Anagen Effluvium
Anagen effluvium is sudden hair loss caused by an insult severe enough to halt cell division in actively growing follicles, so the shaft breaks rather than shedding normally. It appears within days to weeks, most often after chemotherapy or radiotherapy, and is usually reversible.
Anagen effluvium hits the hair while it is still growing. An insult severe enough to stop cell division in the bulb interrupts the shaft mid-production. The hair does not complete its cycle and release normally — it fractures at the weakened point and breaks off, often within days to a few weeks of the cause.
| Anagen effluvium | Telogen effluvium | |
|---|---|---|
| Phase affected | Growing hairs | Hairs pushed into rest |
| Timing | Days to a few weeks | Around three months later |
| How the hair comes out | Breaks; no club root | Sheds with a club-shaped root |
| Extent | Can be near-total | Diffuse thinning |
The root tells the two apart. A hair shed at the end of telogen carries a small white club at its base. A hair lost in anagen effluvium has no such club — it is a broken shaft. That single detail, visible on a hair held up to the light, separates a slow diffuse shed from an acute one.
Because the follicle is stunned rather than destroyed, it usually recovers. Regrowth follows once the cause is removed, though the returning hair can differ in texture or colour for a period.
The most common causes are systemic and identifiable — chemotherapy and radiotherapy above all, and less often severe toxic exposure. It is not a pattern process and is not treated with surgery.
Related terms
For pattern loss, which behaves nothing like this, see the Norwood scale. For whether surgery is appropriate at all, see should I get a hair transplant.
