The main cooling underwear approaches are ice-pack designs, loose natural-fiber styles, and breathable TENCEL-based underwear built for airflow. For everyday wear, fabric and fit do most of the work. Ice-pack designs add active cooling but require prep and maintenance.
The category has gotten crowded fast. You'll find everything from cotton boxers to underwear with reusable gel inserts to technically engineered briefs made from wood-pulp fibers. Each approach makes a version of the same promise. They don't all deliver it the same way, and the differences matter depending on how you actually live.
The main approaches and what each one actually does
Here's a plain comparison of the four design categories you'll encounter.
| Approach | How it works | Practical tradeoff |
|---|---|---|
| Ice-pack / gel-insert designs | A reusable cold pack slots into a pouch. Active cooling for 20-40 minutes. | Requires freezing, prep, and a change of routine. Not wearable all day. |
| Loose cotton boxers | Airflow from relaxed fit. No compression. Familiar feel. | Cotton holds moisture. In heat or after exercise, it stays damp and warm. |
| Synthetic performance briefs | Wicks sweat quickly. Compressive fit keeps things in place. | Compression adds heat. Synthetics can trap warmth against skin. [1] |
| TENCEL-fiber briefs (relaxed fit) | Wood-pulp-derived fibers move moisture away. Relaxed cut allows airflow without bulk. | No active cooling. Works passively, all day, without prep. |
What the research says about fit and genital temperature
A large study of 656 men attending a fertility clinic found that men who primarily wore boxers had meaningfully higher sperm concentration than men in tighter styles. [2] A separate narrative review tied garment fit directly to scrotal thermoregulation, noting that constrictive underwear raises local temperature in ways that looser cuts avoid. [3] The mechanism isn't complicated: compression holds the area closer to the body and reduces the airflow that normally helps it stay cooler than the rest of you.
Fabric matters alongside fit. Natural and naturally derived fibers consistently outperform synthetics on moisture management and sensory comfort in peer-reviewed textile comparisons. [1] That gap widens in heat.
- Fit: relaxed beats compressive for airflow, full stop.
- Fabric: moisture-wicking natural or naturally derived fibers outperform cotton and synthetics in sustained heat.
- Active cooling inserts: useful for targeted, short-duration cooling, but not a substitute for daily wear choices.
If you want to read more about how tight underwear specifically affects the biology, the detail is here: Can wearing tight underwear reduce male fertility?
Oakman launches Fall 2026. Founding members get first access and founding pricing locked in. Reserve your spot.
Where Oakman fits in this category
Oakman is built specifically for active men looking for scrotal cooling all day and want the option of a cold pack for cooling in the sauna or after heat exposure. The fabric is TENCEL MicroModal, naturally derived from wood pulp rather than plastic, blended with ROICA V550, a clean Japanese stretch fiber, rather than conventional spandex. The fit is athletic with a gusset, an extra panel that gives the testicles room and airflow. Dyes are bluesign approved, so what touches your skin is controlled all the way through the supply chain.
Oakman launches Fall 2026. The Founding 100 get first access, along with a reusable cooling pack designed as a sauna companion. If the fabric-and-fit approach fits how you live, the waitlist is the place to start.
Related reading
Frequently asked questions
Does underwear style actually affect scrotal temperature?
Yes, the evidence is consistent. Tighter styles hold the genital area closer to the body and reduce the airflow that helps it stay cooler. Looser fits and more breathable fabrics measurably reduce that effect. [3]
Are gel-pack cooling underwear designs worth it?
They deliver real, active cooling for a short window, which some men find useful for targeted sessions. The tradeoff is the prep routine: you need to freeze the pack and swap it out. They're not designed for all-day wear.
Is cotton or synthetic better for staying cool down there?
Cotton breathes better than most synthetics but holds moisture once it's damp, which works against you in heat. Naturally derived fibers like MicroModal and Lyocell move moisture away more efficiently and tend to feel drier against skin. [1]
Does underwear fabric affect fertility?
The research links elevated genital heat to lower sperm quality, and garment fit and fabric influence local temperature. [2] No underwear brand can promise a fertility outcome, but the underlying biology is well-documented.
What should I look for if I'm trying to conceive?
A relaxed fit and a breathable, moisture-wicking fabric are the two variables with the most support in the literature. You might also find this useful: Alternatives to IVF for Male Infertility.
This article is for general educational purposes and is not medical advice. If you have specific concerns about fertility or your health, talk to a qualified clinician.
References
- Comparative Assessment of Sensory Comfort Properties Across Eco-Friendly Textile Materials for Apparel. 2025. Journal of Natural Fibers (Taylor & Francis). [Link]
- Minguez-Alarcon L, et al.. (2018). Type of underwear worn and markers of testicular function among men attending a fertility center. Human Reproduction. [Link]
- Zleczewski, et al.. (2024). Garment fit, scrotal thermoregulation, and male fertility outcomes: a narrative review. Translational Andrology and Urology. [Link]
