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Why Is My Underwear Making Me Itch?

May 26, 2014 Admin Cottonique

If your underwear is making you itch, the useful question is not "is it the fabric?" but "which part of it?" — because a pair of cotton knickers usually contains four or five different materials.

The five suspects

1. The elastic

The most common culprit, and the one people check last. Waistband and leg elastic is rubber — either natural latex, or synthetic rubber made with accelerators such as thiurams and carbamates. Both are well-documented contact allergens, and the band sits under tension in one fixed position all day.

The tell: irritation follows a line — across the waist, or around the leg opening — rather than being general. If that is what you are seeing, changing the fabric will not help. You need a drawstring waist or a genuinely elastic-free style.

2. The dye

Disperse dyes, used to colour synthetic fibres, are among the more common textile contact allergens.

The tell: it happens with coloured pairs and not with white or natural ones. Undyed removes the variable entirely.

3. The finish

Wrinkle-resistant, softening and anti-odour treatments are applied to fabric after it is made. Formaldehyde-based resins are used for wrinkle resistance; anti-odour finishes are often silver- or zinc-based.

The tell: a new pair irritates and the same pair is better after several washes, as the finish partly washes out.

4. The fibre

Polyester and nylon do not absorb moisture — they hold it against the skin. That is less an allergy than an environment: warm, damp and enclosed.

The tell: worse in heat, after exercise, or by the end of a long day.

5. What you wash them in

Detergent and fabric conditioner residue stays in the fabric and sits against the skin for as long as you wear it. Fragrance is a frequent trigger.

The tell: everything irritates, including garments you have worn happily before. Switch to a fragrance-free detergent, skip conditioner, and run an extra rinse.

"But I already wear cotton"

This is the most common thing we hear, and it is usually explained by the list above. Underwear sold as cotton is normally cotton in the body only — the band is rubber, the stretch is elastane, the seams are sewn with polyester thread, and the whole thing may carry a finish. If you switched to cotton and still itch, the cotton is probably the one part that is not the problem.

What about the smell?

Odour and itching often turn up together, and they share a cause: moisture that has nowhere to go. Synthetic fabric keeps moisture at the surface, and the bacteria responsible for odour do well in exactly those conditions — which is why polyester develops a persistent smell that washing struggles to shift and cotton generally does not.

A sharp ammonia-like smell is worth mentioning to a doctor rather than treating as a laundry problem. Persistent odour or discharge is a medical question, not a fabric one.

How to work out which it is

Change one thing at a time. Start with the detergent, because it is free. Then try an undyed pair. Then try a style with no elastic against the skin. Changing everything at once tells you nothing about what to avoid next time.

What we make

Our organic cotton underwear is 100% GOTS-certified cotton, made without latex, spandex or elastane. The Nothing But Cotton range removes the rest of the variables too — no elastic at all, no dye, no synthetic thread. If you react to several things and cannot tell which, that is the sensible place to start, because there is very little left in it to react to.