Heat rash occurs in adults and children when the body sweats more than usual.
It is more common during the summer months or in hot, dry climates.
This article will cover what heat rash looks like, finding immediate relief, prevention, and more.
COROIMAGE / Getty Images
COROIMAGE / Getty Images
How Does Heat Rash Look?
Heat rash can be identified by skin location and appearance.
The most common symptoms are itching and small bumps in the affected skin area.
Reproduced with permission from ©DermNetdermnetnz.org2023.
In people with lighter skin tones, these bumps may appear red.
In people with darker skin tones, they may appear darker than the surrounding skin.
This photo contains content that some people may find graphic or disturbing.
Reproduced with permission from ©DermNetdermnetnz.org2023.
Reproduced with permission from DermNetdermnetnz.org2023.
Location
Heat rash can present in different ways and on different skin areas.
It is sparked by blockage and inflammation of the eccrine sweat ducts.
Heat rash is sometimes divided into three categories based on the level of blockage of the sweat ducts.
Categories are:
Onset of Symptoms
Symptoms of heat rash typically come quickly.
The rash will appear within minutes to hours of excessive sweating.
Sweating is the body’s response to heat and is intended to cool.
When sweat leaves the pores of the skin, it evaporates and takes body heat with it.
If the skin’s ducts become clogged, sweat cannot reach the surface and evaporate.
It will become trapped and can cause heat rash.
Miliaria crystallina presents as a clear or skin-colored heat rash.The rash will present with fluid-filled bumps on the skin.
It can affect up to 9% of newborns.
Pustules can be painful or become infected.
Miliaria profunda sometimes presents with large, firm skin bumps when exposed to heat.
It can also cause systemic symptoms like nausea and dizziness.
Skin Tone Presentation
Heat rash can present differently on different skin tones.
The difference is due to the amount of melanin in the skin.
Melanin is the substance that gives hair, skin, and eyes their color (pigment).
Sensations
Heat rash can be uncomfortable, and some types are more painful than others.
Extreme itch is a symptom of the most painful key in of heat rash, miliaria profunda.
If it causes pustules, the pus-filled bumps may become inflamed and swollen.
Heat Exhaustion
Heat rash can sometimes be present along withheat exhaustion.
With heat exhaustion, the body is exposed to high temperatures and not enough fluids.
Symptoms of heat rash include:
Is It a Heat Rash or a Skin Allergy?
Hives typically present in more than one body area, whereas a heat rash appears in one affected area.
If your child’s rash gets worse or if they develop afever, seek immediate medical attention.
A severe rash may require over-the-counter (OTC) treatments.
Fortunately, it is preventable.
Heat rash can affect anyone, including infants and children.
Cooling down and wearing loose, lightweight clothing can help manage heat rash.
Heat rash is a preventable condition.
Harvard Health Publishing.Heat rash: how to spot it and what to do.
Seattle Children’s HospitalHeat rash.
DermNet.Heat rash (miliaria): images, causes, and treatment.
Chadha A, Jahnke M.Common neonatal rashes.Pediatr Ann.
2019;48(1):e16-e22.
2020;24(2):374-382. doi:10.4103/jomfp.JOMFP_207_20
MedlinePlus.gov.Heat illness.
DermNet.Acute generalised exanthematous pustulosis (AGEP): treatment, images, and causes.
Yale Medicine.Grover’s disease.
World Health Organization.Herpes simplex virus.
Mount Sinai.Erythema toxicum Information.
2015;14(1):43-48.
DermNet.Aloe vera and the skin.
