Telogen vs. Anagen Effluvium — The Two Big Sudden Shed Patterns
One is reversible, one is rare and dangerous. The difference matters for your timeline, your bloodwork, and whether to operate.
Two Mechanisms, Very Different Stakes
Both telogen effluvium and anagen effluvium look the same to a panicking patient: a sudden surge in hair shedding, often visible in the shower drain, on the pillow, or in the brush. The mechanism behind each — and the appropriate response — is completely different.
Telogen Effluvium — The Stress Trigger
In healthy adults, around 10–15% of follicles are in the resting (telogen) phase at any time. A major stressor — illness, surgery, severe diet, childbirth, divorce — pushes a much larger fraction into telogen at once. About 2–4 months later, all those follicles shed together.
Telogen effluvium is almost always reversible. Once the trigger passes, follicles re-enter the growing phase. Recovery takes 6–12 months.
Anagen Effluvium — Direct Toxicity
Anagen effluvium is shedding from follicles still in the growing (anagen) phase. The follicle has been directly damaged — most commonly by chemotherapy, radiation, or severe heavy-metal toxicity. Onset is rapid (within weeks), shedding is dramatic, and the cause is usually obvious.
Recovery depends on the cause. Post-chemo regrowth typically begins 3–6 months after treatment ends and reaches 80% of normal within a year.
Which One Are You Looking At?
Three quick signals separate the two:
- Onset speed: telogen is delayed (months after the trigger); anagen is immediate (weeks)
- Hair characteristics: telogen sheds full-length hairs with white club roots; anagen sheds tapered, broken, dystrophic shafts
- Trigger profile: telogen comes after life stress, illness, or hormonal change; anagen almost always has a chemical or radiation cause
When to Get Bloodwork
For any unexplained shedding lasting more than 8 weeks, get tested: ferritin, full thyroid panel, vitamin D, B12, zinc. Many telogen effluviums are partly nutritional and resolve faster once the underlying deficiency is corrected.