Hair Loss in Women: The Causes Worth Checking

Hair loss in women almost always follows one of two patterns. Telling them apart matters more than any product you might buy. In the first, hair sheds from all over the scalp. This comes a few months after some shock to the body, and it usually recovers. In the second, the parting slowly widens while the hairline stays put. That is female pattern hair loss, and it behaves as a long-term condition.

The two common patterns#

Telogen effluvium is the sudden kind. A physical or emotional stress pushes an unusually large share of hair follicles into their resting phase at once. About two to three months later they all let go together. The usual triggers are childbirth, a high fever, surgery, a severe infection, rapid weight loss and spells of intense stress. The delay is why people so often blame the wrong month.

Female pattern hair loss is the slow kind. Follicles gradually make finer, shorter hairs, most visibly along the central parting. Genes have a strong say in it. It also becomes more common with age, above all around and after menopause. It does not usually cause bald patches.

What is really worth testing#

A small set of tests answers most of the treatable questions:

• a full blood count
• ferritin, which measures iron stores
• thyroid function

Low iron stores and thyroid disorders are both common in women. Both cause hair thinning, and both are easy to treat. Are there also irregular periods, acne or unwanted hair growth? Then a doctor may look at hormones linked to polycystic ovary syndrome.

What helps, and what does not#

Treating a real deficiency helps. Iron replacement helps when iron stores are really low. Thyroid treatment helps when the thyroid is really underactive. Both improve hair over months, not weeks, because follicles work slowly. Taking iron without a deficiency does not thicken hair, and it can cause harm over time. There are licensed medical treatments for female pattern hair loss. They are worth discussing with a doctor rather than ordering blind. Suitability depends on your history, and on whether pregnancy is possible.

Gentle handling is underrated: less tension from tight styles, less heat, less bleaching. Traction alopecia comes from years of tight braids or ponytails. It is one of the few kinds of hair loss that can become permanent, and it is entirely preventable.

Most supplements sold for hair have thin evidence in people who are not deficient. Biotin is the clearest example. Biotin deficiency is rare, and high-dose biotin can distort several common lab tests, including thyroid and cardiac blood tests. That sometimes leads to real confusion over a diagnosis.

When to be seen sooner#

Smooth, coin-shaped bald patches suggest alopecia areata, an autoimmune condition. Redness, scaling, burning or a shiny scarred scalp suggests an inflammatory scarring condition. There, early treatment protects the follicles that remain. Rapid hair loss with new facial hair, acne or a deepening voice needs prompt hormonal assessment.

Where to take this next#

Iron is the single most common correctable cause in women who are still having periods. The fuller guide to iron deficiency anemia explains what the numbers on your blood test mean. It also explains why ferritin often tells the story before hemoglobin does.