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Everyone loses hair—we actually lose up to 100 strands each day. But you may be noticing that you’re losing an unusual amount of hair.
We spoke with Michele Green, MD, a board-certified dermatologist in New York City, to ask her, “why is my hair falling out?” The answer? There is a wide range of things that lead to hair loss, from genes and hormones, to medical conditions, medications, and even stress. Fortunately, according to Dr. Green, “There’s a whole host of things that people can do, especially men, to grow back their hair.”
Read on to learn what causes hair loss and what you can do about it.
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What is hair loss?
You’ve probably noticed that hair shedding happens all the time—you find hairs on the floor, in your shower, in your brush. But how do you know if your hair loss is normal or excessive shedding?
Let’s look at the normal hair growth cycle.
Your hair grows from hair follicles, which are specialized structures in your skin. Most of the time, approximately 90% of your hair shafts are in the active growing stage (called the anagen phase)—and they stay in this phase for 2–6 years. Then there is a transition (catagen) phase for 1–2 weeks, and finally, the hairs enter the resting (telogen) phase for 2–4 months. After the resting period, the hairs fall out, and the cycle starts again with new hair growth. You should expect to lose 50–100 strands per day during a normal hair growth cycle (Murphrey, 2020).
If you notice a receding hairline, thinner hair than usual, or bald patches, you may have alopecia (excessive hair loss). It’s a good idea to get checked out by a dermatologist if you notice a worrisome amount of hair loss since, as Dr. Green says, there could be a medical cause.
What causes hair loss?
As Dr. Green stated, there are several reasons your hair may be thinning. Let’s take a look at some of the possible culprits.
The most common cause of hair loss is androgenetic alopecia (also called androgenic alopecia) (Al Aboud, 2020). Better known as male pattern baldness or female pattern hair loss, this type of hair loss is hereditary. That means, if you have it, you likely have at least one family member who also has this type of hair loss.
While both men and women can suffer from hair loss, the pattern of hair thinning is often different. In typical male pattern baldness, the hair becomes thinner on the tops of the head, the side of the scalp, or you see a receding hairline. Women tend to get hair loss throughout their hair or a widening part. Approximately 50% of men over 50 experience androgenetic alopecia, while almost 40% of women develop female pattern hair loss after menopause (Phillips, 2017).
Alopecia areata, another cause of hair loss, is an autoimmune disease. Your immune system attacks the hair follicles, leading to inflammation and baldness—this can be patchy, involve your entire scalp, or affect all of the hair on your body (Lepe, 2020).
Thyroid disease can also lead to hair loss. Having an overactive thyroid (hyperthyroidism) or an underactive thyroid (hypothyroidism) can both lead to hair loss. Working with your healthcare provider to treat your thyroid condition can help to slow this process and allow normal hair growth once again.
Stress, pregnancy, and medications
If you have a high fever or are very ill, postpartum, taking certain medications, or feeling excessive stress levels, you may experience hair loss as a result of these conditions or medications disrupting the normal hair growth cycle. This type of hair loss is called telogen effluvium.
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Medications associated with this type of hair loss include those used to treat thyroid conditions, high blood pressure, and more. Stopping birth control pills can also trigger hair shedding. Fortunately, once you get better or stop the medication, your hair usually grows back (Phillips, 2017).
Certain inflammatory conditions, like folliculitis (infection of the hair follicle) or chronic scratching due to psoriasis, can kill hair follicles and replace them with scar tissue, leading to scarring or a condition called cicatricial alopecia. Ringworm (a fungal infection of the scalp) and trichotillomania (an impulse disorder where you can’t stop pulling your hair) can also lead to hair loss.
Lastly, wearing tight hairstyles that constantly pull on the scalp, like tight braids or ponytails, can damage the hair follicles and lead to bald spots. When this occurs, it’s called traction alopecia (Billero, 2018).
Hair loss treatments
Your hair loss treatment options will depend on the cause of your hair loss. According to Dr. Green, “If it’s a typical case of male pattern baldness, there are a few options. You can take a medication called Propecia (generic name finasteride; see Important Safety Information), a pill that helps men grow back their hair. You can try the topical treatment Rogaine (minoxidil), which you apply every night or twice a day to the scalp.”
Dr. Green also describes a procedure called PRP, or platelet-rich plasma. “PRP is injections of your own blood into the scalp—that’s really effective. We take blood—just like a regular blood test—and spin it to separate the platelets. Those platelets have wound healing and growth factors, and we inject them into the scalp. It takes at least four treatments. I’ve had patients just grow back their hair—it’s pretty remarkable.”
Other treatments include a laser cap, which operates on the theory that the light from the cap reduces inflammation and helps hair regrow.
However, to find the most effective remedy for hair loss, Dr. Green finds that the solution is not usually just one treatment—it’s often a combination. Some people with mild hair loss do well on minoxidil, while others need oral finasteride. She may use medications in combination with the laser cap or PRP (Donovan, 2021).
If those treatments don’t work, hair transplantation is another option. Alternatively, camouflage options include wigs, hairpieces, scarves, shaving, etc.
As Dr. Green suggested, seek medical advice from your provider to discuss hair loss treatment options or any questions you may have about your thinning hair.
How to prevent hair loss
Everyone wants to prevent hair loss. Unfortunately, you can’t do much about some of the causes of hair thinning (like genetics).
Medications that cause hair loss: what you need to know
Some causes are preventable, though. Maintaining healthy hair care and styling habits can help prevent hair loss—avoid using high heat on your hair, like curling irons, flat irons, or high heat hair dryers. Likewise, don’t use hair products that contain harsh chemicals or bleach. High heat and chemicals can both damage your hair follicles, making it more likely that you’ll experience hair loss (Bloch, 2019).
Some people attribute iron deficiency anemia and low levels of other nutrients as potential causes of hair loss. However, clinical trials have not demonstrated definitive evidence that taking vitamins or other supplements prevents hair loss or promotes regrowth (Almohana, 2019).
Lastly, ignore the myth that healthy hair needs 100 brushstrokes a day—over-brushing your hair will increase your chances of excessive shedding.
- Al Aboud, A. M. & Zito, P. M. (2020). Alopecia. [Updated Aug. 11, 2021]. In: StatPearls [Internet]. Retrieved on Dec. 3, 2021 from https://www.ncbi.nlm.nih.gov/books/NBK538178/
- Almohanna, H. M., Ahmed, A. A., Tsatalis, J. P., & Tosti, A. (2019). The role of vitamins and minerals in hair loss: a review. Dermatology and Therapy, 9(1), 51–70. doi: 10.1007/s13555-018-0278-6. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30547302/.
- Billero, V. & Miteva, M. (2018). Traction alopecia: the root of the problem. Clinical, Cosmetic and Investigational Dermatology, 11, 149–159. doi: 10.2147/ccid.s137296. Retrieved from https://pubmed.ncbi.nlm.nih.gov/29670386/
- Bloch, L. D., Goshiyama, A. M., Dario, M. F., Escudeiro, C. C., Sarruf, F. D., Velasco, M., et al. (2019). Chemical and physical treatments damage Caucasian and Afro-ethnic hair fibre: analytical and image assays. Journal of the European Academy of Dermatology and Venereology: JEADV, 33(11), 2158–2167. doi: 10.1111/jdv.15761. Retrieved from https://pubmed.ncbi.nlm.nih.gov/31237371/
- Donovan, J., Goldstein, B.G., & Goldstein, A.O. (2021). Treatment of androgenetic alopecia in men. In UptoDate. Hordinsky, M. & Ofori, A.O. (Eds.). Retrieved from https://www.uptodate.com/contents/treatment-of-androgenetic-alopecia-in-men
- Lepe, K. & Zito, P. M. (2020). Alopecia areata. [Updated Aug. 27, 2021]. In: StatPearls [Internet]. Retrieved on Dec. 3, 2021 from https://www.ncbi.nlm.nih.gov/books/NBK537000/
- Murphrey, M. B., Agarwal, S., & Zito, P. M. (2020) Anatomy, hair. [Updated Aug 11, 2021]. In: StatPearls [Internet]. Retrieved on Dec. 3, 2021 from https://www.ncbi.nlm.nih.gov/books/NBK513312/
- Phillips, T. G., Slomiany, W. P., & Allison, R. (2017). Hair loss: common causes and treatment. American Family Physician, 96(6), 371–378. Retrieved from https://pubmed.ncbi.nlm.nih.gov/28925637/
Dr. Steve Silvestro is a board-certified pediatrician and Manager, Medical Content & Education at Ro.