Armpit Rash After Running? It Might Be Chafing or Eczema
Ever finish a run only to find your armpits red, itchy, or even stinging? That painful underarm rash after running isn’t just annoying. It can mess with your workouts and make you dread putting on a sports bra or tank top. Whether it’s chafing, eczema, or a reaction to sweat, the good news is: there are real solutions. You don’t have to suffer through the sting to stay active.
Why You Get Armpit Rashes After Running
When your armpits get irritated after exercise, there are usually two main culprits: friction and sweat. Let’s break them down.
1. Chafing
Chafing happens when skin rubs against skin or clothing. Add some moisture from sweat, and you’ve got the perfect storm for a friction rash under your arms. This is especially common for runners and athletes who wear tight gear or move their arms a lot.
Signs of underarm chafing include:
- Red, raw patches
- Stinging or burning feeling
- Peeling or cracked skin
2. Eczema
Eczema under armpits is a different issue. It’s usually caused by sensitive skin reacting to heat, sweat, or even harsh deodorants. If your rash is itchy, dry, or flaky, eczema might be to blame.
Signs of eczema under armpits:
- Dry, scaly patches
- Itching that won’t quit
- Redness or dark discoloration
In some cases, you can have both chafing and eczema. The friction can trigger a flare-up if your skin is already sensitive.
What to Do If You Have an Armpit Rash From Running
First, don’t panic. Armpit rash after running is common, especially in warm weather or during long workouts. Here’s how to handle it.
Step 1: Cleanse Gently
After your run, wash your underarms with a mild, fragrance-free cleanser. Avoid scrubbing. You want to remove sweat and bacteria without irritating your skin more.
Step 2: Soothe the Skin
If it’s chafing, apply a healing ointment like petroleum jelly or a balm made for athletes. For eczema, use a moisturizer with ingredients like ceramides or colloidal oatmeal.
Step 3: Skip the Harsh Deodorant
Many deodorants contain alcohol or baking soda, which can make things worse. The best deodorant for armpit rash will be fragrance-free, baking soda-free, and made with gentle ingredients like magnesium hydroxide. MAGS Skin’s formula was made for this exact issue.
Step 4: Let Your Skin Breathe
Loose, breathable clothing helps your skin recover. If you can, skip the tight tops until the rash clears up. Cotton or moisture-wicking fabrics are your friend.
How to Prevent Chafing and Eczema Before They Start
If you’re active, prevention is key. These athletic skin care tips can help you stay rash-free no matter how hard you train.
Use a Barrier Before You Sweat
Before your workout, apply a layer of anti-chafe balm or petroleum jelly to your underarms. This reduces friction and keeps sweat from irritating your skin. It’s a simple but powerful chafing prevention for athletes.
Choose the Right Deodorant
Look for deodorants made for sensitive skin. Avoid aluminum, alcohol, and artificial fragrances. Magnesium-based formulas are a great choice because they fight odor without irritating your skin.
Wear the Right Gear
Clothing matters more than you think. Choose:
- Moisture-wicking fabrics
- Seamless or flat-seam tops
- Properly fitting sports bras and tanks
If your clothing is too tight or too loose, it can rub the wrong way and cause problems.
Shower and Moisturize After Every Workout
Leaving sweat on your skin too long can lead to irritation, clogged pores, and even fungal infections. After you cool down, hop in the shower and moisturize right after. This helps lock in hydration and protect your skin barrier.
When to See a Dermatologist
If your rash doesn’t go away after a few days of home care, or if it gets worse, it’s time to see a doctor. Signs you should call a pro include:
- Blistering or open sores
- Signs of infection (pus, swelling, fever)
- Rash that spreads beyond your underarms
Some rashes need prescription creams or allergy testing. Don’t try to tough it out if your skin is in pain. Sensitive skin isn’t weak. It just reacts faster.
Best Runner's Rash Remedies That Actually Work
Want a go-to plan for fast relief? Here’s a simple runner’s rash remedy routine:
- Before your run: Apply an anti-chafe balm or soothing deodorant like MAGS Skin to reduce friction.
- During your run: Wear breathable gear. Avoid cotton, which traps moisture.
- After your run: Gently cleanse with warm water and a mild cleanser. Pat dry. Moisturize with a fragrance-free lotion.
Consistency matters. The more you care for your skin before and after workouts, the less likely you are to deal with rashes.
Quick Takeaways: Keep Your Armpits Rash-Free
Feel like your armpits hate cardio? You’re not alone. Here’s what to remember:
- Friction and sweat are the top causes of armpit rash after running
- Chafing feels raw and stings, while eczema itches and flakes
- Use gentle, fragrance-free products to clean and moisturize
- Apply a barrier before working out to prevent rubbing
- Choose skin-friendly deodorants like MAGS Skin to reduce irritation
Final Thoughts: Sweat Doesn’t Have to Mean Suffering
Running and workouts should make you feel strong, not sore under the arms. With the right care, you can avoid that itchy, painful rash and keep moving with confidence. Whether it’s chafing or eczema, knowing your skin’s needs is the first step. Try swapping your deodorant, switching your gear, and setting up a simple pre-and post-run routine. Your underarms will thank you.
Need an underarm upgrade? MAGS Skin is made for athletes and sensitive skin alike. It’s the best deodorant for armpit rash because it fights odor without irritation. No baking soda, no aluminum, no sting. Just smooth, calm skin mile after mile.