Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress.

Several terms redirect here. For other uses, see Balding (surname), Bald (disambiguation), and Alopecia (disambiguation)."Baldness" redirects here; not to be confused with Boldness.Medical condition

Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body.[2] Typically at least the head is involved.[4] The severity of hair loss can vary from a small area to the entire body.[7] Inflammation or scarring is not usually present.[4] Hair loss in some people causes psychological distress.[3]

Common types include male- or female-pattern hair loss, alopecia areata, and a thinning of hair known as telogen effluvium.[4] The cause of male-pattern hair loss is a combination of genetics and male hormones; the cause of female pattern hair loss is unclear; the cause of alopecia areata is autoimmune; and the cause of telogen effluvium is typically a physically or psychologically stressful event.[4] Telogen effluvium is very common following pregnancy.[4]

Less common causes of hair loss without inflammation or scarring include the pulling out of hair, certain medications including chemotherapy, HIV/AIDS, hypothyroidism, and malnutrition including vitamin B12 and iron deficiencies.[3][4] Causes of hair loss that occurs with scarring or inflammation include fungal infection, lupus erythematosus, radiation therapy, and sarcoidosis.[3][4] Diagnosis of hair loss is partly based on the areas affected.[4]

Treatment of pattern hair loss may simply involve accepting the condition, which can also include shaving one's head.[4] Interventions that can be tried include the medications minoxidil (or finasteride) and hair transplant surgery.[5][6] Alopecia areata may be treated by steroid injections in the affected area, but these need to be frequently repeated to be effective.[4] Hair loss is a common experience.[4] Pattern hair loss by age 50 affects about half of men and a quarter of women.[4] About 2% of people develop alopecia areata at some point in time.[4]

Terminology

Baldness is the partial or complete lack of hair growth, and part of the wider topic of "hair thinning". The degree and pattern of baldness varies, but its most common cause is androgenic hair loss, alopecia androgenetica, or alopecia seborrheica, with the last term primarily used in Europe.[citation needed]

Hypotrichosis

Hypotrichosis is a condition of abnormal hair patterns, predominantly loss or reduction. It occurs, most frequently, by the growth of vellus hair in areas of the body that normally produce terminal hair. Typically, the individual's hair growth is normal after birth, but shortly thereafter the hair is shed and replaced with sparse, abnormal hair growth. The new hair is typically fine, short and brittle, and may lack pigmentation. Baldness may be present by the time the subject is 25 years old.[8]

Signs and symptoms

Symptoms of hair loss include hair loss in patches usually in circular patterns, dandruff, skin lesions, and scarring. Alopecia areata (mild – medium level) usually shows in unusual hair loss areas, e.g., eyebrows, backside of the head or above the ears, areas the male pattern baldness usually does not affect. In male-pattern hair loss, loss and thinning begin at the temples and the crown and hair either thins out or falls out. Female-pattern hair loss occurs at the frontal and parietal.

People have between 100,000 and 150,000 hairs on their head. The number of strands normally lost in a day varies but on average is 100.[9] In order to maintain a normal volume, hair must be replaced at the same rate at which it is lost. The first signs of hair thinning that people will often notice are more hairs than usual left in the hairbrush after brushing or in the basin after shampooing. Styling can also reveal areas of thinning, such as a wider parting or a thinning crown.[citation needed]

Skin conditions

A substantially blemished face, back and limbs could point to cystic acne. The most severe form of the condition, cystic acne, arises from the same hormonal imbalances that cause hair loss and is associated with dihydrotestosterone production.[11]

Psychological

The psychology of hair thinning is a complex issue. Hair is considered an essential part of overall identity: especially for women, for whom it often represents femininity and attractiveness. Men typically associate a full head of hair with youth and vigor. People experiencing hair thinning often find themselves in a situation where their physical appearance is at odds with their own self-image and commonly worry that they appear older than they are or less attractive to others. Psychological problems due to baldness, if present, are typically most severe at the onset of symptoms.[12] Two meta analyses on androgenetic alopecia revealed psychosocial distress levels to be moderate, on average, rather than severe and that balding men were no more likely to have depression or self esteem issues compared to non-balding men.[13][14]

Hair loss induced by cancer chemotherapy has been reported to cause changes in self-concept and body image. Body image does not return to the previous state after regrowth of hair for a majority of patients. In such cases, patients have difficulties expressing their feelings (alexithymia) and may be more prone to avoiding family conflicts. Family therapy can help families to cope with these psychological problems if they arise.[15]

Causes

Although not completely understood,[citation needed] hair loss can have many causes: