That sore, red patch under your bust that flares in warm weather has a name, intertrigo, and it is far more common than most women realise. The good news: because it is driven by heat, moisture and friction, the right bra can do a lot to prevent it.
Quick answer: Intertrigo is an inflammatory rash that develops where skin rubs against skin, including under the breast fold. It is caused by the combination of warmth, trapped moisture and friction, which breaks down the skin barrier and can allow yeast or bacteria to take hold. The under-bust area is especially vulnerable because it is warm, enclosed and in constant motion. Prevention centres on keeping the fold cool, dry and low-friction, which is largely a fabric and fit problem.
Definition
According to DermNet, intertrigo is “a rash in the flexures”, the body's skin folds, such as under the breasts, in the groin, under the arms and under the abdomen. Cleveland Clinic describes it as inflammation of these folds, which can become secondarily infected. It typically looks red or raw, and may itch, burn, sting, weep, crack or develop an odour.
“Warmth, moisture, friction, and skin folds together create a perfect environment for irritation.” (adapted from Healthline)
Causes: why the under-breast fold is a hotspot
The inframammary fold checks every box for intertrigo:
- Heat is trapped between the breast and the chest wall.
- Moisture from perspiration cannot evaporate easily in an enclosed fold.
- Friction from movement and from a rubbing band or seam abrades the skin.
- Skin-on-skin contact keeps the area occluded all day.
Risk rises with heat and humidity, a larger bust, increased sweating (including during menopause), diabetes, and anything that keeps the fold damp. Once the barrier is disrupted, Candida yeast or bacteria can move in and worsen the rash. It is worth noting that inverse (flexural) psoriasis can look similar in the same location, another reason persistent rashes deserve a professional eye.
Intertrigo and its look-alikes
Several conditions share the under-breast fold, and telling them apart guides treatment:
- Candidal (yeast) intertrigo: when Candida colonises the inflamed fold, you may see satellite spots and a more defined, sometimes peeling, border.
- Inverse psoriasis: smooth, shiny, well-demarcated redness without the thick scale of typical psoriasis; it affects an estimated 21 to 30% of people with psoriasis.
- Contact dermatitis: irritation from a bra's dyes, finishes or metal hardware (see our guides to nickel allergy and contact dermatitis from clothing).
- Heat rash and simple chafing: short-lived irritation from a hot, sweaty, rubbing fold.
Because the management overlaps but is not identical (an antifungal helps yeast; a steroid helps psoriasis; avoidance helps contact dermatitis), a rash that keeps returning is worth showing to a clinician.
Prevention via fabric choice
Because intertrigo is driven by heat, moisture and friction, the right fabric and fit are genuinely preventive:
- Breathable natural fibres (cotton, bamboo, silk-lined) let heat and vapour escape instead of trapping them.
- Moisture-wicking linings move sweat away from the fold so the skin stays drier.
- Smooth, low-friction surfaces and flat or covered seams reduce mechanical rubbing.
- A correct band fit supports the bust so skin-on-skin contact is reduced, without digging in.
- Dry thoroughly after washing or sweating; DermNet suggests a cool hairdryer for the under-bust area, and a barrier powder can help.
How JulieMay helps reduce under-bust irritation
JulieMay bras are built around exactly these principles. A breathable organic-cotton body with a moisture-wicking pure-silk lining helps keep the fold cool and dry, while soft construction and considered seam placement reduce friction. For very reactive or fuller busts, our soft bralette styles and supportive wireless bras spread contact gently. Everything is allergy-friendly and free from the harsh finishes that can sting already-irritated skin.
When to seek medical advice
See a GP, pharmacist or dermatologist if the rash does not improve within a week or two of keeping the area cool and dry; becomes increasingly painful, weepy, crusted, smelly or spreads (possible infection); is accompanied by fever or feeling generally unwell; or recurs frequently, or you have diabetes or a weakened immune system.
Frequently asked questions
Is intertrigo an infection?
Not always. It begins as inflammation from heat, moisture and friction, but can become secondarily infected with yeast or bacteria, which changes the treatment.
Can the right bra really prevent intertrigo?
It can substantially reduce the risk. Breathability, a dry microclimate, low friction and good support all directly address the causes.
Key takeaways
- Intertrigo is a skin-fold rash driven by warmth, moisture and friction.
- The under-breast fold is a classic site; secondary yeast or bacterial infection can follow.
- Breathable, moisture-wicking, low-friction lingerie with a good band fit is genuinely preventive.
- Seek help for infection signs, persistent rashes, or if you have diabetes or immune issues.
Related reading
- How Friction and Sweat Cause Bra Rashes (And How to Prevent Them)
- Hidradenitis Suppurativa and Lingerie Comfort: What to Look For
- Contact Dermatitis From Clothing: Signs & Fabric Considerations
Sources: DermNet: Intertrigo; Cleveland Clinic: Intertrigo; Healthline: Intertrigo; National Psoriasis Foundation: Inverse psoriasis.
Educational content only; not a substitute for professional medical advice.
