12 Causes of Hair Loss In Men & Women 

Hair loss can be as psychologically upsetting as it is physically. It can affect the scalp and other areas of the body, leading to complete loss of hair in more severe cases. It’s important to understand the cause of your alopecia as early as possible to know the options that are available to you.

What Are the Causes of Hair Loss?

Hair loss can occur due to one or more of the following reasons: 

Androgenetic Alopecia

According to the American Academy of Dermatology Association (AAD), it is the most common cause of hair loss around the world. Both men and women can develop androgenetic alopecia. Studies have shown that its risk increases with age. People in their 30s have a 30% chance of developing it, while people in their 90s have a 90% chance of developing pattern baldness. 

This kind of hair loss results due to a combination of genetic, environmental, and hormonal factors. Research suggests that an “AR” gene increases the activity of the male sex hormone receptors, making them more sensitive to their presence. It is the conversion of testosterone into dihydrotestosterone (DHT) that causes the miniaturization and eventual shedding of the hair. 

The pattern of hair loss is different in both men and women. In males, it results in an “M” and then “U” shaped recession of the hairline with thinning of the crown. However, in females, a Christmas tree takes shape while the hairline is still intact. There are, of course, exceptions to this.

Alopecia Areata 

It is a chronic condition that occurs due to an autoimmune disorder. An individual’s immune system starts attacking its own healthy cells, including those in the hair follicles. This results in the formation of small, smooth, and circular coin-sized patches.

It is possible for people with alopecia areata to also have another autoimmune condition, such as lupus or vitiligo. Alopecia areata can also affect the nails in 10-15% of the cases. 

According to the National Alopecia Areata Foundation (NAAF), it can affect not just the scalp but also eyelashes, eyebrows, beards, and extremities and has the following types: 

  • Alopecia Totalis – Complete loss of scalp hair. 
  • Alopecia Universalis – Complete loss of entire body hair. 
  • Persistent Alopecia – Loss of hair in patches. It does not progress to alopecia totalis or universalis. 
  • Diffuse Alopecia – Thinning occurs all over the scalp and not just in one area. 
  • Ophiasis Alopecia – Loss of hair on the sides and back of the scalp. 

According to American Skin Association, about 20% of people with alopecia areata also have a relative with the same condition, suggesting a genetic basis. It can also be triggered by stress. The condition is relatively common. It has no cure; topical corticosteroid injections into the scalp are used for its treatment. 

Telogen Effluvium 

This is the kind of hair loss that occurs 3-4 months after the occurrence of a stressful event, which pushes 70% of the hair from the anagen phase of the growth cycle to the telogen phase. The “stress” in this case may be any of the following: 

This is another one of the most common causes of hair loss, as it can affect any person at any point in their life. However, women are likely to experience it more because of the hormonal changes that they experience. This kind of hair loss is sudden, and it can take 3-6 for regrowth to take place. 

Traction Alopecia

One of the common causes of hair loss in women is traction alopecia. The tension on the hair strands due to tightly-pulled back, curled, or knotted hairstyles can result in their breakage. 

According to the AAD, regrowth is not possible in this kind of hair loss. It is preventable, though. Because of certain hairstyles like braids, cornrows, and dreadlocks, traction alopecia is more common in African women. However, this can also affect men who wear their hair in tight buns or ponytails. Excessive grooming can also result in traction alopecia in the beard. 


Traumatic alopecia is what occurs when there is skin trauma on the scalp. This can be a result of the following: 

  • Accidents
  • Friction 
  • Extreme pressure
  • Chemical injury 
  • Heat damage 

This kind of hair loss is not always permanent. However, if the trauma is repeated over a long period of time, it can become irreversible. 

Chemotherapy or Radiotherapy 

Cancer treatments: chemotherapy and radiotherapy also cause hair loss. In chemotherapy, hair loss can affect any area of the body, no matter where the treatment is taking place. However, in the case of radiotherapy, hair loss occurs in the area where the treatment is taking place. While chemo hair loss is rarely permanent, radiotherapy hair loss is more common depending on the level of radiation you’ve received.


Falling in the spectrum of obsessive-compulsive disorder (OCD), trichotillomania is a repeated urge to pull the hair out from different areas of the body, including the scalp and facial hair. It is one of the causes of hair loss in both men and women, affecting them almost equally. Females, however, develop it earlier, around the age of 14, compared to males, who develop it around the age of 19. 

One way it is diagnosed (and distinguished from other causes of hair loss) is that the regrowth takes place at different lengths. This kind of hair loss can be permanent if done repeatedly for a long period of time.

Health Conditions 

There are many health conditions that result in the formation of plaques on the scalp. This can result in permanent, scarring alopecia. For instance, in lupus, the formation of discoid lesions can cause irreversible damage. 

Scalp psoriasis is another condition in which the patient develops plaques not just on the scalp but in different areas of the body. Regrowth is possible, but if it results in scarring, the damage is permanent.  


There are many changes that our hair experiences as we age. Their greying is the first thing that most people notice. However, the normal hair growth cycle is also affected; the duration of the anagen phase decreases, so the hair doesn’t grow as much anymore. The hair becomes thinner and thinner, and eventually, some follicles do not produce any hair at all. This is another common cause of hair loss in men and women. Almost everyone experiences a degree of thinning. This may occur in conjunction with androgenetic alopecia.


Before taking any medication, it’s best to discuss its possible side effects of it with the doctor. In the case of some medications, hair loss can occur on their intake. If you do learn that hair loss is a potential side effect of a medication, you shouldn’t simply stop taking it without consulting with your doctor. The medications for the following conditions can result in hair loss: 

  • Cancer
  • Arthritis 
  • Depression 
  • Cardiovascular disorders
  • Blood pressure
  • Gout 

It is possible to reverse the hair loss after you stop taking the medication. However, certain medications that cause hormonal changes in the body can result in hair loss that is permanent. For example, the intake of anabolic steroids for a long time can cause permanent hair loss due to androgenetic alopecia. 

Nutritional Deficiency 

Nutritional deficiency can cause hair loss by shocking the body, but it also causes hair loss by not providing building blocks for hair. In the case of iron deficiency, the hair is not getting enough oxygen. In addition, it is linked to other causes of hair loss, such as alopecia areata and androgenetic aloepcia. 

Vitamin D can affect the immune response. Therefore, its deficiency increases the risk of alopecia areata. Its deficiency has also been linked with pattern baldness. Lastly, since 85% of the hair is simply protein, if you’re not getting enough of it, you’re going to lose your hair. That’s why certain diets that restrict the intake of proteins have people experiencing hair loss due to this, in addition to telogen effluvium. 


There are different substances, the toxic levels of which can result in hair loss. These include: 

  • Thallium 
  • Mercury 
  • Selenium 
  • Lithium 
  • Cadmium 
  • Arsenic

The long-term inhalation or ingestion of certain substances in an industrial setting can also cause hair loss. 

To Sum Up 

Regardless of age, gender or ethnicity, hair loss can be a very distressing experience both emotionally and physically. 

Knowing the different causes of hair loss may help you identify the one which you may be suffering from. In any case, you need to consult a dermatologist about this as soon as possible, as your hair loss may be indicative of an underlying health condition. Moreover, in some cases, a lack of early intervention can make hair loss irreversible. 

All of these causes of hair loss can affect men and women. Some types, however, affect more men than women and vice versa. Some hair loss is inevitable and unavoidable, while others you can prevent. 

Reviewed and Approved by Dr. Hassan Soueid.

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