Doctor Q&A

Common Summer Skin Rashes in Kids Series: Heat Rash

This is a 3-week series with Dr. Robin Schaffran, M.D., a caring mom and Pediatric Dermatologist. She is a board-certified Dermatologist and attending staff physician at Cedars Sinai Medical Center. She attended the University of Toronto Medical School where she graduated as a member of the Alpha-Omega-Alpha Honors Medical Society.

Common Summer Children Skin Rashes with Dr Robin Schaffran Pediatric Dermatologist

Is Heat Rash in Kids due to Sweat, Clothes or Foods?

Heat rash is a common term, and in Asia, it may be thought of rashes that come out from consuming ‘heaty’ foods. Is that right? Let’s find out, with the help of Dr Robin.

Heat rash’s scientific term is Miliaria, also known as sweat rash or prickly rash. It is common during summer, especially if it’s hot and humid. It affects children especially due to their underdeveloped sweat glands, which are more prone to becoming blocked and therefore causing rash.

Can you explain to us the interaction of heat and sweat, and the glands that cause a rash in miliaria?

Dr Robin: Miiaria occurs under conditions of high heat and humidity that lead to excessive sweating. Occlusion of the skin from too much clothing or blankets can aggravate the pooling of sweat on the skin surface leading to overhydration of the skin. In susceptible persons such as infants who have immature sweat glands, this often leads to transient blockage of the sweat ducts. Therefore, as more sweat is produced, there becomes and inability to secrete the sweat because of the blockage. This results in the appearance of a rash called miliaria.

What is Child Eczema is Triggered by Rash?

MarcieMom: For a child with eczema whose eczema is triggered by sweat, what is the difference between atopic (to sweat?) versus a heat rash?

Dr Robin: Eczema is an inflammation of the skin, usually genetic, which is often aggravated by sweat and looks completely different than the appearance of miliaria. Eczema triggered by sweat looks like eczema triggered by any other trigger. Miliaria (heat rash) on the other hand, looks like small, tiny red bumps or vesicles which is usually asymptomatic.

Appearance of Heat Rash

Heat rash looks like dots or tiny pimples, and usually doesn’t require medical attention.

MarcieMom: Dr Robin, can you share with us where are the common body parts where heat rash occur? Is it more likely to be inside clothing due to heat trapped from wearing too much?

Dr Robin: The most common area of involvement for heat rash is the trunk area because of occlusion from clothing and blankets.

Treatment of Heat Rash

MarcieMom: When will heat rash require seeing a doctor?

Dr Robin: Heat rash is usually self limiting and asymptomatic so there is no reason to treat it. The reason to see a doctor is to ensure that the eruption is indeed heat rash and not something else that would require treatment.

MarcieMom: How should heat rash be treated at home?

I’ve read that calamine lotion can be applied to sooth the irritability but will that be drying for the skin (thus not suitable for a child with eczema)?

Dr Robin: The mainstay of managing heat rash involves controlling heat and humidity so that sweating is not stimulated. Measures include removing occlusive clothing, limiting activity or providing air conditioning. Topical treatments involve lotions containing calamine and menthol and are for soothing purposes only and are not necessary. They can be drying to the skin and would not recommended to a patient with eczema.

Calamine and Menthol can be Drying for Eczema Skin

Does Drinking Water help with Heat Rash?

MarcieMom: Drinking water is important in hot weather to prevent dehydration. Does drinking more water help prevent heat rash?

Dr Robin: Drinking water is important for hydration but heat rash is not a result of dehydration so drinking more water would have no effect on preventing heat rash.

MarcieMom: Thank you Dr Robin, your reply helps parents understand more about heat rash, and next week, we will be covering insect bites.

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