What Causes Hair Loss?

Doctor Answers 5

Hair loss has many causes

There are many different causes of hair loss, all with different treatments. We will cover the more common causes below.

The most common cause of hair loss, or alopecia, is often referred to as male-patterned baldness. More appropriately, this condition is termed androgenic alopecia, and can affect women as well as men. Twenty-five percent of men aged 25 years have some degree of clinically apparent androgenic alopecia and over 40% of men will develop androgenic alopecia at some point in their life. Androgenic alopecia results from progressive shortening of the anagen cycle, the part of the hair cycle responsible for hair growth, with resultant decreased time for hair growth.

Hair loss usually begins with the frontoparietal scalp and then the vertex. Female-pattern baldness is similar but more diffuse, without complete baldness and maintaining the anterior hairline.

Fortunately hairs on the sides and back of the scalp are androgen-independent and thus do not suffer from androgenic alopecia - it is these hairs which are used for hair transplants and why hair transplants last.

Androgenic alopecia is genetically determined and its development is related to age and presence of hormones and the corresponding receptors.

The second most common form of alopecia is alopecia areata. This form of hair loss results in rapid loss of hair in circular or oval patches. It may be episodic or persistent. There is no definite reason why alopecia areata develops, but there is a genetic predisposition, and popular opinion favors an autoimmune disorder.

Alopecia areata only affects 0.1% of people. Approximately 3 months after surgery, childbirth, crash dieting, other stressful events, hair can enter an extended resting cycle referred to as telogen effluvium. Usually <50% of the scalp is affected and recovery is complete once the triggering event is resolved.

A wide range of medications can cause hair loss. The most widely known are chemotherapy drugs but other more common drugs, including blood thinners and Vitamin A, can cause hair loss. After taking the medications, hair growth is abruptly interrupted and growing hairs are shed after 1-4 weeks. This form of hair loss rapidly affects 80-90% of the scalp but complete recovery can be expected once the medication is stopped.

Certain infections can cause hair loss. Children may have hair loss caused by a fungal infection of the scalp. The infection is easily treated with antifungal medicines.

Hair loss may occur as part of an underlying disease, such as lupus or diabetes. Since hair loss may be an early sign of a disease, it is important to find the cause so that it can be treated.

Finally, tightly pulling hair can cause hair loss. People who wear pigtails or use tight hair rollers can pull the hair and cause traction alopecia. If the pulling is stopped before scarring of the scalp develops, the hair will grow back normally. However, scarring can cause permanent hair loss. Hot oil hair treatments or chemicals used in permanents may cause inflammation (swelling) of the hair follicle, which can result in scarring and hair loss.

Dallas Facial Plastic Surgeon
3.9 out of 5 stars 14 reviews

Cause of Hair Loss

Most people naturally shed about 50 to 100 hairs a day, but sometimes men and women can shed much more, leading to thinning hair, hair loss, and over time, baldness. The causes of this hair loss can be a result of hormones, underlying medical conditions, and even certain medications like antidepressants, high-blood pressure medications, and NSAIDS (non-steroidal anti-inflammatory medications). Sometimes, hair loss is purely genetic and can run in families. While hair loss is often referred to as alopecia areata (the medical name for hair loss), this term cannot be used to describe all hair loss. Alopecia areata is an autoimmune disease where the immune system attacks the hair follicles, causing hair to fall out in small circular patches.
What’s important to know: the cause of hair loss is specific to each individual, which is why it is so important to have a board-certified dermatologist examine, diagnose, and treat your condition. Our board certified dermatologists will review your symptoms, examine your scalp, perform a possible scalp biopsy, and/or order medical and blood tests if an underlying medical condition (like thyroid disease, diabetes, or autoimmune diseases like lupus) is suspected.

Dennis Gross, MD
New York Dermatologist
4.4 out of 5 stars 5 reviews

There are may causes for hair loss. It is like asking what causes death.

There are may causes for hair loss.  It is like asking what causes death.  It can range from bad luck to genetic to numerous medical conditions to start.

Jae Pak, MD
Los Angeles Hair Restoration Surgeon
5.0 out of 5 stars 100 reviews

Causes of Hair Loss

Hair loss has many, many different causes. The leading cause in both men and women is androgenic alopecia (pattern baldness), however, there are several others, including (but not limited to):

  • traction alopecia
  • malnutrition
  • anemia
  • thyroid dysfunction
  • diabetes
  • telogen effluvium
  • drug use
  • pregnancy
  • lack of sleep
  • trichotillomania
  • lupus

Sanusi Umar, MD
Redondo Beach Dermatologic Surgeon
4.6 out of 5 stars 32 reviews

Hair Loss Causes

There are many common causes for hair loss. Among them are changes in hormone levels, increased stress, or illness, scalp and dermatological issues, certain medications, and of course heredity. Even a poor diet can lead to increased hair loss.  Your hair restoration provider will provide a detailed medical history and physical to determine cause and ultimately recommend treatment options.



Edward E. Dickerson, IV, MD
Fayetteville Facial Plastic Surgeon
4.7 out of 5 stars 120 reviews

These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.