Heat Rash vs Eczema: What Are the Differences?

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Heat rash and eczema are two skin conditions that cause a rash with bumps.

This article will discuss heat rash and eczema symptoms, causes, and treatment. It will also cover ways to prevent these two conditions.

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Symptoms

Heat rash and eczema have a few overlapping symptoms that make it tough to tell the two conditions apart. They both cause small fluid-filled skin bumps that can break open and release the fluid. They also cause redness and itching.

However, several symptoms separate the two conditions, as outlined below.

Heat Rash
  • Fine red rash with small fluid-filled bumps

  • Mild swelling

  • Itchy, prickling sensation

Eczema
  • Dry, scaly skin patches

  • Redness

  • Itching

  • Chronic eczema can cause skin thickening

Causes

Heat rash and eczema have two distinct causes. Identifying the cause can determine the type of rash, making treatment more successful.

Heat Rash

Heat rash is caused when sweat gets trapped under the skin. Sweat glands can get clogged or blocked, forcing the sweat down into the skin. Several different things can cause this:

  • Tight clothing
  • Sweat-inducing exercise
  • Medications that cause sweating like bethanechol, clonidine, and neostigmine
  • Hot and humid weather
  • Conditions that cause sweating like Morvan syndrome, which causes neurological symptoms
  • Anything that occludes the skin like bandages or medication patches

Children and infants are more at risk for heat rash because their sweat glands and pores can easily become blocked.

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This video has been medically reviewed by Casey Gallagher, MD

Eczema

Eczema is caused by the skin's inability to retain moisture. It can be brought on by genetics and is linked to asthma and allergies. Eczema can come and go, with certain triggers that cause flare-ups (times of increased symptoms). Triggers can include:

  • Stress
  • Temperature changes
  • Dry weather
  • Certain soaps or lotions
  • Food allergies
  • Wearing synthetic materials or wool

Diagnosis

Heat rash and eczema are diagnosed in similar ways. A healthcare provider will carefully examine the rash and ask health-history questions. A person's recent activities will help determine the type of rash.

Heat rash is often preceded by heat exposure or exercise. The location of the rash is also a helpful indicator of heat rash. If a healthcare provider is unsure, they may use a dermoscopy to examine the rash more closely. A skin punch biopsy (a way of acquiring tissue to be examined in a lab) can also be used to make a diagnosis.

Eczema can usually be diagnosed by its appearance. A healthcare provider may use a patch test to see if there are allergens on the skin. Another diagnostic tool is a skin biopsy, this would rule out other causes.

Treatment

Heat rash and eczema have different treatments, making a proper diagnosis crucial to getting the right treatment.

Heat Rash

A hot, humid environment often causes heat rash. Eliminating hot, humid conditions can help reduce sweating and heat rash. Other treatments include wearing breathable clothes, removing skin patches or bandages, and skin exfoliation.

Mild heat rash does not need treatment and typically resolves in 24 hours. If the rash is uncomfortable over-the-counter calamine lotion and cold washcloths can relieve symptoms.

Moderate heat rash is treated with steroid cream. Talk to a healthcare provider to determine if a prescription strength cream is necessary.

If the rash has become infected then an antibiotic may be necessary.

Eczema

Eczema is a chronic condition with no known cure. Treatments are focused on managing the symptoms and keeping the skin intact and moist.

Treatments for the symptoms of eczema can include:

  • Skin cream: Thick, barrier skin creams can help retain moisture
  • Steroid creams: Reduce itching and swelling
  • Antihistamines: Reduce itching
  • Oral steroid medication: Reduce itching and swelling
  • Antibiotics: Used if the skin has become infected from scratching
  • Phototherapy (light therapy): Can stop the body's response that causes inflammation
  • Immunosuppressants (like methotrexate and cyclosporine): Can suppress the immune system and can be used to reduce eczema flare-ups

Prevention

One of the best ways to manage heat rash and eczema is to prevent it from even happening. Here are ways to prevent these rashes.

Heat Rash

Not every incidence of heat rash can be prevented but there are several ways to reduce the likelihood of developing this itchy, painful rash.

  • Wear loose-fitting clothes made of natural fibers.
  • Keep skin cool with fans, air conditioning, or cool showers.
  • Exercise during the coolest time of day or indoors in air-conditioning.

Eczema

Eczema cannot be prevented but avoiding triggers can reduce flare-ups. Some triggers can't be completely avoided like dry weather and pollen. Other triggers such as food, cosmetics, and fragrances can be avoided.

Summary

Heat rash and eczema are two types of skin conditions that cause a rash with bumps. Heat rash can also cause a prickling sensation that can be painful. It is caused by sweat trapped under the skin. Eczema causes dry, scaly skin and may be due to genetics, environmental changes, or allergies. It's important to get the right diagnosis as each condition has a different treatment plan.

A Word From Verywell

Heat rash and eczema are similar yet very different rashes. One of the best ways to determine your type of rash is to think about your recent activities. Heat rash is caused by sweat, while eczema is a chronic (long-term) condition triggered by allergens like foods, lotions, or even stress. A healthcare provider can diagnose the rash and prescribe the right treatment.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Johns Hopkins Medicine. Eczema.

  2. MedlinePlus. Heat rash.

  3. American Academy of Dermatology Association. 12 summer skin problems you can prevent.

By Patty Weasler, RN, BSN
Patty is a registered nurse with over a decade of experience in pediatric critical care. Her passion is writing health and wellness content that anyone can understand and use.