SWEAT RASH: CAUSES, SYMPTOMS, AND TREATMENTS

If you’re hitting the gym more regularly or sweating more often, you may have experienced a sweat rash, also known as heat rash or prickly heat. This common condition can cause some discomfort, so let’s explore the causes and symptoms, and  get practical ways to prevent it.

WHAT IS A SWEAT RASH?

A sweat rash is a specific type of skin rash that develops when you sweat a lot or are in a hot place, and your sweat ducts get blocked. When these sweat ducts are blocked, it can lead to a rash—small sweat-filled blisters under your skin.¹

A sweat rash can affect anyone. But people living in warm and humid climates and athletes are at higher risk. In fact, it affects up to 30% of adults living in hot and humid conditions. ²

HEAT RASH VS. SWEAT RASH

While the terms are often used interchangeably, there is a difference between heat rash and sweat rash. Sweat rash specifically refers to the blockage of sweat ducts, leading to a rash. Heat rash, on the other hand, is a broader term that includes various types of rashes caused by heat, including sweat rash.

WHAT CAUSES A SWEAT RASH?

There are many causes of a sweat rash, ranging from hot and humid conditions to fabric choices for your clothing. Let's explore five of the most common ones:

WHAT DOES SWEAT RASH LOOK LIKE

If you’re wondering if you have a sweat rash, look out for the following signs:2

• Red bumps or tiny blisters on the skin. Small red bumps or tiny blisters might pop up, and they can be itchy.
• Prickling sensation. Your skin might feel a bit prickly or tingly, especially where you sweat or where the rash is.
• Itching and discomfort. You might feel itchy, and the affected area can be uncomfortable.
• Swelling. The skin could turn red and a bit swollen, especially in the area of the rash.
• Rash clusters or patches. The rash might show up in groups or patches, along the paths where you sweat.

UNDERSTAND THE TYPES OF SWEAT AND HEAT RASHES YOU GET

Not all sweat rashes are alike and you may have heard some of the medical terms. There are three main types you might be asking about:³

1. What is miliaria crystallina?

Miliaria crystallina is a type of heat rash, but it is not typically considered a true sweat rash since it results from a superficial blockage of sweat glands rather than deeper inflammation. It is the mildest form of heat rash, causing small, clear, fluid-filled blisters on the skin’s surface. These blisters are fragile and can easily break.

2. What is miliaria rubra or prickly heat?

Miliaria rubra, or prickly heat, is a type of heat rash that occurs when deeper sweat ducts become blocked, causing red, inflamed bumps and a prickling sensation. It is more irritating than miliaria crystallina, as sweat leaks into surrounding skin tissue. Common in hot, humid conditions, it can worsen with excessive sweating or friction. In some cases, the bumps may fill with pus, known as miliaria pustulosa.

3. What is miliaria profunda

Miliaria profunda is a heat rash that occurs when sweat leaks into deeper skin layers due to chronic sweat duct blockage. It causes firm, flesh-colored bumps that may be painful or itchy and is common in those frequently exposed to hot, humid conditions.

HOW TO TREAT  SWEAT RASH

While sweat rashes usually clear up on their own, there are some things that you can try to help ease the sweat rashes.

• Keep the affected area cool and dry by taking cool showers and patting the skin dry.
• Wear loose, breathable clothing to reduce friction and irritation.
• Apply a cold compress to soothe itching and inflammation.
• Avoid heavy lotions, creams, or petroleum-based products that can further block sweat

If your sweat rash persists for more than a few weeks, worsens, becomes painful, or shows signs of infection (such as pus, swelling, or fever), consult a healthcare professional for treatment.

HOW TO PREVENT SWEAT RASH BEFORE IT STARTS

Preventing sweat rash is all about keeping your skin cool and dry. Here are some pro tips to help you avoid sweat rash:

• Wear loose, breathable clothing.
• Stay in cool, air-conditioned environments when possible.
• Take frequent cool showers.
• Use antiperspirants like Degree’s Whole-Body Deodorant to manage sweat.

FAQs

Is sweat rash contagious?

Sweat rash is not contagious. It can’t spread from person to person.

Can sweat rash spread?

Sweat rash itself doesn’t spread, but if you continue to sweat and your sweat ducts remain blocked, the rash can appear in new areas.

How long does sweat rash last?

A mild sweat rash usually clears up in a day to three days. Severe cases may take a couple of weeks and might require medical attention.

Is sweat rash fungal or bacterial?

Sweat rash is neither fungal nor bacterial. It’s caused by blocked sweat ducts.

What’s the best way to prevent sweat rash in summer?

Stay cool, wear breathable clothing, and use a whole-body deodorant for head-to-toe sweat and odor control.

 

Sweat rashes can make things uncomfortable fast, but they don’t have to be your reality. With the right know-how and a few simple tricks, you can keep your skin calm, cool, and rash-free. Loose, breathable clothing? Essential. Staying chill? Non-negotiable. And don’t forget to back yourself up with an effective Degree antiperspirant to keep sweat in check.

References:

1. Cleveland Clinic. "Heat Rash/Prickly Heat." Updated 2022.

2. National Library of Medicine. “Miliaria.” Updated 2024.

3. American Osteopathic College of Dermatology. “Miliaria.” Accessed March 2025.