Currently accepting new patients
ISHRSABHRSFISHRS
EducationThe BiologyThree Cycles of Hair Growth

Anagen. Catagen. Telogen.

Your hair doesn’t grow continuously. It cycles through three distinct phases — active growth, brief transition, then rest — and shedding 50 to 100 hairs a day is the system working as designed. Understanding the cycle explains the ‘shed’ phase of post-op recovery, why finasteride takes months to show effect, and why patience matters.

Reviewed by Dr. Robert Jones
The biology, plainly
CHAPTER IThe Cycle

Three phases. Asynchronous.

Each individual follicle on your scalp cycles through anagen, catagen, and telogen on its own clock — not synchronised with neighbours. At any given moment, the great majority of your follicles are growing, a small fraction are transitioning, and a modest fraction are resting. The asynchronous nature of the cycle is what gives you a continuous head of hair: you’re always shedding old hairs and growing new ones, but never all at once.

When a triggering event (illness, stress, postpartum hormonal shift) pushes a higher-than-normal percentage of follicles into telogen simultaneously, the synchronisation produces a sudden visible shed three months later — that’s telogen effluvium. Normally, the cycle stays asynchronous and shedding stays invisible.

CHAPTER IIThe Three Phases

In detail.

Phase 1 · 2–7 years

Anagen

The active growth phase. The follicle produces a new hair shaft continuously, growing it from the root upward at roughly 1cm per month. About 85–90% of your hair is in anagen at any given time. Genetic factors determine how long anagen lasts for each follicle — and therefore how long your hair can grow before it cycles out.

Phase 2 · 2–3 weeks

Catagen

The transition phase. The follicle stops producing hair, the bulb detaches from the blood supply, and the follicle prepares to enter rest. About 1% of your hair is in catagen at any given time. Brief, biologically critical, mostly invisible.

Phase 3 · ~3 months

Telogen

The resting phase. The follicle is dormant, the existing hair shaft is held in place but no new growth is happening. About 10–15% of your hair is in telogen at any given time. At the end of telogen, the existing hair is shed (often when a new anagen-phase hair pushes it out from below) and the cycle begins again.

CHAPTER IIIWhy It Matters

For surgery. And for medication.

The post-op “shed.” When transplanted follicles are moved to the recipient site, the surgical trauma pushes them into telogen synchronously. Three weeks later, the transplanted hairs shed all at once — patients see hair they paid for falling out and panic. The follicle is alive. It’s entering a dormant phase before the new anagen cycle begins. New growth emerges around month four. Trust the cycle.

Why medication takes months. Finasteride and minoxidil don’t produce visible change immediately. They modify the cycle: prolonging anagen, shortening telogen, gradually thickening miniaturised follicles. Because each follicle is on its own clock, the cumulative effect appears over 3–6 months as more follicles cycle through under the new hormonal/vascular environment.

Why “more shedding” on minoxidil is temporary. Some patients see increased shedding in the first weeks of minoxidil. That’s the medication pushing dormant telogen follicles out so they can begin a new anagen cycle. Counter-intuitive but normal.

The biology is on your side

Hair growth and recovery are slower than most patients expect. The result you see at month four isn’t the result — it’s month four. Trust the cycle.

Send Your Photos DHT explained