The Biology of Hormonal Skin Behaviour
THE BIOLOGY OF HORMONAL SKIN AGEING
(How each hormone influences collagen, elasticity, inflammation, pigment, oil, and skin behaviour)
THE SKIN IS A HORMONE-DEPENDENT ORGAN
Hormones control nearly every visible change in the skin:
- firmness
- thickness
- elasticity
- inflammation
- redness
- oil activity
- hydration
- pigment
- healing
- sensitivity
- texture
- collagen and elastin production
When hormones shift, skin behaviour shifts immediately.
Page 5B explains each major hormone and its effect on the skin.
OESTROGEN — THE COLLAGEN-PROTECTOR
Oestrogen is the hormone most responsible for youthful skin.
It increases:
- collagen production
- elastin density
- fibroblast activity
- ECM hydration
- hyaluronic acid
- vascular health
- wound healing
- barrier strength
- antioxidant protection
Oestrogen declines begin as early as age 32–35, accelerating from 40–55.
The consequences are dramatic:
- 30% collagen lost in the first 5 years of menopause
- increased laxity
- thinning dermis
- crepey texture
- slower healing
- increased redness
- deeper lines
- under-eye collapse
- neck ageing
- mouth-area ageing
This is one of the biggest drivers of female structural ageing.
PROGESTERONE — THE SENSITIVITY HORMONE
Progesterone influences:
- water retention
- barrier function
- oil activity
- inflammation
Low progesterone (common from mid-30s onward):
- increases sensitivity
- increases inflammation
- increases redness
- weakens the barrier
- increases dryness
- increases irritation
- worsens rosacea-type reactions
In perimenopause, progesterone fluctuations cause skin to feel “all over the place.”
TESTOSTERONE — THE STRUCTURAL & OIL HORMONE
Testosterone increases:
- dermal thickness
- collagen density
- structural strength
- jawline definition
- muscle support under the skin
- oil activity (sebum)
In women:
Low testosterone →
- thinning skin
- low glow
- decreased firmness
- reduced oil (dryness)
- accelerated ageing
In men:
Testosterone decline (andropause) →
- heavy sagging
- deeper folds
- sudden jawline loss
In transgender clients:
MTF (oestrogen therapy) →
- testosterone falls
- skin becomes more feminine, thinner, sensitive
FTM (testosterone therapy) →
- oil increases
- acne and inflammation may increase
- increased collagen density over time
DHT (DIHYDROTESTOSTERONE) — THE JAWLINE BREAKOUT HORMONE
DHT is a derivative of testosterone and drives:
- jawline acne
- cystic breakouts
- inflammation
- scarring
- oil overproduction
High DHT is common in:
- men
- women with hormonal imbalance
- PCOS
- FTM testosterone therapy
- stress-driven androgen surges
It also causes:
- deeper pores
- thicker texture
- stronger sebaceous glands
- more stubborn inflammation
CORTISOL — THE STRESS HORMONE THAT ACCELERATES AGEING
Cortisol is one of the most destructive hormones for the skin.
It causes:
- collagen breakdown
- inflammation
- redness
- sensitivity
- dehydration
- slower healing
- barrier disruption
- pigmentation
- increased vasodilation
- worsening rosacea patterns
- tired, flat skin
Long-term cortisol elevation
inflammageing + structural ageing + faster visible ageing
THYROID HORMONES — THE SKIN’S METABOLIC REGULATORS
Thyroid hormones (T3/T4) control:
- cell turnover
- hydration
- microcirculation
- barrier function
- oil balance
Low thyroid (underactive):
- dry skin
- coarse texture
- slow healing
- puffiness
- increased inflammation
- dullness
- poor circulation
High thyroid (overactive):
- flushing
- thinning skin
- redness
- sensitivity
- accelerated ageing
INSULIN — THE SUGAR-INFLAMMATION HORMONE
High insulin levels:
- increase inflammation
- increase breakouts
- drive pigmentation
- contribute to PIH
- worsen redness
- accelerate collagen glycation (stiff, dull collagen fibers)
Glycation is a major cause of:
- yellow undertones
- reduced firmness
- quicker ageing
This is seen across all genders and ethnicities.
GROWTH HORMONE (GH) — THE REPAIR & REGENERATION HORMONE
GH supports:
- collagen synthesis
- wound healing
- cell turnover
- structural rebuilding
GH declines from age 25 onward — reducing healing speed and collagen density.
PROLACTIN — A HIDDEN PIGMENT + INFLAMMATION HORMONE
High prolactin (stress, breastfeeding, medications) can cause:
- pigmentation
- uneven tone
- inflammation
- dullness
- jawline breakouts
It is under-recognised but significant.
PERIMENOPAUSE — THE CHAOTIC HORMONE PHASE
Perimenopause causes:
- fluctuating oestrogen
- declining progesterone
- increasing inflammation
- increased sensitivity
- unexpected breakouts
- redness
- inconsistent collagen production
- accelerated structural ageing
Clients often describe:
“I don’t recognise my skin anymore.”
Fully rooted in hormonal fluctuation.
MENOPAUSE — THE COLLAGEN CRASH
At menopause:
- oestrogen drops sharply
- collagen drops rapidly
- elastin declines
- fat pads shift
- ligaments weaken
- SMAS loosens
- dermis thins
- sensitivity rises
- pigment increases
This is the second-biggest change in female ageing after puberty.
ANDROPAUSE — MALE HORMONAL AGEING
Gradual testosterone decline causes:
- structural heaviness
- jawline sagging
- deeper folds
- thickened lower face ageing
- oil reduction
- dry surface texture
Men age later — but faster when decline begins.
TRANSGENDER HORMONE THERAPY — UNIQUE HORMONAL AGEING PATTERNS
MTF (male-to-female):
- increased sensitivity
- reduced thickness
- reduced oil
- increased pigment risk
- more feminine ageing patterns
- under-eye ageing increases
- better barrier function
FTM (female-to-male):
- increased oil
- increased inflammation
- higher acne risk
- stronger collagen network
- slower wrinkle development
Aeternitas must tailor settings accordingly.
The Art of Scientific Aesthetics
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