Peanut App

What to Know if You Have a Rash Under Your Breast

last year6 min read
Last updated: Jan 23 2023

The skin around your breasts is pretty sensitive, so lots of women will get a rash under their breast at some point. A lot of things can cause irritation – from new products, to sweat, to infections.

Rash Under Breast

It’s always best to have a rash checked by a doctor so you can get the right treatment, but here’s an idea of what might be going on.

📝 In this article:

  • Why do you get rashes under your boobs?
  • Common reasons for an itchy rash under your breast
  • What does a breast cancer rash look like?
  • How to treat a rash under your breast

Why do you get rashes under your boobs?

It’s really easy to develop a rash under your breast, especially if you have larger breasts, or if you’re nursing.

Or if you have a small baby and you’re often holding or wearing them.

Your skin is more likely to get irritated if it gets wet and doesn’t have the chance to dry.

This can happen after a shower, swimming, sweating, or because of leaking breastmilk.

If the air can’t get to your skin – or if there’s rubbing and chafing because of the moisture – your skin gets weaker, and anything from sweat rash to a bacterial or fungal infection can take hold.

Common reasons for an itchy rash under your breast

Sweat rash

Also known as prickly heat, this underboob rash is a common complaint in the summer and from baby-wearing mamas who don’t get a lot of personal space.

It looks like small, raised, red spots which might blister or get itchy as they heal.

The best way to avoid this is to wash your skin after you’ve been sweaty and wear loose-fitting clothes made from natural fibers like cotton, linen, or silk – this goes for your underwear too.

Allergic reaction

Changed your laundry detergent recently? Or do you have a new strapless or stick-on bra? What about a different moisturizer or even nipple butter?

If you’re allergic to a new product, it’s not unusual for the rash to show up under your boob because your bra sits so close to your skin.

Depending on how severe your reaction is, your skin might be red and blotchy, or you might get raised hives.

Antihistamines can help with itching, but you should also watch for the symptoms of a more severe allergic reaction.


Speaking of reactions, it is possible to develop eczema under your breasts.

It’s more common to get eczema on your hands, face, or where your skin rubs together (think your elbows and the backs of your knees), but the skin under your boobs can also be affected.

Eczema is usually very dry and it can make your skin can crack.

It tends to flare up and then calm down depending on things like your diet, the environment, or your stress levels.


Mastitis is a bacterial infection that’s more common for nursing mamas.

It happens when one of your milk ducts gets blocked.

It’s pretty easy to clear up with antibiotics, but you’ll probably feel rough for a day or two before they start to work.

You’re unlikely to get a spotty rash with mastitis, but your skin can become very red and hot.

You’ll probably also feel like part of your breast is hard and badly bruised, and you may get a high fever, chills, and fatigue.


Intertrigo is the most common fungal infection that affects the skin under the breasts.

It’s actually a form of candida (or yeast) infection.

What does an intertrigo rash look like?

If this is the problem, your skin will probably be raw, inflamed, and very itchy.

The rash can also crack or weep, and the discharge can smell bad.

It’s also pretty common for the same fungus to cause a thrush infection on your nipple in the early days of nursing, when your skin might be particularly tender and cracked.

If you think you have intertrigo, see your doctor so that you can get the proper cream or antifungal tablet to clear it up.

They’ll also rule out other conditions like scabies or psoriasis that would need a different treatment.


Shingles might not be the first thing you think of if you’re young and healthy, but if you had chickenpox as a child and you get rundown (like after another illness, or after you’ve had a baby) it can happen.

And it’s not uncommon for the blistery rash to appear under one of your breasts.

Shingles rash usually appears on one side of the body, and you’ll probably also have a fever, chills, and nerve pain in your back and shoulders.

If you think your rash might be shingles, see your doctor straight away to collect some antivirals and zinc cream for the rash.

What does a breast cancer rash look like?

It’s not usually helpful to assume the worst, but since breast cancer is the most commonly diagnosed cancer in the US, everyone should know the signs and symptoms.

It can affect the skin and a rash at the beginning of breast cancer is not uncommon.

Here’s what to look for:

  • Your skin might be dimpled – lots of people compare it to orange or lemon peel.
  • Your breast might look and feel inflamed – there’s a chance your skin might be red and warm to the touch.
  • Your skin might become flaky, especially around your nipple.

If you notice any of these changes, it’s worth making an appointment to have your breasts checked, even if you can’t feel a lump when you do a self-exam.

How to treat a rash under your breast

If you have painful or annoyingly itchy skin, you’re probably wondering what you can put on a rash under your breast.

Unless it’s a problem you’ve had before, like a seasonal sweat rash or an eczema flare-up, it’s best to check with your doctor before you treat a rash by yourself.

It’s tempting to put something like a thick moisturizer on your skin when it’s irritated, but that won’t usually treat the underlying problem.

It might even stop the air from getting to your skin and make things worse.

So if the rash isn’t clearing up on its own, or if you have any other symptoms like pain or a fever, make an appointment.

And in the meantime, the best thing you can do is wash your skin regularly with plain, warm water, and pat it dry rather than rubbing it – no matter how tempting it is to scratch.

💡 More from The 411:
What to Do About a Postpartum Rash
7 Breastfeeding Positions to Try
Why Are My Breasts Getting Bigger After Menopause?
9 Soothing Pregnant Skincare Products
Your Quick Guide to Pregnancy Safe Skin Care
The 411 on Breast Massage
Breasts Leaking During Pregnancy? What to Know
Breast Reduction Surgery Cost: All You Need To Know

Popular on the blog
Trending in our community