Dr. Michael Eisenberg: A urologist at Stanford specializing in male sexual function and fertility, with over 300 peer-reviewed publications. He is considered one of the world's foremost experts in male sexual health.
What this episode covers
Andrew Huberman interviews urologist Dr. Michael Eisenberg about the full landscape of male sexual and reproductive health. They cover whether sperm quality and testosterone are truly declining, the surprising finding that penile length is increasing while sperm counts fall, and the role of obesity, heat, smoking, alcohol, cannabis and cycling. Eisenberg explains that fewer than 10% of erectile dysfunction cases are hormonal, with most being vascular, and walks through treatments from PDE5 inhibitors to injections and penile implants. The conversation also covers prostate health, fertility testing, paternal age and autism risk, finasteride side effects, and why semen quality may be a 'sixth vital sign' for overall health.
Also referenced (named, not recommended)
Tadalafil (Cialis)
Eli Lilly
“low dose of tadalfil these two and a half to 5 milligram these daily dosing um can help with these urinary symptoms”— Michael Eisenberg
Sildenafil (Viagra)
Pfizer
“the fact that these drugs like toal Phil also called Calis right is seal the brand name right okay and Viagra is that a brand name right stands for what is the generic name oh selenop”— Michael Eisenberg
Stendra (avanafil)
Metuchen Pharmaceuticals
“so usually we start with oral therapy so phosph phosphodiester inhibitor therapy so that would be like selenop or viag talil seis ail Stendra venil litra”— Michael Eisenberg
Levitra (vardenafil)
Bayer
“so that would be like selenop or viag talil seis ail Stendra venil litra and would you be willing to talk about some of the specifics”— Michael Eisenberg
Xiaflex (collagenase)
Endo Pharmaceuticals
“now there's an FDA approved medicine for it collagenase or zlex which is a medicine that disolves scar tissue um so that's one of the treatments we have for it”— Michael Eisenberg
Finasteride
Merck
“before it was FDA approved for that indication at least finasteride was you know they did randomized control trials to look”— Michael Eisenberg
Dutasteride
GlaxoSmithKline
“the drugs that many people take to suppress dihydro testosterone in hopes to keep or grow their hair things like finasteride dutasteride”— Andrew Huberman
Clomiphene (Clomid)
Sanofi
“chopine is a selective estrogen receptor modulator so basically it blocks estrogen and so from our earlier discussions of how the pituitary works”— Michael Eisenberg
Big reveals from this episode
- Reveals only a very small percentage of erectile dysfunction stems from hormone dysfunction; most is vascular or neural.
- States less than 10% (around 5%) of erectile dysfunction is due to endocrine/hormonal issues, a shock given testosterone hype.
- His study of 55,000 men found penile length is increasing over time, the opposite of what the team expected.
- Calls semen quality the 'sixth vital sign', a barometer for cancer, diabetes, heart disease and longevity.
- Confirms post-finasteride syndrome can be permanent in a handful of men, with treatment-refractory sexual dysfunction.
- Notes only about a quarter of Danish men sampled had normal semen quality.
- About 1 in 20 infertile men are that way because they are on testosterone therapy.
Worth remembering
- Men contribute to infertility about half the time, yet the man is bypassed in evaluation roughly a third of the time.
- Roughly two new mutations accumulate in sperm DNA per year, so a 40-year-old carries ~20-40 more than a 20-year-old.
- Average paternal age in the US rose from about 27.5 to 31 over the last 40 years.
- The oldest recorded father conceived a child at age 96.
- Testosterone peaks in the early 20s and declines roughly 1% per year thereafter.
- FSH works for sperm production but costs $2,000-3,000/month versus $300-500 for HCG, so HCG is used instead.
- A varicocele (dilated scrotal veins) affects about 1 in 7 men and causes 30-40% of infertility cases.
- Over half of men over 40 have some erectile trouble; under 40 it's about 15-20%.
- Obesity explains only about a 10% decline in semen quality, far short of the purported ~50% overall decline.
- National guidelines actually recommend against routine testicular self-exams due to false-alarm anxiety.