thinning hair causes

Photo: Ian Hooton/Getty Images

4 of 4

NEXT

SLIDESHOW

You're Noticing: You're Losing Hair in Patches

Potential cause: Skin conditions like eczema or psoriasis
Why it leads to thinning: Scaliness and buildup of skin cells on the scalp can lead to hair loss, explains Shah. (Scratching to relieve itching can make it worse.) Seborrheic dermatitis, an inflammatory condition that mainly affects the scalp and causes scaly patches, red skin and dandruff, can also trigger hair loss.
How to fix it: Treat the skin issue and hair should start to grow back on its own. Topical steroids, antifungals and medicated shampoos are often the first steps, and your dermatologist may recommend stronger options like phototherapy or oral and injectable medications if you need a more aggressive treatment.

Potential cause: Alopecia areata
Why it leads to thinning: This autoimmune condition is relatively rare, affecting roughly 2 percent of the U.S. population, but it's very noticeable because it starts with quarter-sized patches of hair loss. It often begins in childhood as the immune system attacks hair follicles.
How to fix it: There's no cure or official medications, but your doctor might recommend treatments approved for other hair-loss conditions to try to stimulate growth (cortisone injections are one option, says Day). Your dermatologist will confirm the condition first (often by pulling out a hair or two and examining them under a microscope or doing a skin biopsy of the scalp) and proceed from there.