Article · Causes of Hair Loss
What Causes Hair Loss in Women? What a 2025 Dermatology Review Found
The short answer
If your hair is thinning, you're in good company, and there may be more than one reason behind it. A 2025 review by a team of dermatologists points to five root causes: hormones, inflammation, low nutrients, aging and oxidative stress. The authors say looking at these root causes can help explain why hair thins. Hair loss is common. The review notes that more than half of postmenopausal women and up to 40% of otherwise healthy women suffer from hair loss. According to the review, female pattern hair loss is the most common type. Others include shedding (telogen effluvium), alopecia areata and scarring types. The authors note that too little of some nutrients can contribute to hair loss, and so can too much. The review also notes that high doses of biotin may interfere with some lab tests.
Why is my hair thinning?
If your part looks wider or your ponytail feels thinner, here's what may be going on. The authors of a 2025 review in the Journal of Drugs in Dermatology grouped the causes into five broad categories:
Hormones. DHT, a potent androgen, may shrink hair follicles, especially in people who are genetically predisposed, according to the review. PCOS, thyroid conditions, menopause and hormone shifts after pregnancy can all play a part, the authors write.
Inflammation. Autoimmune, connective tissue and metabolic conditions can show up as hair loss, and inflammation has been found in the scalp in pattern hair loss, the review notes.
Nutrient gaps. Low levels of some vitamins and minerals are linked to hair loss, according to the review.
Aging. Hair can become thinner, drier and more brittle over time, and sun exposure, chemical treatments and pollution can contribute, the authors write.
Oxidative stress. Oxidative stress has been linked to several types of hair loss and may disrupt the normal hair growth cycle, according to the review.
Which nutrients matter most?
In the review, low iron stands out as a well-recognized cause of shedding (telogen effluvium), and low vitamin D is linked mainly to alopecia areata. The authors note that low levels of zinc, copper, selenium and some B vitamins have also been linked to hair loss. But more isn't always better: the authors report that too much vitamin A or selenium may also contribute to hair loss.
The review also notes that high doses of biotin may interfere with some lab tests.
What this means for you
The authors note that many supplements contain more than the recommended daily amounts, and they warn this may cause toxicity or other side effects.
Beyond the Study: a board-certified dermatologist can help sort out which causes apply to you, check supplement labels so you don't double up on nutrients, and it's smart to tell your clinician about any biotin before blood work.
FAQs
Which vitamin deficiency causes hair loss? The review points to low iron as a well-recognized cause of shedding. In the review, low vitamin D, zinc, copper and selenium are also linked to hair loss.
For the full findings and methods, read the full publication: Addressing the Root Causes of Female Hair Loss and Non-Pharmaceutical Interventions.
Read the full publication → Leavitt A, Hawkins SD, Kindred C, Frey C, Gainers M, Grekin SK, Leavitt M. Addressing the Root Causes of Female Hair Loss and Non-Pharmaceutical Interventions. J Drugs Dermatol. 2025;24(7):658–661.
Free full text: July 2025 issue PDF (article on PDF pages 14–17)
Disclosure: Co-author Dr. Chesahna Kindred is a founding advisor to Xtressé. Dr. Adam Leavitt, the corresponding author, is an investor in Xtressé and may financially benefit from its success. Other author disclosures are listed in the publication.
This article is for education only and is not medical advice. Talk with your healthcare provider about your own hair and scalp health.
Key takeaways
- DHT, a potent androgen, may shrink hair follicles, especially in people who are genetically predisposed.
- Low iron stands out as a well-recognized cause of shedding (telogen effluvium), and low vitamin D is linked mainly to alopecia areata.
- Oxidative stress has been linked to several types of hair loss and may disrupt the normal hair growth cycle.
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