One of the most common complaints I hear from my female patients over 40 is that they're losing more hair than they used to—even if they haven't changed a thing. Sometimes it's the growing collection of hair wrapped around the shower drain. Sometimes it's the increasingly crowded hairbrush. Other times it's a ponytail that seems noticeably thinner than it once was.
The truth is that some degree of hair shedding is completely normal. Most people lose dozens of hairs every day as part of the natural hair growth cycle. But if you're noticing more hair than usual in your brush, your drain, or on your bathroom floor, it may be time to explore whether something else is contributing to the problem.
The Hair Growth Cycle
To understand why hair loss occurs, it helps to understand how hair grows.
Each hair follicle moves through a cycle of growth, rest, and shedding. At any given time, most of your hair is actively growing, while a smaller percentage is resting or preparing to shed. In fact, most women lose somewhere between 50 and 100 hairs per day as part of the natural hair growth cycle
Problems arise when too many follicles enter the shedding phase at the same time or when new hair growth slows down. When this happens, hair may become noticeably thinner over time. In many cases, the trigger occurred several months earlier.
Common Culprits
Here are some of the most common causes of excessive hair loss in women over 40:
- Menopause: Estrogen helps support healthy hair growth. As estrogen levels begin to decline during perimenopause and menopause, many women notice changes in both hair quality and hair density. At the same time, the relative influence of androgens (male hormones that women naturally produce in smaller amounts) may become more noticeable. In genetically susceptible women, this can contribute to gradual thinning along the crown or widening of the hair part.
- Iron deficiency: One of the most commonly missed contributors to hair loss is low iron stores. Many women assume that if they aren't anemic, their iron levels must be adequate. Unfortunately, that's not always true. This is where ferritin becomes important. Ferritin reflects the amount of stored iron available in your body. Hair follicles are surprisingly sensitive to low iron stores and may begin shedding long before anemia develops.
- Thyroid issues: Hair follicles are highly responsive to thyroid hormones. Both hypothyroidism and hyperthyroidism can contribute to hair loss. In some cases, thinning hair may be one of the earliest symptoms. Fatigue, weight changes, constipation, cold intolerance, and dry skin are other common symptoms.
- Rapid weight loss: Whether weight loss occurs through dieting, illness, surgery, or medications such as GLP-1 agonists, significant weight reduction can place stress on the body. Hair growth is not essential for survival. When your body senses a calorie deficit or nutritional stress, it may redirect resources away from the hair follicles and toward more critical functions.
- Inadequate protein intake: Hair is primarily made of protein, so consistently inadequate protein intake can contribute to poor hair growth and increased shedding. If your diet consists primarily of salads, snack foods, and small portions of protein, your hair follicles may eventually take notice.
- Chronic stress: Physical and emotional stress can push more hair follicles into the shedding phase. The result is a condition known as telogen effluvium, one of the most common causes of diffuse hair loss in women.
- Medications: A variety of prescription medications have been associated with increased hair shedding, including certain blood pressure medications, antidepressants, blood thinners, acne medications, thyroid medications, seizure medications, and some autoimmune disease treatments. Weight-loss medications may also contribute indirectly.
- Supplements: While nutrient deficiencies can contribute to hair loss, taking too much of certain supplements can create problems as well. Excess vitamin A and selenium are among the most well-known causes of supplement-related hair shedding, while high doses of zinc or iodine may contribute indirectly by disrupting nutrient balance or thyroid function.
What About Hair Growth Supplements?
The hair-loss industry is a multibillion-dollar business. Every day, women are bombarded with advertisements for hair gummies, collagen powders, shampoos, serums, vitamins, laser devices, and miracle cures that promise thicker, fuller hair. But no supplement can fully compensate for an untreated root cause.
That said, hair growth is a slow process, and many women want to provide additional support while they work with their healthcare provider to investigate and address potential contributors. Several nutrients play important roles in healthy hair growth, including protein, iron, zinc, selenium, biotin, vitamin D, and certain B vitamins. Collagen supplements may also help some women increase their overall protein intake, though collagen alone is unlikely to solve significant hair loss.
Some hair-support formulas combine many of these nutrients into a single product and may be worth considering, particularly for women whose diets are lacking in key nutrients or who are experiencing age-related changes in hair quality and thickness.
The most important thing to remember is that supplements generally work best when they're supporting a healthy foundation—not replacing one.
The Bottom Line
If you're experiencing more hair loss than usual, speak with your healthcare provider so underlying medical causes can be ruled out first.
While some degree of hair shedding is completely normal, significant or persistent hair loss deserves attention. The sooner the underlying cause is identified, the sooner you can take steps to support healthier hair growth and potentially prevent further thinning.