• 5-pack of black Bamboo Lyocell men’s boxers offering soft, breathable comfort and support for male fertility health.
  • Back view of black bamboo Lyocell men’s underwear by Mr. Fertyl, designed for breathability, comfort, & fertility support.
  • Close-up of male model in black Mr. Fertyl fertility-safe boxers, made from breathable bamboo Lyocell for comfort and health
  • Rear view of male model wearing black Mr. Fertyl bamboo Lyocell boxers designed for breathability and fertility safety.
  • Male model posing in black Mr. Fertyl fertility-safe boxers, made from bamboo Lyocell for reproductive health and comfort.
  • Free Fertility Blueprint eBook for Men – 26 Pages of Tips, Supplements & Habits to Boost Reproductive Health
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The Fertility Boxer

The Fertility Boxer

✓ Built for Sperm Health
✓ Up to $30 Off When You Bundle
✓ Free Fertility Blueprint ($30 Value)
✓ 30-Day Guarantee + Free US Shipping on $120+
$190.00 USD
$200.00 USD $190.00 USD
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Save $10 on 5 Pack | Save $30 on 7 Pack

Product Description

Protect Sperm With Underwear. Not just another pair of boxers—this is a daily health decision. Made with Bamboo Lyocell, these boxers are engineered to support reproductive wellness and shield what matters most: future fertility.

Why Couples Choose Mr. Fertyl:

  • Fertility-First Design: Built to minimize heat retention and block endocrine-disrupting toxins from contacting the most sensitive areas.

  • Cloud Soft for Sensitive Skin: Breathable, OEKO-TEX® Class 1–certified fabric—safe enough for infants, trusted for fertility.

  • No Plastics, No Synthetics: Free from polyester, nylon, and any microplastic-based materials that leach chemicals through skin contact.

  • Covered Waistband Protection: Elastic waistband is fully enclosed our Bamboo Lyocell fiber to avoid direct skin exposure to harsh materials.

  • Certified Clean: OEKO-TEX® certified. No formaldehyde, PFAS, phthalates, microplastics, or other toxins.

  • Sustainable by Science: Produced in a closed-loop system using 99% recycled water and safe solvents. 1/3 the water usage of cotton.

  • Built to Last: Wash after wash, they hold their shape and stay soft. Pre-shrunk for lasting shape.

Designed to do one job—and do it better than anything else on the market: protect and support sperm health, every single day.

Concerned About Fit?

Each multi-pack includes the Fertility Fit Guarantee: one pair can be tried risk-free. If it doesn’t feel right, the rest can be returned or exchanged—no questions asked.

Materials & Care

Mr. Fertyl underwear are crafted with the utmost care, combining comfort, sustainability, and durability:

Materials:

95% Bamboo Lyocell: Naturally breathable, ultra-soft, and made to support skin and hormone health.

5% Elastane with Fully Covered Waistband: Added stretch for a perfect fit.

Care Instructions:

  • Machine wash on gentle with cold or warm water (max 40°C).
  • Use mild detergent. Avoid bleach or fabric softener.
  • Tumble dry low or hang dry
  • Do not iron.

For best results and long-lasting softness, we recommend hand washing in cold water.

Shipping & Returns

Fast, Reliable Delivery

We ship via USPS with tracking. Your order will arrive in 2–8 business days once it leaves our warehouse.

Fertility Fit Guarantee

Multi-packs include a 30-day risk free fit trial. One pair may be worn to assess comfort and sizing. If it isn’t a match, return the try-on pair along with the remaining unopened pairs for a full refund or store credit.

Note: Single-pair orders are final sale and not eligible for refund if worn or washed due to hygiene standards.

Free First Time Exchange

First-time multi-pack orders qualify for one free size exchange, including shipping coverage.

View full details

Why 500+ Couples Are Switching to Mr. Fertyl

Real stories from couples protecting swimmers the smarter way.

"I'm Literally Throwing Out His Old Ones Because These Are Just Better."

"Seriously, Once You Try These, You Won't Go Back."

"Consider This Your Sign To Upgrade. You'll Feel The Difference."

"Never Going Back To The Cheap Stuff."

Clinically Safe. Planet Friendly. Couple Approved.

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Oeko-Tex® Certified

Lab-tested safe. No harmful chemicals. Gentle on skin.

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Fertility Fit Guarantee

30-day risk-free trial. Designed to protect your fertility.

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Low Environmental Impact

99% closed-loop process. Less waste. Cleaner planet.

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Sustainably Sourced Materials

Responsibly grown bamboo. Better for your body and the Earth.

Not All ‘Natural’ Underwear Protects Sperm

Mr. Fertyl

Organic Cotton

Traditional Underwear

Designed For Sperm Health

Doesn’t Trap Heat

No Toxins on Skin

Protects Most Sensitive Area

No Microplastics

High Impact Sustainability

Built To Last

Bonus Gift: The Fertility Blueprint ($30 Value)

  • Delivered instantly to help start improving sperm health today.


    ✓ The 90-Day Sperm Regeneration Timeline
    Understand how long it takes and what actually improves results


    ✓ Fertility-Boosting Foods & Drinks
    Backed by clinical research to support sperm motility and count.


    ✓ Daily Habits, Exercises & Supplements
    Simple shifts that optimize male reproductive health


    ✓ Toxins, Plastics & Chemicals to Avoid
    What’s silently sabotaging sperm and how to detox fast


    ✓ Lifestyle Tweaks That Actually Work
    From sleep and heat exposure to tight clothing and beyond


    This is the blueprint to reset reproductive health from the inside out. Trusted by real couples. Designed to support long-term fertility goals.

Top Questions From Couples On Their TTC Journey

Bamboo Lyocell fabric keeps testicular temperature safely below the heat-damage threshold, shields skin from microplastics and endocrine-disrupting chemicals, and eliminates waistband contact with exposed elastane.

Harvard research shows men in looser, cooler underwear averaged up to 25% higher sperm concentration and 17% higher sperm count; every design element of this boxer replicates those conditions daily.

Sperm regenerate roughly every 72-90 days. Although no underwear can guarantee improved fertility, a Harvard study found that men who wore looser, cooler underwear had 25% higher sperm concentration and 17% higher total count compared to those in tighter styles. Switching to temperature-regulating, toxin-free underwear today allows the next complete sperm cycle to develop under optimal conditions.

Every hour in toxic underwear exposes sperm to excess heat and synthetic chemicals that may impair motility, morphology and count. A Harvard study found men who wore looser, cooler underwear had 25% higher sperm concentration and 17% higher total count. Sperm regenerate every ~72–90 days, which means damage compounds silently over time. With IVF costs reaching $15,000 per cycle, this simple switch offers daily protection during the most critical window—before regret becomes reality.

Organic cotton is a better option than synthetics, but it still traps heat and moisture—two key factors known to impair sperm quality.

Conventional cotton does the same while also shedding lint-sized fibers and often retaining pesticide or dye residues.

In contrast, closed-loop Bamboo Lyocell is three times more breathable, uses one-third the water, and holds the highest OEKO-TEX® Class 1 safety certification. A covered waistband ensures no elastane ever touches skin, and high-strength cellulose fibers extend durability. Producing this fertility-safe fabric costs more than sewing basic cotton—but offers protection far beyond a drawer full of cheaper pairs and the rising $15,000-per-cycle cost of IVF.

Each purchase is covered by a 30-day Fertility Fit Guarantee. One pair may be tried on; if sizing is incorrect, a free exchange is provided and all unworn pairs remain eligible for a full refund or store credit.

We ship from the U.S. within 1 business day. Most orders arrive in 2–5 business days, and you’ll get tracking the moment it ships.

Why Experts Warn About Heat, Toxins, and Tight Underwear

Men occupationally exposed to BPA have shown decreased sperm quality, reduced libido and higher rates of erectile dysfunction.

Dr. Shanna Swan, PhD

Award-Winning Scientist Based at Mt. Sinai (New York, NY)

If men wear tight underwear, the temperature around the testicles is increased, and that can have detrimental effects on the quality and the number of sperm.

Dr. Alex Polyakov, MBBS

Clinical Director of Melbourne IVF and Senior Lecturer at University of Melbourne

Any exposure [to heat] that significantly increases temperature is likely to affect spermatogenesis (sperm production)…

Dr. Jorge Chavarro, MD, ScD

Associate Professor of Nutrition and Epidemiology at Harvard T.H. Chan School of Public Health

PFAS can disrupt our reproductive hormones and have been linked with delayed puberty onset and increased risks for endometriosis and polycystic ovary syndrome.

Dr. Damaskini Valvi, MD, PhD, MPH

Assistant Professor of Environmental Medicine and Public Health at Mount Sinai and Nationally Recognized PFAS Expert

These days, polyester is a commonly used synthetic material for underwear. It has been shown to hold in heat and is less breathable than other materials. The testicular temperature may rise due to such material, leading to scrotal heat stress.

Dr. Akta Bajaj, MBBS, MD 

Senior Consultant & Head of Obstetrics & Gynecology at Ujala Cygnus Group of Hospitals

Polyester is basically plastic and can break down into microplastics, which can release a lot of chemicals that can be absorbed effectively from the scrotal skin.

Dr. Arunima Haldar, MD, MBBS

IVF & Reproductive Medicine Specialist

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Fertility Protection Starts Now

  • ➤ Sperm regenerates every ~72 days. Clothing choices made today directly influence sperm quality months later.


    ➤ Heat, toxins, and pressure reduce sperm quality.     Conventional underwear increases scrotal temperature and chemical exposure.


    ➤ Fertility-boosting changes don’t have to be complicated.     Switching to non-toxic, breathable materials is one of the simplest steps available.


    ➤ Designed with reproductive health in mind.     Every thread, fiber, and seam was selected for maximum comfort and fertility support.