Hair Loss

Medically Reviewed By William C. Lloyd III, MD, FACS

What is hair loss?

Hair loss is the appearance of thinning hair or bald patches on the scalp, eyebrows, eyelashes, or on areas of the body that previously had hair, such as the arms or legs. On average, everyone naturally loses 50-100 of their 100,000 scalp hairs per day. Abnormal hair loss is caused when hair falls out at an accelerated rate, or when over time, hairs are not replaced as quickly as they fall out (Source: AAD).

Hair loss can happen to men, women, infants and children in all socioeconomic strata and geographic areas. Genetic hair loss (androgenetic alopecia) is the most common type of hair loss. Also known as male pattern baldness or female pattern baldness, it affects around 80 million people in the United States, according to the American Academy of Dermatology (Source: AAD). 

Hair loss can gradually build over weeks or months, or it can occur abruptly, such as when it occurs with telogen effluvium (sudden hair loss due to a stressful physical event). Hair loss can also be due to other hair disorders, such as alopecia areata, an autoimmune disease in which the body attacks its own hair, or trichotillomania, a psychological disorder in which people pull out their own hair.

Hair loss can also be a symptom of an underlying disease, disorder or condition such as anemia, thyroid disease, or lupus. Other underlying causes of hair loss may be more benign, such as use of certain harsh shampoos or hair colorants, or a nutritional insufficiency that can be easily corrected.

Hair is a significant component of personal appearance in our society. As such, hair loss can deeply affect your self-image and self-esteem. There are several different types of treatments for hair loss ranging from lifestyle changes to medications and surgery, and more are being researched every day. Fortunately in many cases, lost hair can be replaced with new hair growth with treatment or on its own in time.

Some causes of hair loss, such diabetes, can lead to life-threatening complications and can be fatal if they are undetected and untreated. Seeking regular medical care offers the best chances of discovering underlying diseases at their earliest, most curable stages. Seek prompt medical care if your hair loss is unexplained, is persistent, or causes you concern.

What other symptoms might occur with hair loss?

Hair loss can occur in conjunction with other symptoms, which vary widely depending on the underlying disease, disorder or condition. It is important to see your health care provider promptly if you are experiencing any of the following symptoms including:

  • Blurred vision, excessive hunger, excessive thirst, fatigue, or weight loss, which can be due to diabetes, an eating disorder, or poor nutrition

  • Itchy, raised and red patches on the scalp, which can be due to ringworm

  • Loss of facial or body hair, burning or itching of scalp, which can be due to alopecia areata

  • Rash over cheeks and the bridge of the nose, malaise, unexplained fever, mouth sores, and swollen lymph nodes, which can be due to lupus

  • Scalp itching, tightness or soreness, and dry brittle hair, which can be due to hypothyroidism or the use of styling products or tools

  • Sensitivity to cold, weight gain, fatigue, depression, dry brittle hair, joint or muscle pain, or heavier menstrual periods, which can be due to hypothyroidism

  • Sensitivity to heat, weight loss, jitteriness, irregular menstrual periods, and swollen glands, which can be due to hyperthyroidism

What causes hair loss?

The most common cause of hair loss is hereditary baldness, which medical providers call androgenetic alopecia or male pattern baldness or female pattern baldness. Other causes of hair loss range from specific hair disorders to other underlying diseases, medications, medical treatments, normal hormonal changes, stress, and poor nutrition.

Hair disorders

Hair disorders that can cause hair loss include:

  • Alopecia areata (autoimmune disease in which the body attacks its own hair and in which all the body hair can fall out)

  • Androgenetic alopecia (hereditary hair loss and the most common cause of hair loss)

  • Cicatricial alopecia (inflammation that scars and permanently destroys the hair follicles)

  • Telogen effluvium (sudden hair loss due to stressful events such as surgery, illness and birth)

  • Trichotillomania (psychological disorder in which people pull out their own hair and, in some cases, ingest the hair)

  • Various inherited structural hair disorders like monilethrix, and trichothiodystrophy

Other diseases, disorders and conditions that can cause hair loss

Hair loss can be caused by other diseases, disorders and conditions including:

  • Autoimmune disorders like systemic lupus and discoid lupus

  • Chronic iron deficiency

  • Diabetes

  • Hyperthyroidism (overactive thyroid)

  • Hypothyroidism (underactive thyroid)

  • Ringworm of the scalp (fungal infection)

  • Systemic lupus erythematosus (disorder in which the body attacks its own healthy cells and tissues)

    Medications and medical treatments that can cause hair loss

    Some medications and medical treatments can cause hair loss including:

    • Anabolic steroids (muscle-building steroids)

    • Birth control pills

    • Blood thinners

    • Chemotherapy

    • Radiation

    Hormonal events that can cause hair loss

    These normal hormonal changes can also cause you to temporarily lose hair, often abruptly:

    • Giving birth (hair loss after birth can occur to both the mother and the baby)

    • Menopause

    Everyday causes of hair loss

    Hair loss can arise from everyday causes including:

    • Poor nutrition (excessive intake of vitamin A, deficiencies in protein or iron)

    • Pregnancy

    • Stress from traumatic events, such as death, divorce, or illness

    • Overuse of hair cleaning and styling products, such as curling and straightening irons, hair spray, shampoo, harsh shampoos, hair colorant, permanents, and hair bands

    • Weight loss, especially rapid weight loss

    What are the potential complications of hair loss?

    Hair has significant importance in our society as a sign of health and attractiveness, so loss of your hair can greatly impact your self-image and self-esteem. Many underlying causes of hair loss can be treated, and you can help minimize your risk of complications of hair loss by following the treatment plan you and your health care professional design specifically for you.

    Complications of hair loss include:

    • Dry skin on the scalp

    • Embarrassment

    • Poor self-image and self-esteem

    • Stress

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    Medical Reviewer: William C. Lloyd III, MD, FACS
    Last Review Date: 2021 Jan 7
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    THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
    1. Allopecia areata. American Academy of Dermatology.
    2. Hair Loss. American Academy of Dermatology.
    3. Telogen Effluvium Hair Loss. American Osteopathic College of Dermatology.
    4. Breitkopf T, Leung G, Yu M, et al. The basic science of hair biology: what are the causal mechanisms for the disordered hair follicle? Dermatol Clin 2013; 31:1.