Can Underwear Cause ED? What Every Man Needs to Know

Written By The Mr. Fertyl Research & Education Team

It’s an unusual question, but one that more men are asking: Can your underwear choice really cause erectile dysfunction (ED)? In a world where we’re finally opening up about men's health – from fertility to hormones and everything in between – even something as simple as boxers vs. briefs is worth talking about. Let’s dive into the science and myths behind underwear, fertility, and ED in a friendly, no-judgment zone. We’ll see what the research says, normalize the conversation around male fertility, and discover why breathable, toxin-free materials (like bamboo!) might be your new best friend down under.

The Underwear-ED Myth (and Why It Exists)

First, let’s clear the air: there’s no solid evidence that tight underwear directly causes ED. Urologists confirm this is more myth than reality [1][2]. ED – the difficulty achieving or maintaining an erection – is usually caused by issues with blood flow, nerves, hormones, or psychological factors, not whether you prefer briefs or boxers. Common causes of ED include cardiovascular disease, diabetes, smoking, and other health issues, whereas underwear type has never been listed as a direct culprit [1]. As Dr. Robert Eisenberg (urologist) points out, “boxers or briefs have never been linked directly to ED” [1].

So why do people even think tight underwear could cause ED? The idea likely comes from the fact that very tight garments might impair circulation or nerve function in the groin. In extreme cases, constant pressure could cause numbness (just as long bicycle rides can) [1]. But normal underwear, even snug briefs, don’t compress blood vessels enough to cause ED. In other words, wearing tight underwear won’t suddenly give you ED – so you can breathe easy on that front.

However, this isn’t the whole story. The reason this myth persists is that underwear does affect other aspects of men's sexual health – especially fertility. And male fertility is an important piece of the puzzle that deserves more attention. Let’s talk about that, because it turns out your choice of underwear can impact things like sperm health, which in turn ties into overall hormonal health and well-being.

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Tight Underwear and Male Fertility: The Heat Factor

While your briefs won’t make or break an erection, they can influence your fertility. The key issue is heat. Unlike the rest of your body, the testes hang outside in the scrotum for a reason – they need to stay a few degrees cooler than core body temperature for optimal sperm production [6]. Snug underwear holds the testicles closer to the body, potentially raising scrotal temperature and impairing sperm production. In fact, research shows that even a small temperature increase can have consequences. In one study, just a 1°C rise in daytime scrotal temperature was associated with a 40% drop in sperm concentration (a huge decrease) [4]. Elevated scrotal heat can slow down or damage the sperm-making process, leading to fewer and less motile sperm [4][6]. Essentially, hotter testes = struggling “swimmers.”

Multiple studies have backed this up. A famous 2018 study at Harvard (Mínguez-Alarcón et al., 2018) compared men who usually wore boxers vs. tight underwear. The boxer-wearers had 25% higher sperm concentration and 17% higher total sperm count than men who primarily wore tighter briefs [3]. They also had lower levels of follicle-stimulating hormone (FSH) on average, suggesting their bodies weren’t working overtime to compensate for heat-stressed testicles [3]. Other research over the years consistently finds that loose, breathable boxers help keep sperm counts up, whereas tight underwear can mildly impair sperm production [3][6]. Even if the differences aren’t night-and-day, they’re enough that couples struggling to conceive are often advised to choose boxers over briefs.

Quick fact: An increase in scrotal temperature of just a few degrees can inhibit spermatogenesis (sperm formation) and even cause sperm DNA damage [6]. No wonder hot tubs and saunas are linked to temporary drops in sperm count – the same principle applies to overly warm underwear environments.

It’s worth noting that not all experts see underwear as a make-or-break factor. The Mayo Clinic, for example, notes that while briefs can raise testicular temperature slightly, there’s no definitive proof that this modest uptick significantly affects male fertility outcomes [5]. So, wearing briefs isn’t birth control by itself. That said, considering how male factors contribute to about 50% of infertility cases [11], any edge in keeping sperm healthy is worth considering – especially one as easy as swapping your underwear style.

Beyond Sperm Counts: Blood Flow and Hormones

Fertility is the headline here, but you might wonder: could tight underwear affect other aspects of sexual health, like hormones or circulation? The answer is a cautious maybe. Tight waistbands or leg bands could, in theory, impede blood flow if they’re extremely constrictive – but typical underwear isn’t tight enough to significantly reduce genital blood circulation. So, impaired blood flow is not a big concern unless your underwear is truly uncomfortably tight. (If it leaves deep marks on your skin or hurts, it’s too tight – and you should size up for general health and comfort.)

Hormones are another piece of the puzzle. Testosterone, the hormone behind sex drive and sperm production, is produced in the testes. Overheating the testes could potentially affect hormone production, but studies so far haven’t shown dramatic effects on testosterone from wearing tight underwear alone [4]. In the scrotal temperature study mentioned earlier, sperm counts dropped with heat, but testosterone levels didn’t significantly change [4]. So, your undies probably won’t tank your T levels by themselves.

That said, what can influence hormones are environmental toxins and chemicals. And here’s where the type of fabric your underwear is made of enters the story. Certain materials (especially synthetics) can expose you to chemicals that might disrupt hormones. For example, a class of chemicals called phthalates – used to make plastics flexible and sometimes found in clothing materials or waistbands – are known to have anti-androgenic effects. High exposure to phthalates has been linked to lower testosterone levels in men [9], which can contribute to reduced libido and sexual function [9]. In other words, it’s not the tightness of the underwear but potentially the chemicals in or on the fabric that could sneakily impact your hormones. This brings us to an important consideration: what your underwear is made of.

Materials Matter: Synthetic vs. Natural Fabrics

Take a peek at the tag on your underwear. Is it polyester or nylon? Or cotton, bamboo, etc.? The fabric choice might influence both your reproductive health and the environment. Synthetic fabrics (like polyester) have raised some concerns in research. Believe it or not, an experiment back in the 1990s found that dogs made to wear polyester underwear had a significant decrease in sperm count and more abnormal sperm compared to dogs in cotton undies [7]. The theory was that polyester’s electrostatic properties or heat retention impaired spermatogenesis. Follow-up studies by the same researchers even suggested that men wearing polyester underwear could experience reduced sperm counts and lower libido (a bold claim that hasn’t been extensively replicated, but intriguing nonetheless). While this research is old and a bit quirky (polyester-clad dogs, anyone?), it highlights that fabric can have biological effects.

More concretely, scientists today focus on chemical additives in fabrics. Polyester and other synthetic textiles can contain residues of chemicals like PFAS (used for water-resistance), BPA, phthalates, and flame retardants from manufacturing [7]. Many of these are known endocrine disruptors and reproductive toxins. For instance, PFAS chemicals (the “forever chemicals”) have been linked to a reduction in fertility. The NIH’s environmental health institute reports that high levels of PFAS in blood were associated with up to a 40% decrease in fertility in women (delayed pregnancy and higher risk of issues like PCOS) [7][8]. Phthalates, as mentioned, are associated with lower testosterone and have been linked to poorer fertility and higher miscarriage rates in some studies [7]. BPA, another plastic chemical sometimes found in synthetic-blend fabrics, can also interfere with hormonal balance and has been tied to hormonal disorders in women [7] (and we certainly don’t want these chemicals rubbing on sensitive areas every day!).

To be clear, your underwear alone isn’t going to poison you – drinking water and other sources are bigger routes of exposure for things like PFAS and BPA [7]. But if you’re health-conscious or trying to maximize fertility, it makes sense to minimize unnecessary chemical exposure wherever you can. Clothing is one exposure you can control. Choosing natural, toxin-free materials means you’re avoiding one more source of potential hormone-disrupting chemicals.

The Case for Breathable, Natural Underwear (Hello, Bamboo!)

By now, it’s clear that breathability and no toxicity are the winning combo for underwear that supports male reproductive health. Natural fabrics like cotton have long been recommended for their comfort and airflow. An even more modern option is Bamboo Lyocell, a sustainable fabric that’s making waves in men’s health circles. Brands like Mr. Fertyl have introduced bamboo underwear lines to give men a cooler, cleaner alternative to synthetics. So, what’s so special about Bamboo Lyocell?

For one, Bamboo Lyocell is highly breathable and moisture-wicking [10]. This means it helps keep your groin area cool and dry by allowing air circulation and pulling sweat away from the skin. Less sweat and heat = happier testicles, which could help maintain optimal sperm production. The material is also naturally thermoregulating, so it adjusts with your body temperature to prevent overheating. If you’ve ever worn cheap polyester boxers that made you sweat, you’ll appreciate how bamboo fabric stays breezy.

Secondly, Bamboo Lyocell is typically produced without harsh chemicals. Unlike standard bamboo viscose that uses toxic solvents, the Lyocell process is a closed-loop, eco-friendly method with nontoxic solvents [10]. The result is a clean fabric free of residues like formaldehyde or chemical finishes. You’re essentially wrapping your privates in a toxin-free zone. This is great for sensitive skin and ensures you’re not leaching weird chemicals onto yourself all day.

Let’s not forget comfort and health: Bamboo Lyocell is hypoallergenic and naturally antibacterial [10]. Fewer microbes and irritants mean less risk of rashes, jock itch, or unpleasant odors. And it’s soft and smooth – no chafing here. All these qualities can indirectly benefit sexual health; when you feel comfortable and fresh, you’re more likely to feel confident and in the mood, right?

In summary, here are some key benefits of breathable, bamboo-based underwear for men:

  • Cooler Temperatures: Bamboo fabric keeps the testicular area cooler than synthetics by allowing better airflow and not trapping heat. This supports healthy sperm production and may protect fertility [6][10].
  • Moisture-Wicking: It draws sweat away from the skin and dries fast, preventing that swampy feeling. A drier environment helps avoid prolonged warmth and reduces skin irritation or fungal growth.
  • Chemical-Free Comfort: High-quality Bamboo Lyocell (like our line) is made without harmful chemicals. You avoid exposure to toxins like PFAS, phthalates, and BPA that can come with polyester blends [7]. This means less worry about hormone-disrupting substances in contact with sensitive areas.
  • Bamboo Lyocell is gentle on the skin, hypoallergenic, and resists bacterial growth [10]. This cuts down on odor and infection risk, keeping you healthier and more comfortable day to day.
  • As a bonus, choosing bamboo is better for the planet. Bamboo grows rapidly without pesticides, and the Lyocell process recycles water and solvents [10]. By wearing eco-friendly underwear, you’re supporting environmental health too, a win-win for your body and the Earth.

Taking Charge of Your Fertility and Health

Talking about underwear, fertility, and ED in the same breath might have seemed odd a few years ago. But normalizing these conversations is important. Men’s reproductive health is too often overlooked or brushed off due to embarrassment. The truth is, fertility and sexual health are key parts of overall well-being for every man – and they’re influenced by everyday choices, even the underwear you put on each morning.

Remember, ED itself is usually driven by medical factors (like circulation or nerve issues), so if you’re experiencing erectile difficulties, it’s wise to talk to a healthcare provider. Don’t blame your boxers alone for a bout of ED. However, paying attention to things like fertility and hormone health can have benefits for sexual function. Healthy testicles usually mean normal testosterone levels and sperm counts, which are good for libido and general male vitality.

Fertility is the central message here: keeping your sperm healthy and hormones balanced is not just about making babies – it’s about your hormonal health, energy, and confidence. Approximately half of infertility cases have a male factor involved [11], so it’s absolutely something men should be open about and proactive in managing. Simple lifestyle tweaks – wearing looser, breathable underwear, avoiding overheating (no laptop directly on the lap for hours, and skip the daily hot tub sessions), and steering clear of unnecessary chemical exposures – can potentially preserve your reproductive health for the long run.

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The Bottom Line

So, can underwear cause ED? Not directly, no. You won’t develop erectile dysfunction just from wearing tight briefs. But your underwear choices can affect the health of your sperm and the comfort of your nether regions, which in turn play a role in overall male sexual health. Tight, synthetic underwear can raise temperature and possibly introduce unwelcome chemicals, negatively impacting sperm quality and hormonal balance [1][7]. On the flip side, choosing breathable, toxin-free materials like Bamboo Lyocell helps keep things cool, comfortable, and clean – fostering an environment for your fertility to thrive.

The great news is that switching your underwear is one of the easiest health changes you can make. It’s as simple as opening your dresser and opting for a pair of high-quality, natural-fiber briefs or boxers. Mr. Fertyl’s bamboo underwear, for example, is designed with this exact purpose in mind: to support men’s reproductive and hormonal health by eliminating excess heat and toxins. While wearing better underwear isn’t a magical cure for ED, it is a smart step toward protecting your fertility, testosterone, and overall well-being. Consider it an investment in your “family jewels” and your future.

At the end of the day, taking care of yourself – whether that means hitting the gym, eating right, or yes, wearing fertility-friendly underwear – is what being a healthy man is all about. Don’t be afraid to talk about it either. The more we discuss men’s fertility and environmental health openly, the easier it gets to make informed choices. So go ahead, give those tight synthetics the boot, slide into something more natural, and rest easy knowing you’re doing something good for your swimmers (and maybe even for your love life). Your body will thank you for it.

  1. Eisenberg, R. (2021). Sharp Health News: Tight underwear and infertility. Source.
  2. Proxim Pharmacy. (2020). Myths about ED – Tight underwear and fertility. Source.
  3. Mínguez-Alarcón, L., et al. (2018). Human Reproduction, 33(9), 1749-1756. Source.
  4. Hjollund, N. H., et al. (2002). Reproductive Toxicology, 16(3), 215-221. Source.
  5. Mayo Clinic Health System. (2019). Boxers or briefs – fertility myths. Source.
  6. Male Infertility Guide. (n.d.). Impact of excessive heat on sperm quality. Source.
  7. Novak, S. (2025). Discover Magazine: Chemicals in fabrics and fertility. Source.
  8. NIEHS. (2023). PFAS Exposure and reduced fertility (Press release). Source.
  9. SMSNA. (2014). Phthalate exposure linked to lower testosterone. Source.
  10. Cotton Monk. (2025). Bamboo Lyocell benefits (hypoallergenic, breathable). Source.
  11. Leslie, S. W., Soon-Sutton, T. L., & Khan, M. A. B. (2024). Male infertility. In StatPearls. StatPearls Publishing. Source.