Heat Rash or Eczema? How to Tell Why Your Armpits Are Red

Red, itchy armpits in the summer can be more than just annoying. They can be confusing too. Is it heat rash? Is it eczema? Or something else? If your underarms get irritated in warm weather, you’re not alone. Many people deal with this. The tricky part is figuring out what’s really going on with your skin so you can treat it the right way.

Red Armpits: What’s Causing It?

Before you can fix the problem, you need to know the cause. There are a few common reasons for red armpits. Some are linked to heat. Others are related to sensitive skin or allergies. Here are the top culprits:

• Heat rash under arms: Caused by sweat and blocked pores in hot, humid weather
• Eczema in armpits: Also called atopic dermatitis, a chronic skin condition that flares up with triggers
• Contact dermatitis: A reaction to deodorant, detergent, or fabric that touches your skin
• Fungal or bacterial infections: Warm, moist areas like armpits are perfect places for growth

Each of these has a different cause and needs a different treatment. That’s why it’s so important to know what you’re dealing with.

Heat Rash vs Eczema in Armpits: The Key Differences

Let’s break down the main difference between heat rash and eczema. These are two of the most common reasons for irritated skin under arms in the summer.

What Is Heat Rash?

Heat rash, also called prickly heat, happens when your sweat glands get blocked. Sweat builds up under your skin and causes tiny red bumps, itching, or a prickling feeling. It’s most common in hot, humid weather or after workouts.

Signs of heat rash under arms include:

• Red or pink bumps, sometimes with clear fluid inside
• Itchy or prickly feeling, especially when you sweat
• Appears suddenly in hot weather
• Goes away in a few days with cooling and drying

What Is Eczema?

Eczema is a chronic skin condition. It causes inflammation, itching, and dryness. You can get eczema in armpits if your skin is sensitive or reacts to certain triggers like heat, sweat, or ingredients in deodorant.

Signs of eczema in the underarms include:

• Dry, scaly, or thickened skin
• Intense itching, often worse at night
• Redness that lasts longer than a few days
• Recurring flare-ups

Understanding how to tell heat rash from eczema comes down to timing, texture, and triggers. Heat rash shows up fast in hot, sweaty conditions. Eczema tends to linger and may come back again and again.

Other Red Armpits Causes to Consider

Still not sure what’s going on? Here are more possible causes of itchy red armpits in summer:

• Contact dermatitis: Caused by a reaction to deodorant, soap, or laundry detergent
• Shaving irritation: Small red bumps or razor burn after shaving
• Fungal infections: Like candida, which thrives in moist, dark places
• Bacterial infections: Such as folliculitis, which causes red, inflamed hair follicles

If your rash includes pain, pus, or doesn’t improve after a few days, it’s best to check in with your doctor or dermatologist.

How to Soothe an Underarm Rash

No matter the cause, irritated skin under arms needs gentle care. The right underarm rash treatment depends on what’s causing it. But these tips can help calm most types of inflammation:

For Heat Rash

• Keep cool and dry. Use a fan or wear loose, breathable clothing.
• Skip heavy lotions or deodorants until it clears.
• Apply a cool compress to reduce itching.
• Use gentle powders like cornstarch to absorb sweat.

For Eczema

• Use a fragrance-free moisturizer daily.
• Switch to a deodorant made for sensitive skin.
• Try an over-the-counter anti-itch cream with hydrocortisone.
• Identify and avoid your personal triggers, like heat or certain fabrics.

If your eczema is severe or doesn’t improve, a doctor may prescribe stronger creams or other treatments.

For Other Causes

• If it’s a fungal rash, you may need an antifungal cream.
• For contact reactions, stop using the suspected product right away.
• Keep the area clean and dry. Avoid tight clothing that rubs.

Why Summer Makes It Worse

Many people notice their armpit rash in summer gets worse. That’s because sweat, heat, friction, and humidity all combine to irritate the skin. If you’re prone to eczema or heat rash, summer can be extra tough.

To protect your skin in hot weather, try these tips:

• Choose breathable fabrics like cotton or bamboo.
• Shower after sweating to prevent clogged pores or infections.
• Use gentle, non-irritating deodorants like those from MAGS Skin.
• Stay hydrated. Dry skin is more likely to react.

When to See a Doctor

If your rash doesn’t go away in a few days, gets worse, or comes with other symptoms like fever or pain, check with a medical professional. You may need prescription treatment or testing for allergies or infections.

Quick Takeaways: Heat Rash vs Eczema Armpits

• Heat rash is short-term. It appears quickly in hot weather and clears up when you cool down.
• Eczema is a long-term skin condition. It comes back and needs regular care.
• Both can cause itchy red armpits, but the texture and timing are different.
• Summer heat and sweat can trigger both, especially in sensitive skin.
• Gentle care and the right products can prevent and treat most underarm rashes.

Support Your Skin With MAGS

If your armpits are red, itchy, or irritated, your deodorant might be part of the problem. Many formulas use harsh ingredients like baking soda or alcohol. At MAGS Skin, we do things differently. Our deodorants use magnesium hydroxide, a gentle compound that fights odor without hurting your skin. It balances pH, reduces irritation, and keeps you fresh without the burn.

Your underarms deserve to feel as good as the rest of your skin. Whether you’re dealing with heat rash, eczema, or another form of inflammation, treating your skin gently is key. Listen to your body, watch for patterns, and don’t be afraid to switch up your routine. Your armpits will thank you.