How Do You Prevent Chafing in Hot Weather? A Dermatologist's Guide

In a recent interview with Katie Hannon and Colm Ó Mongáin on RTÉ Radio 1's Drivetime, Professor Caitriona Ryan, Consultant Dermatologist and Co-founder of the Institute of Dermatologists, was asked one of the least glamorous but most common summer skin complaints: chafing.

Chafing happens year-round but worsens in hot weather, when heat and sweat increase friction between skin surfaces. Prevention comes down to reducing friction directly — through fabric choice, fit, and a simple barrier product like Vaseline.

Chafing happens year-round but worsens in hot weather, when heat and sweat increase friction between skin surfaces. The most affected areas are the inner thighs, under the breasts, and the underarms. Prevention comes down to reducing friction directly — through fabric choice, fit, and a simple barrier product like Vaseline.

Why Does Chafing Get Worse in Summer?

Chafing is a friction injury, and friction increases with heat and sweat. Skin that rubs against itself or against clothing causes more irritation when it's damp than when it's dry, which is why symptoms that might be minor in cooler months become genuinely painful in a heatwave.

Where Does Chafing Happen Most?

Three areas come up repeatedly: the inner thighs, under the breasts (particularly for those with larger breasts, where the skin-on-skin contact area is greater), and the underarms. Anyone who runs or walks regularly for exercise will recognise this pattern, since repetitive movement multiplies the friction.

How Can You Prevent Chafing?

Professor Ryan's advice is practical rather than product-heavy:

• Apply Vaseline to friction-prone areas, such as the inner thighs, before activity. It creates a barrier that reduces direct skin-on-skin or skin-on-fabric friction.

• Wear a well-fitted, supportive sports bra. Reducing movement reduces friction at the source, which matters particularly for larger breasts.

• Check for seams in underwear and shorts. Wherever a seam sits directly against skin that's already prone to friction, irritation is more likely.

• Choose cotton or sweat-wicking fabric. Cotton absorbs sweat; technical sweat-wicking gymwear pulls moisture away from the skin, both of which reduce the dampness that makes friction worse.

• Consider seamless "anti-chafing" underwear. These are specifically designed without the stitching that typically causes irritation, and are now widely available.

Frequently Asked Questions

Where does chafing happen most often?

The inner thighs, under the breasts, and the underarms are the most commonly affected areas, particularly during exercise or in hot weather.

Does Vaseline actually help prevent chafing?

Yes. Applying it to friction-prone areas before activity creates a barrier that reduces skin-on-skin and skin-on-fabric friction.

Why does chafing get worse when it's hot?

Heat increases sweating, and damp skin experiences more friction and irritation than dry skin, which is why chafing tends to flare in summer weather or during exercise.

Are cotton fabrics better for preventing chafing?

Cotton absorbs sweat well, which helps. Technical sweat-wicking activewear is also effective, as it pulls moisture away from the skin rather than letting it sit.