Wearing briefs boosts erectile dysfunction risk, 26,000-man study in China finds

From A-list underwear campaigns to everyday wardrobe staples, tight briefs are often hailed as the ultimate symbol of masculine appeal.

However, a major new study out of China suggests that choosing tight underwear over classic boxer shorts could lead to higher rates of erectile dysfunction, premature ejaculation and prostatitis.

A snug fit also impairs sperm quality, according to the findings published in the Asian Journal of Andrology last month.

Loose underwear may offer a simple alternative to “protect semen quality and sexual function”, corresponding author Dr Wu Limin wrote in the paper.

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Wu is a researcher and doctoral supervisor at the Centre for Reproductive Medicine at the First Affiliated Hospital of the University of Science and Technology of China.

Between July 2019 and May 2025, her team recruited 42,054 men from hospital reproductive clinics who were seeking fertility evaluations. Ultimately, 26,836 were enrolled – creating a cohort more than 40 times larger than a similar Harvard study.

The 2018 Harvard study involving 656 men suggested that boxer wearers had higher sperm counts, but an earlier British study had reached the opposite conclusion, leaving the debate in a scientific stalemate.

This deadlock has now been broken by the Chinese researchers.

Among the nearly 27,000 volunteers, as many as 21,221 habitually wore loose-fitting underwear, while 5,615 usually wore tight-fitting styles such as boxer briefs, Y-fronts or thongs. This information on underwear type was self-reported by the participants through a questionnaire.

Each participant was also required to complete questionnaires on erection issues and premature ejaculation, as well as to have their semen quality tested.

The screening questionnaires revealed greater erectile and ejaculation issues among those who regularly wore tight underwear.

Tight-fitting underwear was associated with a higher prevalence of erectile dysfunction (62.7 per cent versus 57.8 per cent) and premature ejaculation (30.8 per cent versus 23.2 per cent) than looser styles. In sperm testing as well, the looser underwear group performed better.

Men who wore loose underwear had slightly higher average sperm counts (63.9 million per millilitre compared to 60.5 million) and slightly better sperm movement (46.3 per cent compared to 44.1 per cent) than the tight underwear group. The boxers group also performed better on the remaining semen parameters.

“This large cross‑sectional analysis revealed that [tight underwear] was associated with modest reductions in several semen parameters (5 per cent to 10 per cent) and a higher prevalence of erectile dysfunction and premature ejaculation based on screening questionnaires,” according to the paper.

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The researchers also looked at how underwear style related to lifestyle habits and health conditions. They found that men who wore tight underwear were more likely to smoke, drink alcohol, and have conditions like varicocele and prostatitis.

The authors acknowledged that this was a single-centre cross-sectional study and therefore required further exploration – but the findings do constitute some of the strongest evidence to date on underwear and semen quality.

“[Tight underwear] was associated with poorer semen quality and a higher prevalence of erectile dysfunction and premature ejaculation. Choosing [looser underwear] may represent a simple, modifiable approach to help protect semen quality and sexual function,” Wu concluded in the paper.