Why Every Gynecologist Says the Same Thing About Your Underwear

And why most brands still aren't listening.

There's one piece of advice that comes up in virtually every gynecologist visit, printed on every women's health pamphlet, and echoed across every credible medical resource: wear cotton underwear.

It's not a trend. It's not a marketing gimmick cooked up by a fabric lobby. It's a recommendation backed by decades of clinical observation and, increasingly, peer-reviewed research. So why is it so hard to find underwear that actually follows it?

The Science: What Cotton Does That Synthetics Don't

The vulvar skin is among the most sensitive and absorptive tissue on the human body. Unlike the skin on your arms or legs, it's thinner, has more blood vessels, and lacks the same protective barrier. What touches it matters — a lot.

Cotton is naturally breathable and moisture-wicking in a way synthetics simply aren't. It allows air circulation and absorbs moisture away from the skin, keeping the vulvar area drier. This matters because warm, moist environments are exactly where opportunistic organisms like Candida thrive.

A 2022 study published in Medical Mycology examined 470 women and found that those who wore non-cotton underwear were at significantly higher risk of developing vulvovaginal candidiasis (VVC) — the clinical term for yeast infections. The study identified non-cotton underwear as a standalone risk factor alongside oral contraceptive use and history of recurrent infections (Fernandes et al., 2022, Med Mycol, 60(5), PMID: 35482711).

That's not a suggestion. That's a statistically significant finding from a controlled study.

It's Not Just About Yeast Infections

The issues with synthetic fabrics go beyond candidiasis:

• Contact dermatitis: A 2019 case report in Contact Dermatitis documented textile-induced vulvar and perianal dermatitis — irritation caused directly by synthetic underwear fabrics and their chemical finishes (Preston et al., 2019, Contact Dermatitis, 81(1):66-67, PMID: 30663079). Synthetic garment production introduces compounds that are known skin irritants, particularly in sensitive areas.
• Bacterial vaginosis: The same moisture-trapping properties that encourage yeast also create conditions favorable for bacterial imbalance. The Mayo Clinic lists wearing breathable, cotton underwear as a preventive measure for vaginal infections broadly — not just yeast.
• Urinary tract infections: While the direct link between underwear fabric and UTIs is less established, medical guidance consistently recommends cotton underwear as part of a broader hygiene strategy for women prone to recurrent UTIs. The logic is the same: reduce moisture, reduce bacterial proliferation.

The "Cotton Crotch Panel" Trick

Here's where the underwear industry gets sneaky. Many brands advertise a "cotton crotch panel" or "cotton gusset" — a small strip of cotton sewn into an otherwise synthetic garment. It sounds reasonable until you think about it for more than five seconds.

The vulvar area doesn't exist in a vacuum. The surrounding fabric — the waistband, the sides, the back — still traps heat and restricts airflow. A cotton strip in the middle of a nylon thong is like putting a screen door on one window of a sealed greenhouse.

If breathability and skin health are the goals, the whole garment needs to be cotton. Not just the part that technically touches you the most.

Why "100% Cotton" Is So Rare in Underwear

Cotton is harder to work with. It doesn't have the natural stretch of nylon or spandex. It wrinkles. It's more expensive to source in high quality. And frankly, it has a reputation problem — most people picture the frumpy, shapeless cotton underwear their grandmother wore.

So brands default to synthetics. They're cheaper, they stretch easily, and they photograph well. The trade-off is your health, but that's not something that shows up in a product photo.

The challenge has always been making 100% cotton underwear that actually looks and feels modern — that has the sleek fit of synthetic without the health compromises. It's a harder engineering problem, which is exactly why most brands skip it.

What to Look For

If you're re-evaluating your underwear drawer (and after reading this, you probably should), here's what actually matters:

1. 100% cotton fabric — not "cotton-blend," not "cotton-lined," not "cotton-feel." The real thing.
2. Transparency about sourcing — look for brands that tell you where their cotton comes from and how it's processed.
3. Breathable construction — the design should allow airflow, not just the fiber content.
4. Fit that works with your body — underwear you constantly adjust is underwear that's creating friction. Good fit isn't vanity; it's function.

The Bottom Line

Every gynecologist recommends cotton. The research supports cotton. Your body knows the difference, even when you're not consciously thinking about it. The underwear industry just hasn't caught up yet — mostly because it's easier and cheaper not to.

Your underwear is the garment closest to the most sensitive part of your body. It shouldn't be an afterthought, and it definitely shouldn't be made from the same material as your grocery bags.

Sources:

• Fernandes, Â. et al. (2022). "Vulvovaginal candidiasis and asymptomatic vaginal colonization in Portugal: Epidemiology, risk factors and antifungal pattern." Medical Mycology, 60(5), myac029. DOI: 10.1093/mmy/myac029. PMID: 35482711.
• Preston, A. et al. (2019). "Textile-induced vulvar and perianal dermatitis." Contact Dermatitis, 81(1), 66-67. DOI: 10.1111/cod.13227. PMID: 30663079.
• Mayo Clinic. "Yeast infection (vaginal) — Symptoms and causes." mayoclinic.org.
• American College of Obstetricians and Gynecologists (ACOG). Vulvar care guidelines.