Rash risk rises when the heat is on


With summer approaching and warmer weather to look forward to, a downside is the potential for a skin issue related to higher temperatures.

Apart from sunburn, heat rash is another condition that can be unique to this warmer season, as it’s more likely to happen when the body sweats. It’s also sometimes called prickly heat or sweat rash. Although harmless, it can be very itchy, causing small red spots where sweat collects, such as the armpits, groin, elbow creases, back of the knees and under the breasts.

According to Harvard University heat rash can also be an initial sign that the body needs to cool down. It can be important to address a heat rash before other heat related illnesses take hold. Sustained exposure to high heat can lead to heat exhaustion and heat stroke.

With the Climate Council predicting El Nino conditions to bring high heat and a dry summer for Australia, some preparation and prevention measures would be wise.


The good news is that symptoms of heat rash are usually short lived, lasting about two to three days. Cleveland Clinic reports that it can spread on the body, through the clogged sweat pathways, but doesn’t spread from person to person.  Cleveland Clinic

Symptoms include tiny red spots or clear blisters, an irritating itch and prickling sensation and redness and mild swelling in the affected area. For babies, these symptoms often appear in the skin folds, on their face or in the nappy area.

Occasionally, the fluid filled sacs of heat rash can become inflamed and pus-filled, potentially leading to an infection.


Heat rash is usually caused by excessive sweating, with the sweat glands getting blocked. According to Cleveland Clinic the body reacts to the clog and attempts to heal it by creating inflammation that forms a rash.

It’s common in babies as their sweat glands haven’t developed properly yet. It can also happen in older children. It can strike adults who may be bedridden, with sweat and heat accumulating underneath them, or anyone sleeping with too many blankets or layers on.

According to the Australasian College of Dermatologists, heat rash is diagnosed by a doctor often based on the typical appearance of the lesions, through diagnostic tests in rupturing the blister to assess the sweat, a biopsy, or a skin swab to rule out secondary infection.


Heat rash can normally get better without treatment. However, in the meantime, the key is to keep the skin cool and dry to avoid sweating and irritation of the rash. Some avoidance measures that can be taken include drinking plenty of water to prevent dehydration, staying out of heat and humidity, and remaining in an air-conditioned environment or near a fan.

Clothing to wear should be loose and made of cotton, with fabrics such as wool, synthetics or scratchy material that can irritate the skin to be avoided. For babies and children, clothes and nappies should be changed regularly.

To soothe the itching or prickly sensations, applying something cold to the area my help, such as a damp cloth or ice pack (wrapped in a tea towel) for up to 20 minutes.

Avoid scratching the area, as this could lead to the bumps on the skin breaking open easily, and possibly to an infection, according to Cleveland Clinic. It’s best to tap or pat the rash instead of scratching it, and avoid use of perfumed skin care products.

A cool bath or shower may help bring short-term relief from any itching, but excessive showering or bathing should be avoided as this can strip the body of its natural oils that protect the skin, and may make it worse. Children should avoid soaps.

Over-the-counter pharmacy products to relieve the symptoms of itching include calamine lotion and antihistamine tablets. Harvard University recommends against using baby powder, or oily or greasy moisturisers, as these can further block sweat ducts. The International Hyperhidrosis Society points to aloe vera as a good choice.

Low strength hydrocortisone cream is also an option to treat the inflammation, although this is not suitable for children under 10 or pregnant women unless they’ve seen a doctor first about this.

Role of pharmacists

Apart from recommending OTC products, pharmacists could look out for signs that a referral to a GP may be required.

“Pharmacists can play a really important role in this space, by identifying if the skin condition is indeed heat rash and no other conditions that may present similar symptoms, such as dermatitis, eczema or fungal infection,” said Dr Vincent Candrawinata, health and wellness expert and founder of Renovatio Bioscience. “Identifying the condition ensures proper treatments.

“Pharmacists should ask questions regarding how long the symptoms have presented, if there are any accompanying symptoms, or history of skin issues.”

Bianca Laver is a clinical educator and aesthetician who added: “If a rash is more severe, a pharmacist should encourage a patient to see their healthcare provider or a [dermatologist] to be sure it’s heat rash and not another skin disorder.”

Questions to ask the patient include:

  • How long have you had the rash?
  • What could have caused this rash?
  • Is this a repeated issue, and if so, what variables usually precede the heat rash?
  • Have there been any changes in environment or new routines?

The patient may need to see a GP if the rash doesn’t improve after a few days, or their baby has a rash they’re concerned about.

Other indications a patient may need to see a doctor include:

  • The blisters fill with pus.
  • The area is getting red and swollen, or feels warm.
  • If the patient is feeling unwell or has a fever.
  • If there are swollen lymph nodes.

Antiseptics and antibiotics may be recommended if a secondary infection is suspected.

According to the Australasian College of Dermatologists, when a large surface area of the body is affected, patients can develop a high temperature and suffer from heat stress syndrome.

Heat stress results from a loss of water and salt in the body. It can come from excessive sweating without adequate salt and fluid replacement. Heat exhaustion occurs when the body is unable to cool itself properly and, if left untreated, can progress to heat stroke.

Heat stroke is the most serious heat-related illness, according to the National Institute for Occupational Safety and Health. It occurs when the body can no longer control its temperature: the body’s temperature rises rapidly, unable to cool down and the sweating mechanism fails. Body temperature can rise to 41.1°C or higher within 10 to 15 minutes. Heat stroke can cause permanent disability or death if the person doesn’t receive emergency treatment.





By Tracey Cheung. 

First published in Retail Pharmacy November

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