Anagen Effluvium: Causes, Triggers, and What You Can Do

When your hair starts falling out in clumps—not from brushing, not from stress, but suddenly and sharply—it’s often anagen effluvium, a type of hair loss that happens during the active growth phase of the hair cycle, usually triggered by chemotherapy, radiation, or certain medications. Also known as toxic alopecia, it’s not the same as the gradual thinning you see with aging or genetics. This is hair falling out while it’s still growing, and it can be shocking. Unlike telogen effluvium, where hair sheds after resting, anagen effluvium attacks follicles right in the middle of their job, leading to rapid, widespread loss—sometimes within days of starting a new drug.

Most cases are tied to chemotherapy, a common cancer treatment that targets fast-dividing cells, including hair follicles. Drugs like doxorubicin, cyclophosphamide, and paclitaxel are notorious for this side effect. But it’s not just cancer meds—anticoagulants, gout medications like colchicine, and even high-dose vitamin A can trigger it too. You’ll notice hair thinning across your scalp, eyebrows, and even body hair. It’s not permanent, but it happens fast, and that’s what makes it so unsettling. The good news? Once you stop the trigger, hair usually grows back within 3 to 6 months. Your follicles aren’t dead—they’re just stunned. Some people even get their full head back before finishing treatment.

What you won’t find in most guides is how scalp cooling, a technique where chilled caps are worn during chemo infusions to reduce blood flow to hair follicles. Also called cold caps, this method has helped many patients keep most of their hair during treatment. It’s not perfect, and it doesn’t work for every drug or every person, but it’s one of the few proven ways to reduce anagen effluvium without stopping the therapy you need. Other approaches—like minoxidil or supplements—don’t stop the damage, but they might help regrowth after the fact. What matters most is knowing what caused it. If you’re on a new medication and your hair is falling out faster than ever, it’s not just stress or bad shampoo. It’s likely anagen effluvium, and you’re not alone.

Below, you’ll find real-world posts that dig into the medications that cause this kind of hair loss, how to tell it apart from other types, and what steps people have actually taken to manage it. Some focus on chemotherapy side effects, others on drug interactions that surprise even doctors. You’ll see what works, what doesn’t, and what to ask your pharmacist before starting a new prescription. This isn’t guesswork—it’s what people have lived through, and what you can use to protect yourself.