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Heat Rash... don’t sweat it!

With warmer and humid weather, we may experience a rash called "heat rash".


What is a heat rash?

A heat rash is a common skin condition in which the opening of the pores and sweat ducts are blocked. When the pores are blocked, this prevents sweat made by the eccrine ducts (i.e. sweat producing ducts) from being excreted. This causes a cascade of events leading ultimately to inflammation in the top layer in the skin causing red bumps and dryness. A prickly heat rash is also referred to as militia rubra.


What causes a heat rash?

There are a few different clinical scenarios where we may develop a heat rash. Most commonly it occurs after being in a hot, humid environment for >10 minutes. Individuals may develop a heat rash as a result of a fever, after intense physical activity and as a result of prolonged bed rest (especially in those who are hospitalized or in a nursing facility with minimal mobility. Less commonly, a heat rash may occur in newborns as a result of immature sweat ducts that results in the inability to sweat; this may be as a result of a genetic disease. In individuals with a history of recurrent or persistent heat rashes, it may be a side effect of certain medications including isotretinoin and certain class of chemotherapy treatment and/or radiation.



What is the best treatment?

Though irritating and frustrating, a heat rash most of the time is not dangerous to one’s overall health and does not increase one’s risk of skin cancer, in contrast to a sunburn. It is important to take note if you experience a heat rash, it is our body’s way to telling us something important. I always say that our skin is a window to our internal health and we should not dismiss or ignore any skin findings.


In patients experiencing a heat rash, I stress the importance of moving to an air-conditioned area for at least 2-3 hours —avoiding excessive heat and humidity is essential in reducing sweating and avoiding skin irritation. Sleeping in a ventilated, cool bedroom, wearing loose clothing with breathable fabric can be very helpful to prevent worsening and help alleviate the skin rash.


Apply cool compresses to the skin may also help relieve discomfort. In those with persistent itching and skin irritation, mixing over-the-counter hydrocortisone with petroleum or vaseline and applying it to the affected areas on the skin twice daily can further help itching and skin inflammation. A bonus tip is putting any moisturizers and/or topical steroids in the refrigerator prior to application as the cooling sensation will help relieve discomfort and burning.


In individuals with a fever and a heat rash, it is important to contact your primary care physician and dermatologist for further guidance. Antipyretics such as acetaminophen can be helpful in controlling one’s fever and in turn help alleviate the heat rash.


If you experience a persistent rash, pustules and/or worsening redness despite the above mentioned measures, it is important to contact your provider for further evaluation to rule out persistent infection and/or underlying skin disease.




Montgomery  Dermatology, LLC

Phone (610) 265-1166

FAX (610) 265-1186

860 1st Ave #8b, King of Prussia, PA 19406
10000 Shannondell Drive, Audubon, PA 19403

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