Testosterone and the Skin
Testosterone affects everything in men, so it should be no surprise that it
affects the appearance of your skin in multiple ways. Most guys aren't too
worried about their appearance, but I occasionally receive questions about it.
For example, on
the Peak Testosterone Forum, I once
received this question: "I have a reddish
nose, dry flaky skin on nose and broken blood vessels on cheek...Can low
[testosterone] give you bad skin?" 
Of course, skin condition is related to many things, including diet, sun
exposure and growth hormone. That's right - lower growth hormone levels
can actually thin the skin a little. So it's difficult to definitively say
anything without some individual experimentation. However, as I'll show
below, the flakiness could be partially related to low testosterone-related
issues. But first I want to cover the three key mechanisms whereby
testosterone has a big influence on the skin:
1. Sebum. Most of us know that testosterone can affect acne,
but are not really sure how. Testosterone is actually converted by an
enzyme called 5-alpha reductase to DHT (dihydrotestosterone). And it is
DHT that controls the sebaceous glands in the skin and the production of sebum.
Sebum is one of the things that you don't want too much or too little of.
It is composed of a variety of cellular material including fat and keratin and
is a natural lubricant for your skin and hair. However, too much sebum is
a root cause of acne.
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For this reason, there have been various anti-DHT solutions that have been
developed to help with acne, including one herbal compound that did quite well
according to one study. 
Furthermore, sometimes HRT will result in acne as a reported side effect even in
middle-aged men. (It is not common though: see my link on
Replacement Therapy for more details.) And, at least theoretically,
low testosterone could lead to low DHT, which could, in turn, lead to low sebum
levels, "asteatosis" in its extreme case, resulting in dry, scaly skin. As
always, there appears to be range that is best.
2. Estrogen (Estradiol or E2). Estrogen in males come almost entirely
from the conversion of testosterone via aromatase. (The "bad" estrogen is
estradiol or E2.)Aromatase is stored in fat
cells and, as we age, we tend to put on weight and convert more testosterone to
estrogen. This trend lowers testosterone and raises male estrogen levels over time. So that
means that low T men have high estrogen, right?
In actuality, many hypogonadal men actually end up with low estrogen levels even if they are overweight,
testosterone levels fall so far that no amount of aromatization can rescue
the situation..In fact, it is a very common problem for men with low testosterone to
actually develop osteopenia initially and later osteoporosis unless it is caught
and treated early enough. (There are other nasty problems associated with low
estrogen levels, which I cover in this link
Do Men Really Need Estrogen?) Several
studies have noted this. One in partcular found that low total testosterone was strongly
correlated to bone loss and associated with an 88% increased risk of hip and 28%
of non-spinal fractures, respectively. 
Theoretically, these low estradiol levels could also negatively impact a man's
skin as well, because estrogen is tied to collagen production. Studies
have shown, for example, that applying an estradiol cream to the skin of senior
men increased collagen proudction.  Thus, it is not unreasonable to assume
that men with lower testosterone levels could end up with decreased collagen
production and more aged skin as a result.
3. AGE's (Advanced Glycation End Products). Testosterone is very
much associated with insulin levels. In general, the more the
testosterone, the lower the insulin levels. As I point out in my book
Testosterone by the Numbers, low testosterone leads to decreased insulin
resistance and elevated glucose levels.  This is why hypogonadism is
associated so strongly with diabetes and Metabolic Syndrome. One HRT clinic
that I talked to said that all their men on testosterone therapy had
been able to completely get off of insulin. (A few still had to take
Metformin but, still, it is remarkable that they could completely eliminate
their insulin regimen.)
The point here is that lower testosterone will tend to raise both insulin and
glucose levels, which could lead to accelerated AGE's. AGE's are glycated
proteins that accumulate and age various tissues. This is one of the
reasons that diabetes is such a debilitating disease: it ages many, many
tissue due to this whole issue. The skin is no exception and can age
overly rapidly from this as well. See my link on
Advanced Glycation End
Products for more information.
So, really, the bottom line is that, although high testosterone can lead to acne
in some sensitive men, lower testosterone levels may be even more problematic,
leading to accelerated aging of the skin via decreased collagen production and
lubrication along with and increased levels of glycated
proteins. As always, I urge men to
Get Tested Regularly for Testosterone
2) Clin Endocrinol (Oxf), 2005 Sep, 63(3):239-50, "Androgens, insulin resistance
and vascular disease in men"
3) Arch Intern Med, 2008, 168(1):47-54, "Endogenous Sex Hormones and Incident
Fracture Risk in Older Me: The Dubbo Osteoporosis Epidemiology Study"
4) Arch Dermatol, 2008, 144(9):1129-1140, "Induction of Collagen by Estradiol:
Difference Between Sun-Protected and Photodamaged Human Skin In Vivo"
6) European Journal of Integrative Medicine, Nov 2008, 1(suppl 1):40, "Dermal
application of a Cimicifuga racemosa (CR)-containing cream has beneficial
effects on acne"