Why Your Armpits Rash After Swimming (and What Helps)

Swimming is supposed to leave you feeling refreshed, not itchy. But if your armpits break out in a rash after a dip in the pool or ocean, you're not alone. Whether it’s red bumps, stinging patches, or dry, irritated skin, many people deal with underarm irritation from swimming. Let’s break down why your armpits react this way and what you can do to stop it.

Why Do You Get an Armpit Rash After Swimming?

There are a few common triggers behind that uncomfortable underarm rash. Most of them come down to a mix of chemicals, friction, and how sensitive your skin is. Here are the main culprits:

1. Chlorine and Pool Chemicals

Chlorine keeps swimming pools clean by killing bacteria. But it can also be harsh on your skin. If you have sensitive skin, chlorine can strip away your natural oils and throw your skin’s pH off balance. This can lead to:

• Red itchy armpits after swimming
• Dry, flaky patches
• Chlorine rash underarms that burn or sting

Some people even develop an armpit allergy to chlorine. It’s not a true allergy, but your skin can become sensitized over time. This makes it more likely to react with each exposure.

2. Saltwater and Ocean Exposure

Saltwater might sound gentler than chlorine, but it has its own challenges. While salt can help cleanse the skin, it can also dry it out. Combine that with sand, sun, and sweat, and you’ve got a recipe for irritation. The result? A saltwater rash on your armpits that feels raw and uncomfortable.

3. Friction and Moisture

When your skin is wet and soft from swimming, it’s more prone to chafing. The armpit area is especially sensitive because it’s warm, tight, and always moving. Add tight swimsuits or sweaty towels, and you might see:

• Underarm bumps from swimming
• Red, irritated skin that sticks around for days
• Stinging or burning when you apply deodorant afterward

Why Armpits Are So Sensitive

Your underarms are one of the most delicate spots on your body. The skin is thinner and more absorbent. It also has more sweat glands, hair follicles, and friction than other areas. That makes it more likely to react to:

• Harsh pool chemicals
• Sand, salt, and sunscreen
• Heat, sweat, or rubbing from swimsuits

If you already deal with eczema, dermatitis, or other skin conditions, your armpits may react even faster. This is what we mean by a sensitive skin rash from swimming.

How to Treat an Armpit Rash After Swimming

If your underarms are red, itchy, or breaking out after a swim, don’t worry. There are simple ways to calm your skin and stop the irritation. Here’s how to treat a swimming pool rash quickly and gently.

1. Rinse Off Right After Swimming

Don’t wait to shower. Rinse off as soon as you leave the pool or ocean. Use cool or lukewarm water to wash away chlorine, salt, and sweat. Avoid hot water, which can make the rash worse.

2. Use a Gentle Cleanser

Skip the strong soaps. Use a mild, fragrance-free cleanser that won’t strip your skin. Look for one made for sensitive skin. This helps restore your skin’s natural balance without causing more irritation.

3. Pat Dry, Don’t Rub

Use a soft towel and gently pat your underarms dry. Rubbing can make the rash worse, especially if your skin is already inflamed.

4. Soothe with a Skin-Calming Product

Try a magnesium-based deodorant or balm. Magnesium hydroxide is gentle and helps calm irritation while balancing your skin’s pH. It doesn’t block sweat. It just stops the stink and keeps your underarms healthy.

You can also use products with aloe vera or colloidal oatmeal to relieve itching and redness. Avoid anything with alcohol, scent, or baking soda, which can burn or sting.

5. Skip Deodorant for a Day or Two

If your underarms are raw or bumpy, give them a break. Let the skin heal before applying deodorant again. When you do start back, choose one made for sensitive skin that’s free from baking soda and synthetic fragrance.

6. Wear Loose, Breathable Clothing

After swimming, avoid tight or synthetic fabrics that trap heat and moisture. Stick with natural fibers like cotton. They help your skin breathe and reduce friction.

How to Prevent Armpit Rash Before It Starts

Prevention is key. If your skin reacts every time you swim, try these steps to protect your underarms before you hit the water.

1. Apply a Barrier Cream

Use a thin layer of petroleum jelly or a natural balm before swimming. This creates a barrier between your skin and the water to help reduce contact with chlorine or salt.

2. Shower Before Swimming

Rinsing your body before you get in the pool can help reduce how much chlorine your skin absorbs. Wet skin also soaks up fewer chemicals.

3. Choose the Right Swimwear

Pick swimsuits that fit well but aren’t too tight around the arms. Avoid anything with rough seams or elastic that rubs against your underarms.

4. Moisturize After Swimming

Keep your skin hydrated with a gentle, non-comedogenic lotion after every swim. Healthy, moisturized skin is less likely to react to irritants.

When to See a Doctor

If your rash doesn’t go away after a few days, or if it gets worse, it’s time to get it checked out. You might be dealing with a fungal infection, allergic reaction, or something else that needs treatment. Watch for signs like:

• Severe itching or burning
• Blisters or open sores
• Rash spreading beyond the armpits

Your doctor can recommend the best swimming pool rash treatment for your skin. This might include a prescription cream or allergy test if the issue keeps coming back.

Quick Takeaways

• Chlorine and saltwater can strip your skin, especially in sensitive spots like your underarms
• Friction and moisture make things worse, leading to bumps, redness, and itching
• Rinse off, pat dry, and soothe your skin right after you swim
• Use gentle, magnesium-based products to avoid further irritation
• Protect your skin with barrier creams and loose clothing to prevent future rashes

The Bottom Line

If you deal with an armpit rash after swimming, it’s not just you. Whether it’s a chlorine rash under your arms or a saltwater rash on your armpits, your skin is just reacting to stress. The good news? You can calm it down and stop it from coming back. Be kind to your underarms. Choose products that support your skin’s balance instead of fighting it. And if you’re looking for a deodorant that won’t make things worse, MAGS Skin has your back.