13 Medical Reasons for Hair Loss (Men and Women)

Medical Reasons for Hair Loss

Medical Reasons for Hair Loss (Men and Women) explores 13 medical conditions that can lead to hair loss. Though much hair loss is genetic, there are medical conditions that can lead to hair loss. The good news is many times, but not always, once the medical issue is resolved, hair growth resumes.

Because of this medical component, it’s essential to consult with a doctor to find the underlying cause of hair loss. This post is for information only and should not be used to diagnose.

Hair Growth Cycle

To understand how certain health conditions can result in hair loss, it can be helpful to understand hair growth and its cycle.

  1. Hair Begins Growing at the Root of a Hair Follicle
  2. Blood Vessels Feed the Root Making Hair Grow
  3. Hair Pushes Up and Out
  4. Hair Continues to Grow
  5. Hair Falls Out as New Regrowth Hair Cycle Starts

Any disruption along the growth cycle can cause hair loss.

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Alopecia Areata

Medical Reasons for Hair Loss (Men and Women) - Alopecia

Alopecia Areata is an immune disorder where the immune system attacks the hair follicle. The cause is unknown, but genetics seem to play a part.

  • There does seem to be a few predispositions to the likelihood of experiencing alopecia areata:
    • Asthma
    • Down Syndrome
    • Family History
    • Pernicious Anemia
    • Seasonal Allergies
    • Thyroid Disease
    • Vitiligo

Though alopecia areata cannot be cured, it can be treated. Treatments such as anti-inflammatory drugs, topical immunotherapy, and Minoxidil, more commonly known as Rogaine, have been effective in some cases.


  • An Autoimmune Disorder
    • With Autoimmune Disorders, the Body Attacks Itself
  • Seen In Both Males and Females
  • Hair Falls Out in Patches
  • Possible Genetic and Other Predispositions
  • Most Often Seen in Ages 30-60
  • Rare Before Age Three
  • Not Curable but Treatable

Scarring Alopecia

Scarring Alopecia includes a group of hair loss disorders in which the hair follicle is destroyed and replaced by fibrous tissue or scar tissue. This destruction of the hair follicle is permanent.

There is no known cause for scarring alopecia. At this time, there is no known treatment to reverse the hair loss. Because of this, the goal of treatment is to prevent further hair loss.

Approximately 7% of patients seen at hair loss clinics experience scarring alopecia.


  • Destroys the Hair Follicles and Replaces Them with Scar Tissue
  • Hair Loss Permanent
  • Early Adult Onset
  • Adolescent and Childhood Onset is Rare

Anagen Effluvium

Medical Reasons for Hair Loss - Anagen Effluvium

Anagen Effluvium is the shedding of hair that takes place during the hair growth stage of the hair cycle. It usually occurs when the individual comes in contact with a toxin. Once the toxin is removed hair growth usually resumes.

Treatments to help in the regrowth of hair include a topical minoxidil solution and scalp cooling during chemotherapy.


  • Hair Shedding During Hair Growth Stage
  • Commonly Caused By:
    • Autoimmune Disease
    • Chemotherapy
      • Stops 3-6 Months After Chemotherapy Has Stopped
    • Radiation
    • Exposure to Chemicals/Poisons- Such as Thallium, Boron, and Arsenic
    • Infection
  • Once Exposure of Cause is Stopped, Growth Usually Begins
    • Change of the Color and Texture New Hair May Occur.

Child Birth

Medical Reasons for Hair Loss (Men and Women) - Child Birth

Pregnancy and giving birth can cause hormones to fly all over the place.

During pregnancy, the body has higher levels of both the hormones progesterone and estrogen. These higher levels cause hair to stay in the growth period of the hair growth cycle. Once birth occurs, these hormones shift to normal levels, and hair stays in the resting stage of the growth cycle for about three months and then begins to shed.

The hair loss seen postpartum isn’t actual hair loss; it is excessive hair shedding. Nonetheless, it can be troublesome for some new moms. Be assured this is a common occurrence and will usually reside 6-12 months after giving birth.


  • Common and Usually Temporary
  • Most Dramatic 3 Months Postpartum
  • Subsides 6-12 Months Postpartum

Hormonal Imbalance

Medical Reasons for Hair Loss (Men and Women) - Hormone Imbalance

Hormones are chemical messengers that send messages through the bloodstream to another part of the body. Hormones affect many physiological activities, including appetite, growth, metabolism, puberty, and fertility.

Both men and women have estrogen, progesterone, and testosterone. Men have a more significant percentage of testosterone and less estrogen and progesterone, while women have lower amounts of testosterone and more estrogen and progesterone.

When found in the hair follicles, the male hormone testosterone converts into DHT (dihydrotestosterone) that deactivates the hair follicle. This causes the hairs to stop growing as they usually would and eventually fall out.

Cortisol is known as the stress hormone. Having higher cortisol levels can interfere with the hair growth cycle as it regulates the cycle of the hair follicle.

Another hormone is insulin which controls glucose levels in the bloodstream. Insulin resistance is thought to play a part in hair loss though studies haven’t found how or why.

Hair loss due to hormonal imbalance is reversible. Topical Minoxidil is the most often used treatment for hormonal hair loss.


  • Cortisol
    • Stress Hormone
    • Affect the cyclic regulation of the hair follicle during the hair growth cycle.
  • Estrogen
    • Hormone found in higher levels in women than men
  • Progesterone
    • Hormone found in higher levels in women than men
  • Testosterone
    • Hormone found in higher levels in men than women.
  • Menopause
    • As women experience perimenopause and menopause there is a natural decrease in estrogen and progesterone (female hormones). With this there is also an increase in the effects of testosterone (male hormone). Testosterone found in the hair follicles is converted into DHT (dihydrostertosterone) which is a hormone that can inactivate the hair follicles which then leads to hair loss.
  • Insulin Resistance
    • Insulin regulates glucose in the blood stream
    • There are studies that suggest that insulin resistance contributes to hair loss, however, studies haven’t found the reason why or how.

Medical Treatments & Surgery

Medical Reasons for Hair Loss - Chemotherapy

Surgery and other medical treatments put the body under a great deal of stress, so it’s no wonder one of the side effects can be hair loss.

Hair loss experienced after surgery usually lasts anywhere from 1-3 months, and then the hair will resume normal growth.

Other medical treatments such as chemotherapy and radiation, normal hair growth should return once the treatment ends as the body begins to rebuild its immune system.


  • Chemotherapy
    • Regrowth starts 3-6 months after completion.
  • Radiation
    • Regrowth starts 3-6 months after completion.
  • Major Surgery
    • Increased Hair Shedding Within 1-3 Months After Surgery
    • Generally Reverses Itself After a Few Months


Medical Reasons for Hair Loss - Medication

Hair loss caused by medications usually occurs three months after starting the medication.

Opposed to patchy hair loss, when medications are the cause of hair loss, it is usually seen as thinning hair occurring on the top of the scalp.

Most of the time the hair loss is experienced in the hair resting and growth phase of the hair cycle.
Once the medication is stopped, hair growth usually resumes within 3-18 months.

Common Drugs Causing Possible Hair Loss include:

  • Amphetamines
  • Beta-Blockers
    • Propranolol (Inderal)
    • Metoprolol (Lopressor or Toprol XL)
  • Dextroamphetamine (for example, Dexedrine
  • Arthritis Medicines
    • Indomethacin
  • Birth Control Pills
  • Bipolar Medications
    • Lithium
  • Blood Thinners
    • Warfarin
    • Heparin
  • Chemotherapy
  • Gout Medicine
    • Allopurinol
    • Colchicine
  • Methamphetamine
  • Seizure Medicines
    • Valproic Acid
    • Carbamazepine
    • Trimethadione


Medical Reasons for Hair Loss - psoriasis

Psoriasis is a genetic autoimmune disease that causes plaques, which are itchy or sore patches of thick, dry, discolored skin. The immune system, which usually attacks infectious germs — begins to attack healthy cells instead.

When psoriasis occurs on the scalp, it can lead to hair loss. Though psoriasis doesn’t directly affect the hair follicles, the inflammation caused by scratching can loosen the hair follicle.

There is no cure for psoriasis, but it can be treated and has been known to go into remission. Once psoriasis is treated, hair loss usually stops.


  • Temporary
  • Usually Resolves when Psoriasis is Treated


Medical Reasons for Hair Loss - Ringworm

Ringworm is a fungal infection. When the scalp is the site of infection, it causes itchy, dry/flaky, bald patches.

Ringworm is more common in children than adults and is highly contagious.

Hair loss occurs due to high levels of inflammation of the scalp. As the infection worsens, the fungus gets into the hair fibers. The hair becomes brittle and breaks off easily, leaving a bald patch of skin.

Treatment is usually an antifungal medication. Left untreated, ringworm can cause permanent hair loss.


  • Fungal Infection
  • Highly Contagious
  • More Common In Children
  • Bald Patches
    • Itchy and Scaly
    • Hair Loss May Be Permanent
  • Treatment – Antifungal Medication


Medical Reasons for Hair Loss - Syphilis

Syphilis is a highly contagious disease that’s mostly spread through sexual activity.

Sexually transmitted diseases usually do not cause hair loss. However, left untreated, syphilis can cause patchy hair loss on the scalp, eyebrows, beard, and elsewhere.

Once syphilis is successfully treated, hair will usually grow back.


  • Syphilis
    • Hair Loss if Experienced Usually Occurs in the Second Stage
    • Can Be Treated
    • Once Immune System Recovers Hair Will Usually Grow Back

Telogen Effluvium

Medical Reasons for Hair Loss - Telogen Effluvium

Telogen effluvium is temporary hair loss that happens after a traumatic event, shock, or some type of stress. This leads to the hair growth cycle to go into resting for a period of time.

Telogen effuvium usually resolves itself anywhere from 3 to 6 months. Hair growth usually begins again.


  • Caused by Trauma, Shock, or Stress
  • Temporary Hair Loss
  • Resolves in 3 to 5 Months


Medical Reasons for Hair Loss - Thyroid

The thyroid is a gland located in the lower neck. The thyroid plays a prominent role in the development, growth, and metabolism of the body by releasing hormones into the bloodstream.

When the thyroid’s hormonal process is not balanced correctly, it can cause many health issues.

When the thyroid doesn’t release enough hormones, it is called hypothyroidism, aka an underactive thyroid. Among other things, this can cause weight gain and hair loss.

When the thyroid releases too much of the hormones, it is called hyperthyroidism, aka overactive thyroid. With hyperthyroidism, among other symptoms, you might see unintended weight loss, irregular heartbeat, and nervousness.

Both hyperthyroidism and hypothyroidism can cause hair loss. Usually, with proper treatment, hair loss is temporary.


  • Hyperthyroidism – Overactive Thyroid
  • Hypothyroidism – Underactive Thyroid
  • Involves Entire Scalp
  • Reversible with Treatment
  • Thyroid Imbalance
    • Hypothyroidism and hyperthyroidism can cause hair to fall out.
    • In most cases, the hair will grow back once the thyroid disorder is treated.

Vitamin Deficiency

Medical Reasons for Hair Loss - Vitamin Deficiency

Being deficient in either Iron, Zinc, or Vitamin D can cause hair loss.

Iron is essential in the production of hemoglobin. Hemoglobin is a protein in your red blood cells that carries oxygen throughout the body. This includes delivering nutrients and oxygen to hair follicles. Without enough iron in the body, hair won’t grow.

Zinc plays a significant role in hair tissue growth and repair. Zinc also helps keep the oil glands around the follicles working properly. A Zinc deficiency can cause hair loss and may also damage any remaining hair, causing it to break.

Vitamin D is the vitamin that stimulates hair follicles. If not enough Vitamin D is present new hair growth can be stunted.


  • Iron
    • Contributes to the Production of Hemoglobin
    • Hemoglobin Helps Deliver Nutrients and Oxygen to Hair Follicles
    • Without Enough Iron, Hair Won’t Grow
  • Zinc
    • Contributes to Hair Tissue Growth and Repair
    • Contributes to Healthy Oil Glands Around Hair Follicles
    • Hair Loss and Hair Breakage
  • Vitamin D
    • Stimulates New and Old Hair Follicles
    • If Deficient in Vitamin D, New Hair Growth Can Be Stunted


If you are interested in learning more about hair regrowth treatments another article you might find beneficial is:

In reading Medical Reasons For Hair Loss (Men And Women), you explored 13 medical causes of hair loss. Many times the normal hair growth cycle can be restored once the underlying cause is found and treated. Remember to consult a doctor to get a diagnosis before beginning any treatment.

Do you have any stories or experience in medical-driven hair loss? I would love to hear your story. Please comment below.

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