it may take months. Your pediatrician or dermatologist can confirm the diagnosis.