What Causes Hair Loss and Thinning in Women and Men?

Medically reviewed by William Truswell, MD

There are various reasons you could be losing your hair. Genetics, certain illnesses or conditions, hormonal changes, medications, and stress are among many factors that can cause this issue, known clinically as alopecia. Although hair loss is often associated with male pattern baldness, hair loss isn’t just a “male” issue.

Though hair loss can’t always be reversed, knowing what’s at the root of hair loss is critical in managing it. This article discusses factors that lead to thinning hair or bald spots, who’s at risk, and how to treat it.

What Causes Hair Loss in Women?

Losing hair follicles is a normal part of the hair growth cycle. In their final, full-grown phase—the telogen phase—hair follicles stay dormant for up to three months, falling off when new hair starts to grow. Hair loss occurs when something disrupts this cycle, and hair follicles stop regrowing. In women, a wide range of health factors contribute to this issue.

Types of Hair Loss

Hair thinning and balding, though appearing different, are both forms of hair loss occurring in varying degrees. Hair loss can be gradual or rapid, depending on the case. Healthcare providers break hair loss into several types:

• Androgenetic alopecia: Also known as pattern baldness, changes in androgen hormone cause hairline or top-of-the-head hair loss in men and hair thinning in women.

• Anagen effluvium: Rapid hair loss that is a common side-effect of chemotherapy.

• Telogen effluvium: A rapid and sudden form of hair loss caused by stress, medications, or sudden hormone changes.

• Alopecia areata: A form of hair loss that occurs when the immune system mistakenly attacks hair follicles. It can cause bald patches or affect the entire scalp, face, and body.

Genetics

The most common cause of male and female hair loss is androgenetic alopecia, or hereditary pattern balding. Androgenetic alopecia is genetic and is caused by a reaction to androgen and occurs after puberty. It causes gradual hair loss; in women, this is more likely to cause diffuse thinning on the top of the head.

Hair Styles

Certain hairstyles can stress the hair follicles, leading to a form of hair loss called traction alopecia. While anyone can be affected, this issue is common in women who wear braids, tight pony tales, or corn rows. Over time, traction alopecia can lead to permanent hair loss.

Hair Products

Chemical hair products and treatments can cause permanent hair damage. Women typically see hair loss related to hair products more often than men. If done improperly and with the wrong products, chemical hair curling, bleaching, relaxation treatments, coloring, or perming can cause hair loss.

Nutritional Deficiencies

Researchers have also found vitamin and mineral deficiencies related to hair loss. Anemia (iron deficiency), a condition common among women, can contribute to hair loss. Furthermore, researchers have linked insufficient selenium, zinc, vitamin B12, riboflavin, and vitamin D to alopecia.

Aging

Natural hormonal shifts as you age can bring on hair loss. In women, androgenic alopecia can start to set on during the reproductive years, occurring later than it does in men. At 29, 12% of women start showing signs, but by 79, over half show symptoms.

Hormonal Changes

Changes in estrogen levels can shock the system, leading to telogen effluvium. This type of hair may result from medications or other health changes, including:

• Pregnancy

• Hormone replacement therapy

• Birth control pills

• Crash diets

Stress

Extreme stress can also cause telogen effluvium. In women, this can be brought on by the physical shock of giving birth, emotional distress, mental illness, surgery, or certain diseases.

Menopause

Menopause, when the menstrual cycle stops, causes changes in estrogen and testosterone—hormones involved in regulating the hair cycle. Typically setting on when women are between 45 and 55, these fluctuations can trigger female pattern hair loss.

Rapid Weight Loss

Sudden weight loss and very restrictive diets can also cause telogen effluvium. In men and women, such hair loss can accompany rapid weight loss following bariatric surgeries, such as gastric bypass.

Chemotherapy or Medications

Another cause of rapid hair loss in women and men is anagen effluvium from chemotherapy or radiation treatment for cancer or certain medications. The hair loss, which can affect the entire body, starts two to three weeks after therapy. Most people can regrow their hair after stopping treatment.

In addition, too much vitamin A and certain medications can also cause telogen effluvium. Of the latter are beta-blockers (e.g., Inderal), retinoids, anticoagulants (Warfarin and others), and Carbatrol (carbamazepine).

Autoimmune Diseases

Affecting men and women, alopecia areata occurs when the immune system mistakenly attacks hair follicles. This autoimmune disorder typically causes round, bald patches. In addition, skin disorders, such as psoriasis, can spread to the scalp, affecting hair growth.

Other Conditions

Several other conditions, including the following, can also cause hair loss:

• Ovarian tumors or polycystic ovary syndrome can boost testosterone production in the ovaries, leading to pattern baldness.

• Burns or other skin conditions affecting men and women can cause hair loss.

• Tinea capitis (ringworm) is a fungal infection that causes round, bald patches on the scalp.

• Hypothyroidism is a condition caused by an underactive thyroid and contributes to hair loss, though the mechanism behind this is not well understood.

• Trichotillomania, or hair-pulling disorder, is a compulsive need to pull hair from the scalp, eyebrows, or other body parts.

What Causes Hair Loss in Men?

In men, hair loss is often caused by reactions to the predominant male reproductive hormone, testosterone. Many factors affect these levels, with other diseases or conditions leading to different types of hair loss.

Genetics

Most hair loss in men is caused by androgenetic alopecia or male pattern hair loss. This type is genetic—passed from parent to child—and progresses gradually. It typically affects the hairline, temples, or top of the head. Linked to the activity of the androgen receptor (AR) gene, up to 50% of male adults experience some form of this by age 50.  

Aging

As in women, hair loss in men can be a natural result of changes in the body due to aging. Healthcare providers refer to age-related hair loss as "senescent alopecia," which differs from male pattern hair loss. Researchers have observed hair mild follicle shrinkage, resulting in thinner individual hair strands.

Chemotherapy and Medications

Men also experience anagen and telogen effluvium in response to chemotherapy, radiation therapy, or certain medications. In these cases, the hair loss is often reversible when medication or treatment is stopped.

Stress Reactions

Infections, distressing events, high fever, and mental health issues can contribute to stress-related hair loss in men and women. Rapid weight loss due to bariatric surgery or disease can also cause this often reversible condition.

Nutrition

Dietary factors and nutrition can also play a role in male hair loss. For men, deficiencies in zinc, niacin, and protein and excess intake of vitamins A and E have been linked with male pattern baldness and other types of hair loss.

Sudden or Progressive Hair Loss: Who Is At-Risk?

Since there are many types of hair loss and many factors that can cause it, it’s important to understand who is at more risk. Certain health conditions raise your risk of both sudden hair loss (like telogen or anagen effluvium) and progressive hair loss (androgenetic alopecia).

Risk Factors for Sudden Hair Loss

Several factors can increase your chances of developing telogen or anagen effluvium, which causes sudden shedding of hair. You're at an increased risk for sudden hair loss if any of the following apply:

• You've recently given birth or had surgery

• You have a severe infection or illness

• You've changed birth control or other hormone-based medications

• Your diet is lacking in iron and protein

Risk Factors for Progressive Hair Loss

Several health conditions and diseases raise your risk of pattern baldness and alopecia areata. Factors associated with this issue include:

• A history of smoking or using tobacco products

• Being over 70 (for androgenetic alopecia)

• Being between your 20s and 40s (for alopecia areata)

• A family history of pattern hair loss

• Being white

• Having an autoimmune condition, such as psoriasis, lupus erythematosus, and others

• Eating a diet lacking in protein, iron, and other nutrients

Can You Stop Hair Loss Once It Begins?

With some types of hair loss, like androgenetic alopecia, the changes to the hair are permanent. While you can take steps to slow this process, the physical changes in your body make it difficult to stop losing hair entirely. The earlier you treat hair loss, the better the outcome.

But with other types, such as telogen and anagen effluvium, hair loss is reversible. So long as the underlying cause is treated or stopped, you can expect regrowth. However, it can take up to six months before you notice results.

Steps to Treat Hair Loss Based on Cause

If you experience pattern balding, seeing a healthcare provider for care and diagnosis is essential. Treatments depend on the underlying cause, and what’s effective varies from person to person. Everything from starting medications to stopping others and starting therapies for contributing diseases can play a role.

Androgenetic Alopecia Treatments

For androgenetic alopecia, your healthcare provider may indicate topical medications to help prevent further hair loss. Rogaine (minoxidil) formulations are effective for female and male pattern hair loss. You apply this solution indefinitely, as results go away if you stop.

Alpha-reductase inhibitors, such as Propecia (finasteride) and Avodart (dutasteride), are additional options for male pattern hair loss.

Alopecia Areata Treatments

While alopecia areata typically resolves on its own, medications can help manage the hair loss faster. For this condition, regular corticosteroid injections are frontline therapy. Other medications include:

• Topical corticosteroids

• Drithocreme (anthralin)

• Immunotherapy (diphenylcyclopropenone, squaric acid dibutyl ester)

• Barcitinib and Ritlecitinib (oral Janus kinase [JAK] inhibitors)

Treatments for Anagen and Telogen Effluvium

When it comes to effluvium—rapid hair shedding due to physical or emotional stress—treatments focus on finding the underlying cause. If a medication or disease is at the root, treatments focus on those. For anagen effluvium, caused by cancer treatment, there’s some evidence that cooling the scalp during chemotherapy may help preserve hair.

Treatments for Tinea Capitis

For tinea capitis, a fungal infection, you’ll need antifungal medications. Topical solutions typically don’t work, so your healthcare provider may prescribe one of the following oral formulations:

• Lamisil (oral terbinafine)

• Sporanox (itraconazole)

• Diflucan (fluconazole)

• Griseofulvin

A healthcare provider may also recommend Nizoral (ketoconazole), an over-the-counter (OTC) antifungal shampoo.

Summary

Many conditions cause hair loss in men and women. Genetics is the most common cause, with others including autoimmune diseases, physical or emotional stress, cancer treatments, and medications. Depending on the underlying cause of hair loss, this condition may or may not be reversible. Some medicines can prevent hair loss or spur growth, making proper diagnosis critical.

Read the original article on Verywell Health.