What Causes Heat Rash in Adults? How to Treat It?

Heat rash, medically known as miliaria, is very common in warm and humid climates. Although children and infants are more susceptible to miliaria, it can affect people of all ages and genders (1). There are a few main causes that cause heat rash in adults. Depending on its type, this type of rash can be inflammatory or non-inflammatory. In this article, we discuss the causes, types, and symptoms of this issue, along with the heat rash treatment and management options available for adults. Keep reading!

  • What Is Heat Rash?
  • Causes Of Heat Rash
  • Different Types Of Heat Rash (Miliaria)
  • Symptoms Of Heat Rash
  • Heat Rash In Adults
  • Diagnosis Of Heat Rash
  • Treatment And Management Options
  • Frequently Asked Questions

What Is Heat Rash?

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Heat rash is known by many names, such as eccrine miliaria, prickly heat, and sweat rash. It is a common skin issue that occurs when the eccrine sweat glands and ducts are blocked (1).

The eccrine sweat glands produce a majority of the body’s sweat. These glands can be found in the skin all over the body. When these sweat glands are blocked, the sweat produced is sent back into the dermis or epidermis layer of the skin. This causes a heat rash under the skin.

Prickly heat causes discomfort, nocturnal restlessness, and daily irritation (2). It can also lead to serious medical issues like impetigo, folliculitis, and furunculosis.

This condition is most commonly noticed during summer and is associated with a high fever. So what causes the eccrine glands in the skin to clog? There are three main causes that you can learn about in the next section.

Causes Of Heat Rash

Type 1 Pseudohypoaldosteronism is a condition where excessive amounts of sodium are released from the body, leading to its deficiency. One of the ways sodium is released is through the sweat glands. This condition has been associated with a type of miliaria known as rubra (1).

A rare autosomal recessive disease known as Morvan syndrome also leads to hyperhidrosis (excessive sweating), which may cause heat rash (1).

Certain medications can cause your body to sweat excessively, leading to heat rash. Bethanechol, clonidine, and neostigmine have been known to cause miliaria. In some cases, isotretinoin may also cause heat rash (1).

Bacteria like Staphylococcus epidermidis may cause blockages in the eccrine glands. These bacteria form biofilms that clog the glands, causing sweat to seep into the epidermis or dermis. This leads to overhydration, swelling, and further blockage of ducts. If left unmanaged, it can lead to the rupture of these glands and ducts (1).

Tight clothes, strenuous physical activity, and drug patches may also cause blockages in the eccrine sweat glands. Excessive sweating leads to overhydration of the stratum corneum, which leads to blockages. Also, it is common to sweat excessively in hot and humid conditions (1).

Some ducts become dilated under pressure, leading to their eventual rupture, which causes sweat to clog the skin. In some cases, UV ray exposure may cause damage to epidermal cells, which leads to duct rupture (1).

All of these causes can lead to three different types of heat rash, namely miliaria crystallina, rubra, and profunda. Learn more about them in the next section.

Different Types Of Heat Rash (Miliaria)

Each of these types has specific characteristics or symptoms to help you distinguish between them. Keep reading to learn more about them.

Symptoms Of Heat Rash

Common symptoms to look out for include:

  • Excessive sweating
  • Clogged and sweaty skin
  • Itching
  • Sponge-like spaces on the skin
  • Sticky skin
  • Burning sensation
  • Blisters

Now that you know the causes and symptoms of heat rash, keep reading to learn how each of these types of heat rashes affects adults.

Heat Rash In Adults

Identifying miliaria requires a thorough clinical diagnosis. Find out how it is diagnosed in the next section.

Treatment And Management Options

Miliaria crystallina usually resolves on its own within 24 hours. And the miliaria rubra treatment focuses on reducing inflammation. Mild to mid-potency corticosteroids, like triamcinolone 0.1% cream, may be prescribed for one to two weeks (1).

Topical antibiotics, such as clindamycin, can treat any bacterial infections caused by miliaria pustulosa. The combined use of oral isotretinoin (40 mg per day) for 2 months and topical anhydrous lanolin may be effective in reducing miliaria profunda (1).

Besides these medical treatments, you can follow a few tips to treat and prevent heat rash:

  • This skin issue can be treated with antibiotic, antimicrobial, and steroidal agents (3). Topical lotions, powders, gels, and ointments (containing a cleaning agent) may also be used. The cleansing agent removes all impurities from the skin to prevent any clogging.
  • Soothing, anti-inflammatory, antipruritic, and cooling agents may also be prescribed.
  • Natural remedies like an oatmeal bath, aloe vera massage, baking soda paste, sandalwood powder, Fuller’s earth, margosa leaves, and gram flour can be used to soothe heat rash.
  • Miliaria rubra is generally reversible and responds immediately to cooling measures such as air conditioning, gentle breeze from a fan, or removal of excessive clothing.
  • Supplemental vitamin C may help restore normal sweating in stubborn cases.
  • Lightweight, soft cotton clothing is advisable for summer wear, as cotton is very absorbent and keeps moisture away from the skin.
  • Exfoliate the skin to remove any blocking substances such as sweat, dirt, and product residue.
  • Remove bandages or patches that could lead to sweat clogging. You should also treat febrile illnesses to prevent any risk of heat rashes.

Note: Topical agents such as powders, creams, and ointments (that are formulated for treating heat rash) are usually ineffective and may exacerbate a heat rash by keeping the skin warm and further occluding the pores.

Frequently Asked Questions

Does heat rash in adults go away on its own?

Yes. Heat rashes get better on their own within days. But, severe cases can last for several weeks in adults.

Can dehydration cause heat rash in adults?

Yes. Staying hydrated in hot environments and drinking plenty of water may help prevent heat rash in adults.

Is Vaseline good for heat rash in adults?

Yes. Vaseline helps relieve the discomfort caused by heat rash.