Hair Shedding Or Thinning? How To Tell What's Happening To Your Hair
More hair in the brush than usual is unsettling, and the first instinct is to buy something. Before you do, it helps to know which of two very different problems you are probably dealing with, because they don't call for the same answer.
Some Shedding Is Normal
The American Academy of Dermatology (AAD) says it is normal to shed somewhere between 50 and 100 hairs a day. Hair grows in cycles, and every hair eventually rests and falls out so a new one can take its place. The real question is whether more is falling out than usual, or less is growing back.
Sudden Shedding: Telogen Effluvium
When a lot of hair comes out at once, all over the scalp, the usual cause is telogen effluvium. A shock to the body pushes many hairs into the resting phase at the same time, and they fall out together a few months later. The AAD lists triggers such as giving birth, a high fever or illness, surgery, major stress, stopping birth control pills, and losing a lot of weight. Because of that delay, the connection is easy to miss. Once the trigger has passed, the AAD says hair usually regains its normal fullness within six to nine months.
This matters if you are taking a GLP-1. Fast weight loss is a known trigger, and the FDA labels for Wegovy and Zepbound list hair loss among the side effects reported more often than with placebo. Our guide to GLP-1 side effects covers what else to expect.
Gradual Thinning: Female Pattern Hair Loss
Female pattern hair loss happens slowly, over years. The AAD describes it as usually starting with a widening part, then thinning across the top and crown, while the front hairline tends to stay where it was. It tends to run in families. Unlike telogen effluvium, it doesn't settle on its own, and the AAD notes that treatment tends to work better when it starts earlier.
What Labs Can Rule Out
Thinning can also come from things a blood test can find. The AAD lists thyroid disease and iron deficiency among the medical causes of hair loss, along with polycystic ovary syndrome, which can show up as irregular periods, acne, or extra facial hair. Our guides to ferritin and iron tests and thyroid tests for women explain what those results mean. Test first rather than starting iron or thyroid treatment on a guess.
Where Minoxidil Fits, And When To See A Dermatologist
Telogen effluvium usually doesn't need a prescription. It needs time, and dealing with the trigger where you can. For female pattern hair loss, topical minoxidil is the treatment FDA-approved for women. As a tablet, minoxidil is FDA-approved only for high blood pressure, so the low-dose oral minoxidil Urania offers is an off-label use for hair; our guide to oral minoxidil for women covers its side effects and who should avoid it. See a dermatologist in person if you notice round bald patches, or redness, scaling, pain, or burning on your scalp, because those point to conditions minoxidil isn't meant for.
Where To Start
If the shedding began a few months after a clear trigger, give it time and keep an eye on it. If the thinning has been slow and steady, or you can't tell which it is, start with labs and an intake. A licensed provider reviews your history, including pregnancy plans, heart conditions, and current medications, and decides whether a treatment fits you.
This guide explains general information and is not medical advice. It doesn't replace a licensed provider reviewing your own history.