"My hair is falling out in clumps — what's causing it?"

Why hair falls out in clumps — and why the timing is almost always confusing

Your hair follicles cycle through three phases: growth (anagen), transition (catagen), and rest (telogen). Under normal conditions, only about 10–15% of your follicles are in the resting phase at any given time, and those hairs shed gradually so you never notice. When something disrupts this cycle — illness, a hormonal shift, a nutritional crash, extreme stress — a much larger proportion of follicles get knocked into the resting phase all at once. Two to four months later, they all shed together. This is called telogen effluvium, and it's the most common reason hair comes out in clumps rather than gradually.

The delay between cause and shedding is what makes this so disorienting. You get COVID in October and your hair starts coming out in handfuls in January. You have a baby in spring and by late summer your shower drain is clogged. The triggering event feels distant, so it's easy to chase the wrong explanation. Other causes — thyroid dysfunction, iron deficiency anaemia, scalp conditions like alopecia areata, or the long-term hormonal pattern of androgenetic alopecia — produce a similar picture but have different mechanisms and different solutions.

One important distinction: if you're seeing clumps pulling from one patch rather than distributed shedding across the scalp, that points more specifically toward alopecia areata — an autoimmune condition where the immune system mistakenly attacks hair follicles. It's more common than most people know, affecting roughly 2% of the population at some point in their life, and it responds to treatment. The distinction matters because the solutions are not the same.

Clump shedding isn't one single problem — the pattern tells you a lot

The same symptom — hair coming out in large amounts — can have very different root causes depending on when it started, where it's happening, and what else is going on in your life or body.

What happens if you wait it out without finding the cause

Some hair loss genuinely does resolve on its own — postpartum telogen effluvium, for example, typically peaks around four months after birth and then reverses without any intervention. But waiting without understanding the cause is a gamble, because the conditions that require treatment — thyroid disease, iron deficiency, alopecia areata, scalp inflammation — don't get better on their own, and some become harder to treat the longer they go unchecked. Follicles that have been inactive for an extended period can scar, and scarred follicles don't regrow hair. The window for effective treatment is real.