The Science
The Science
Most men don't know heat is destroying their sperm
Heat is one of the few reversible causes of male infertility — and one of the most ignored. Here's what decades of clinical research actually shows.
Without cooling vs. with IcySack
Without cooling
With IcySack
This is one of the few reversible causes of male infertility
Unlike genetic causes or anatomical issues, heat-related sperm damage responds directly to intervention. The biology is clear — and so is the solution.
48–66%
of men showed improved sperm count with scrotal cooling
Mulcahy et al., review of 8 studies
28–83%
improvement in sperm motility and morphology
Jung et al., 2001 & 2005
1–2°C
below core body temp required for healthy spermatogenesis
Hjollund et al., 2000
90%
potential reduction in sperm count from sustained heat
Robinson et al., JAMA 1968
The Core Problem
Why scrotal temperature matters more than most men realise
Key takeaways:
- Spermatogenesis requires 1–2°C below core body temperature
- Modern habits constantly push scrotal temperature above this threshold
- Even brief, repeated heat exposure impairs sperm DNA integrity
- This damage is reversible with consistent cooling
The testes are located outside the body for a specific biological reason — sperm production is exquisitely sensitive to temperature. The optimal range is 1–2°C below core body temperature, around 34–35°C.
When scrotal temperature rises above this range — even briefly and repeatedly — it directly impairs the DNA integrity and production rate of sperm. Modern lifestyle consistently works against this biology.
Laptop computers placed on the lap raise scrotal temperature by up to 2.7°C in under an hour. Prolonged sitting, tight underwear, and sedentary work all compound the problem daily.
Most men experiencing heat-related fertility issues have no idea the problem exists — or that it's fixable.
Scrotal temp change by activity
The Mechanism
How L-menthol creates cooling without ice
In plain english:
- L-menthol tricks your skin's cold receptors into signalling "cold"
- This lowers the perceived and actual temperature of the scrotal area
- No refrigeration, no discomfort — just consistent nightly cooling
L-menthol cooling pathway
L-menthol (0.5%)
in hydrogel patch
Binds TRPM8
cold receptor in skin
Cooling signal
sent to nervous system
Scrotal temp ↓
toward 34–35°C
Better sperm
over 90 days
Sustained 6–8 hour release
The hydrogel matrix releases L-menthol slowly and consistently through the night — maintaining the cooling signal throughout sleep without needing replacement.
No ice, no refrigeration required
The cooling effect is entirely pharmacological. Previous scrotal cooling devices required ice packs or refrigeration — the L-menthol patch removes this barrier to daily compliance.
Cumulative effect over 90 days
Consistent nightly cooling across a full spermatogenesis cycle (72–90 days) gives the body the sustained temperature environment needed to produce measurably healthier sperm.
The 90-Day Protocol
The clinical protocol maps directly to a purchase decision
Spermatogenesis takes 72–90 days. That's not arbitrary — it's the biology. One full cycle of consistent nightly cooling is what the research is built around.
Your 90-day timeline
Day 1–14
Routine established
Cooling active from night one. Building the habit.
Week 3–4
Early changes
Some men note early improvements in studies from week 2.
Week 6–8
Significant change
Statistically significant sperm count improvements from week 8.
Day 90
Full cycle complete
Optimal time for semen re-analysis. One full spermatogenesis cycle.
1 patch
per night
~90 applications
for full protocol
3–4 packs
recommended to complete
The Clinical Trial
The SCOP Trial — University of Nottingham
A randomized controlled trial specifically designed to test this exact product category — the most rigorous study of scrotal cooling patches published to date.
Study Design
RCT at Nottingham University Hospitals NHS Trust — the gold standard of clinical evidence.
What Was Measured
A comprehensive range of male fertility markers — the full picture.
Who Was Included
Men aged 18–45 with real fertility challenges — not healthy volunteers.
The Protocol
Closely mirrors real-world IcySack use — what the research tested is what you're doing.
Published Research
The primary paper & key findings
The SCOP trial protocol was published as an open-access paper in the peer-reviewed journal Trials. Here's the paper and what the broader cited literature found.
Published Paper
A study of the effect of the FertilMate™ scrotum cooling patch on male fertility
The SCOP trial investigated whether exposing the scrotum to lower temperatures using the Babystart FertilMate hydrogel patch could improve fertility by improving semen parameters, and assessed the feasibility of a full clinical trial in a UK university teaching hospital fertility clinic.
Sperm Count
48–66%
of men in reviewed studies showed improved sperm count. Improvements noted as early as 2 weeks in oligospermic men.
Motility & Morphology
6 of 8
studies showed improvement in sperm motility, morphology or both — with ranges of 28–83% improvement.
Significant change from
Week 8
Statistically significant increases in sperm count observed from 8 weeks of consistent nightly scrotal cooling.
Also tracked
Testosterone
The SCOP trial measured testosterone, FSH, and LH — recognising the link between testicular temperature and endocrine function.
Real Customers
Men following this protocol
The science is compelling. Here's what real customers say after completing or following the 90-day protocol.
"After 8 weeks my sperm analysis improved significantly. This was the only change I made to my routine. My doctor was surprised."
"My wife and I had been trying for over a year. Doctor mentioned heat as a factor. Three months on these patches and we got pregnant naturally."
"I sit at a desk all day and use a laptop constantly. Motility count was low. After 90 days on the protocol my numbers improved across the board."
1,000+ men currently following the IcySack 90-day protocol
Supporting Literature
Key studies cited in the SCOP trial
What this research consistently shows:
- Scrotal temperature directly impacts sperm quality
- Cooling improves key fertility markers across multiple independent studies
- Effects are measurable within 8–12 weeks of consistent application
| Authors | Year | Method | Key Finding |
|---|---|---|---|
| Robinson, Rock & Menkin | 1968 | Induced scrotal temp changes | Demonstrated direct control of spermatogenesis via temperature manipulation |
| Zorgniotti, Seaflon & Toth | 1980 | Chronic scrotal hypothermia | Improved semen quality in subfertile men — published in The Lancet |
| Zorgniotti et al. | 1986 | Scrotal hypothermia — 90 couples | Significant improvements in sperm parameters across 90 infertile couples |
| Jung, Eberl & Schill | 2001 | Nocturnal scrotal cooling + lifestyle | Improved sperm quality in oligoasthenoteratozoospermia |
| Jung, Schill & Schuppe | 2005 | Nocturnal cooling | Semen quality improvement in men with history of testicular maldescent |
| Hjollund et al. | 2000 | Diurnal scrotal skin temperature | Established direct correlation between scrotal temperature and semen quality |
| Sheynkin et al. | 2005 | Laptop computer users | Laptop use significantly raises scrotal temperature — Human Reproduction |
| Mulcahy | 1984 | Scrotal hypothermia review | Comprehensive review establishing scrotal cooling as infertility treatment |
Full references: Osman et al. (2012). Trials 13:47. doi:10.1186/1745-6215-13-47
Safety & Suitability
Who should and shouldn't use IcySack
The SCOP trial established clear inclusion and exclusion criteria. We follow the same guidelines.
Suitable for
Men aged 18–45 with suboptimal sperm parameters, men actively trying to conceive who want to eliminate heat as a risk factor, and men looking to optimise reproductive health.
Active ingredient
0.5% w/w natural L-menthol in a non-greasy hydrogel matrix. Slim, flexible, trimmable, no refrigeration needed. The cooling is pharmacological — not temperature-based.
Do not use if
You have a known allergy to menthol, have undergone vasectomy or genital surgery, have diabetes, hypertension, or another chronic medical condition. Consult your physician if unsure.
Lower temperature. Support sperm health. Start tonight.
One patch every night. 90 days. Clinically backed cooling for male fertility.