THE ENDOCRINE PERSPECTIVE
Losing more hair? Start with the cause, not a supplement.
More hair in the shower drain. A wider part. A ponytail that feels thinner than it used to. If this is happening to you, it can be upsetting, and you're far from alone. Hair is tied to how we see ourselves, so worrying about it is completely normal.
By Dr. Christine Cox, DO, Endocrinologist
2 min read
September 28, 2026
The good news: hair loss is a symptom, not a diagnosis, and it often has a cause we can find and treat. So before reaching for another supplement, the kinder first question is: what is your body trying to tell you?
Four common causes
Many women have one of these, and sometimes more than one at once. None of them is your fault.
Your thyroid
An underactive or overactive thyroid can both slow hair growth. Hair loss alone doesn't mean you have thyroid disease, though.
Test if you also notice: fatigue, weight change, feeling too hot or cold, a racing or slow heart, bowel changes, or cycle changes.
Nutrition & weight loss
Hair follicles are some of the busiest cells in your body. They need protein, iron, and zinc to keep growing.
Watch for: rapid weight loss, illness, surgery, childbirth, or major stress. These can trigger telogen effluvium, an all-over shed that often shows up months later.
GLP-1 medications
Shedding on semaglutide or tirzepatide is common, and the research is still evolving. Fast weight loss, eating less, and nutrient gaps likely play a big role, so the medication may not be the whole story.
Perimenopause & hormones
Shifting hormones can overlap with female pattern hair loss. Androgens (like testosterone) become a bigger suspect when thinning comes with new acne, more facial hair, or irregular cycles.
Female pattern hair loss can also happen with normal testosterone levels.
What about biotin?
It's tempting, but it's usually not the answer. Biotin helps very little unless you're truly deficient. It can also skew thyroid blood tests, making TSH look falsely low and T4/T3 falsely high. Many "hair, skin & nails" blends contain high doses.
LAB TIP Stop biotin 3 days before thyroid bloodwork to avoid a misleading result.
So what actually works?
The right treatment depends on the cause, and many types of shedding improve once it's addressed.
If your hair loss is sudden, patchy, painful, inflamed, or scarring, please see a dermatologist promptly.
HOW VITAL COEUR CAN HELP
You don't have to figure this out alone. We'll help you find the cause, then treat it.
- Listen. A physician visit to hear your full story: when the shedding started, your cycle, medications, diet, and stress.
- Investigate. Targeted lab work, chosen for your symptoms, to check thyroid, hormones, and nutrient levels.
- Treat. A personal plan that fixes the cause, with medical treatment, nutrition support, and follow-up as your hair recovers.
Dr. Christine Cox, DO is an endocrinologist and the Co-founder and Medical Director of Vital Coeur Health.
Hair loss in women, Thyroid hair loss, Perimenopause hair loss, GLP-1 hair loss, Telogen effluvium, Biotin, Female pattern hair loss
Sources: American Academy of Dermatology; American Thyroid Association; FDA biotin safety communications; Herskovitz & Tosti, Int J Womens Dermatol, 2018; Almohanna et al., Dermatol Ther, 2019; van Zuuren et al., Cochrane Database Syst Rev, 2016. Evidence on GLP-1 medications and hair loss is still evolving.
For educational purposes only. This is not medical advice; individual evaluation and treatment may differ.