Why Do I Sweat Under My Breasts, and How Do I Treat the Rash?

By mid-afternoon the band of your bra is damp. By evening there’s a sting under there that gets worse in the shower. You’ve started wearing a cardigan in July.

Why the fold stays wet

Sweat glands are everywhere, including the breast area. Cleveland Clinic¹ says both kinds, eccrine and apocrine, are found throughout the body. The difference under the breasts is the lack of air. Sweat that would evaporate elsewhere sits in the fold.

The smell comes from the same chain as armpit odor. Apocrine glands release an oily fluid that’s usually odorless, and the characteristic odor develops when bacteria break it down. Our article on why you can still smell after a shower covers that chain in more detail.

When damp becomes a rash

Cleveland Clinic² calls the rash intertrigo: an inflammatory skin condition caused by skin-to-skin friction that heat and moisture make worse. It commonly appears beneath or between the breasts. It isn’t an infection by itself, though one can develop on top of it.

Risk factors on its list include obesity, diabetes, excessive sweating, incontinence, and hot, humid climates. A hospital leaflet from Gateshead Health NHS Foundation Trust³ says it’s most common in women who have large breasts or who are highly active.

The early signs are a reddish rash with small bumps and itching, stinging or burning. Without treatment it can progress to raw skin, cracks, bleeding and crusting. The Gateshead leaflet describes red or reddish-brown skin and weeping that often smells.

When it’s yeast

The same warm fold is a good home for yeast. The Gateshead leaflet says the warmth and moisture create an environment where bacteria, yeast and fungi grow, and names Candida albicans as a main culprit.

Cleveland Clinic⁴ describes a yeast infection under the breasts as a bright red rash that may be raised, swollen, tender or shiny, with itching or pain, burning or stinging. The skin around it can turn dry, flaky and cracked, and sometimes blisters that crust over and ooze.

Its risk list adds tight clothing, infrequent changes of bras and undergarments, not drying well after a bath, breastfeeding, breast pads, hot weather, and heavy sweating.

Treatment is an antifungal medicine applied to the skin, and sometimes a pill when a clinician decides it’s needed.

What keeps the fold dry

Most of what works is unglamorous.

Cleveland Clinic¹ recommends loose, breathable fabrics like cotton to wick away moisture, and says to avoid synthetics like nylon and acrylic. The American Academy of Dermatology (AAD)⁵ gives the same advice for heavy sweating: breathable fabrics like cotton. Cleveland Clinic also says to consider removing the padding from a sports bra, since padding can hold sweat.

After a workout, shower as soon as you can and wash the area with soap and water. If you can’t shower, change into clean clothes.

Then the fold itself. Cleveland Clinic¹ says a talc-free powder, a whole-body deodorant, or a skin barrier balm or cream can cut the friction before you put your bra on. For intertrigo, its guide says the main step is keeping the area dry, clean and cool, with zinc oxide barrier creams or drying powders as options.

The Gateshead leaflet has two tips that sound almost too easy. Dry the area with a cool hairdryer. Wear a bra that fits well and supports you, and change it daily. It also says a cotton top under the bra can help, and that losing weight can reduce the skin-on-skin friction.

Our take: the cool hairdryer sounds like a joke and costs nothing, so try it.

The play

Try this: dry first, then dress

After your shower, pat the fold dry, then use a hairdryer on its cool setting until the skin is completely dry.

Put on a barrier cream or talc-free powder before your bra.

Wear a clean, well-fitting bra with a thin cotton layer under it.

When to get checked

Cleveland Clinic² says to contact a provider if an intertrigo rash persists, gets worse suddenly, or shows signs of infection such as a foul odor or pus. It warns that untreated intertrigo can lead to cellulitis, a deep skin infection. For a suspected yeast infection, it says to see a provider if the rash lasts beyond two weeks despite treatment, since stronger treatment may be needed. The Gateshead leaflet says to see your pharmacist or GP if it persists.

Make an appointment if any of these fit:

• The rash hasn’t improved after two weeks of keeping the area dry
• The skin is cracked, raw, bleeding or crusting
• You notice pus or a strong foul smell
• The rash gets worse suddenly
• It keeps coming back. Cleveland Clinic² lists diabetes as a risk factor, so mention it.

That damp band at 3 p.m. isn’t a flaw in you. Dry the fold, dress it in cotton, and leave the cardigan for October.