The Causes and Risk Factors for Heat Rash, Prickly Heat and Miliaria
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The Causes and Risk Factors for Heat Rash, Prickly Heat and Miliaria

The causes and risk factors for heat rash, prickly heat and miliaria

It is summer here in Montreal and it is important to know that heat rash or prickly heat is not only common to people in tropics it happens here in Montreal, to babies and adults alike.

Causes for heat rash

The main cause of heat rash is that your sweat ducts have become clogged with debris and instead of sweating out, the perspiration remains trapped inside the skin, causing a rash and inflammation. Though it is not for certain exactly what causes the blocking here are some of the leading causes.

In babies

The sweat ducts are not fully mature and they rupture causing the perspiration to remain inside. This happens when a baby is overheated due to the weather or due to wearing too much clothing, or heavy clothing. It can also happen if the infant is in an incubator or is running a high fever.

In adults

Tropical climates

Whether you live in the tropics or you are experiencing Montreal's hot humid summers you can be a candidate for heat rash, prickly heat or miliaria.


Exercise, hard work or any physical activity that causes you to perspire can result in a bout of miliaira.


People can get heat rash even in the winter if they bundle up too much. Sometimes sleeping with an electric blanket will cause heat rash as well.


Certain fabrics that do not leave room for normal perspiration can cause heat rashes. Avoid polyester fabric and stick to cottons that will breathe.


Being confined to a bed with a fever can cause a heat rash.

Heavy creams, lotions and ointments

Although lotions may be soothing, reduce generalized pain, or moisturize dry skin, they can also clog the sweet ducts and cause heat rash.

Drugs and Medication

The chemotherapy drug doxorubicin (Adriamycin), the ADHD medication clonidine (Catapres), which is also a high blood pressure medication, isotretinoin (Accutane) an acne fighting drug, and bethanechol (Urecholine) which is given for bladder infections are among the drugs that can bring on heat rashes.

Basically we can sum up the risk factors for getting a heat rash as follows.

as being an infant.

living in a tropical country.

hot and humid weather anywhere in the world.

Wearing too much clothing or clothing that is tight fitting and prevents your skin from breathing.

having a fever or being bedridden.

Living in a really hot house with out a fan or air conditioner.

certain medications creams and ointments.



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Comments (6)

Expert medical insight into these conditions. Thanks, Carol.

Thanks Carol for this informative series.

thanks Ron

WEll done health skin article about the causes of prickly heat and heat rashes.Promoted

Returning with a well deserved vote up.

thanks roberta