Classified as scarring or non scarring, diffuse or focal.

Can be caused by genetics, hormones, thyroid abnormalities, medications, hypervitaminosis A, autoimmune diseases, nutritional deficiencies, and infections.

Hair loss is a common occurrence. 

While it’s more prevalent in older adults, anyone can experience it, including children.

Hair loss can develop gradually over years or happen abruptly. 

Hair may be temporary or permanent, depending on the underlying cause.

Hair loss, it can be the result of genetics, internal causes, or external causes.andra

Most common infectious causes include fungal or systemic infections, like HIV or syphillis.

Non-scarring alopecia is a category of hairless most frequently encountered in primary care.
Scarring alopecia is characterized by permanent destruction of follicular structures, presents with prurtitus , pain, erythema, scale, and or crust and obliteration of follicular pore markings leading to an abnormally smooth appearance of the skin.
Scarring alopecia may require a scalp biopsy for diagnosis.

Tines capita can cause focal scarring hair loss in children.

Diffuse hair loss occurs uniformly across the entire scalp.
Telogen effluvium Is the most common cause of diffuse scalp hair loss.

Telogen effluvium is a stress related disorder of diffuse hair loss.

Telogen effluvium may be related to an inciting event: acute severe or chronic illness, major surgery, thyroid disease, pregnancy, iron deficiency, malnutrition, rapid weight loss, vitamin D deficiency, certain medications including lithium, sodium valproate, fluoxetine, warfarin, metaprolol, propranolol, retinoids, isoniazid, discontinuation of estrogen containing oral contraceptives.
In telogen effluvium hair sharing occurs 2-4 months after the inciting event.
Telogen effluvium  is typically self limited, and shedding takes 6-9 months to normalize.

Telogen effluvium Leads to a loss of greater than 200 scale hairs a day.

Estimated 35 million men and 21 million experience hair loss.

Hair loss sufferers lose on average 100 follicles per day.

By age 60 years 65% of men and 80% of women will have noticeable hair loss.

Non-scarring  hair loss is described as to the distribution of the loss of scalp hair as patterned, diffuse, or focal.

Hair loss-baldness

Patterned hair loss: thinning hair occurs symmetrically and most notably at the front, top, and size of the scalp, well graded density is retained at the back of the scalp in the occipital area.
Frontal temporal hairline thinning of hair occurs in both sexes, but is more pronounced in men.
In patterned hair loss follicles miniaturize to become finer and grow less long.

Androgenic alopecia refers to hereditary hair loss, like male pattern baldness or female pattern baldness.

It’s also the most common cause of hair loss, affecting up to 50% of people.

Hair loss related to androgenic alopecia tends to happen gradually. 

Female pattern baldness often results in thinning all over the scalp and might look like widening or thinning around the part. 

It typically occurs after age 65 but, for some females, it can begin early in their lives.

Androgenetic alopecia is the most common form of patterned hair loss.
Androgenetic alopecia begins at puberty with follicular miniaturization mediated by androgen dihydrotestosterone.

Male pattern baldness typically involves progressive hair loss above the temples and thinning at the crown of the head, creating an “M” shape.

Androgenetic alopecia is a heritable polygenic trait.

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.

Close to 1 out of every 4 men in the U.S. starts to go bald by age 30.

The severity of hair loss can vary from a small area to the entire body.

Typically inflammation or scarring is not present.

Male-patterned balding typically starts with a slowly receding hairline and balding on top of the head.

Other types of hair loss may not follow a particular pattern, be patchy, or occurs on parts of the body other than the head.

Thinning hair on top of your head may be noted especially with female-pattern baldness.

Hereditary hair loss affects about 80 million men and women in the U.S.

Focal hair loss occurs in discrete patches on the scalp and sometimes on the face and body.

Alopecia areata is the most common type of focal hair loss.

Alopecia areata is an autoimmune condition that causes the immune system to attack hair follicles, resulting in bald patches that can range from small to large.

In addition to losing hair on the scalp, some people with alopecia areata lose hair from their eyebrows, eyelashes, or other parts of the body.

The autoimmune disorder alopecia areata affects about 4.5 million people in the U.S. at some time in their lives.

Pattern hair loss by age 50 affects about half of males and a quarter of females.

About 2% of people develop alopecia areata at some point in time.

There are many types of balding, from typical male balding to the balding caused by chemotherapy.

Male-pattern baldness, is the most common type of hair loss.

Male-pattern baldness can progress over a period of years.

The earlier male-pattern baldness begins, the greater the likelihood of increased baldness.

Other types of hair loss, such as that caused by the physical stress of an illness or surgery, can happen suddenly.

May be a result of a medical condition such as lupus or diabetes.

Alopecia areata is an autoimmune disease that causes hair to fall out in patches from the scalp and other areas of the body.

Alopecia areata often causes a sudden loss of hair in one spot.

Some types of hair loss are permanent.

Others types of hair loss can reverse themselves or can be reversed with proper treatment.

With male-pattern balding, men, usually lose hair on top, with just a little remaining on the sides of the head.

Women usually have thinning hair on top, and may have some bald patches.

Physical stress induced hair loss may occur several months after the illness or surgery is over.

Chemotherapy induced with chemotherapy typically starts a few weeks after treatment starts, and hair usually grows back 2-3 months after treatment stops.

Hair loss may be caused by: too much vitamin A, not enough protein or iron, certain medications, harsh hair-care techniques, pulling out of hair, certain medications including chemotherapy, HIV/AIDS, hypothyroidism, and malnutrition.

Thinning of hair known as telogen effluvium.

The cause of male-pattern hair loss is a combination of genetics and male hormones.

The cause of female pattern hair loss is unknown.

The cause of alopecia areata is autoimmune.

The cause of telogen effluvium is typically a physically or psychologically stressful event, and is very common following pregnancy.

Hair loss that occurs with scarring or inflammation include: fungal infection, lupus erythematosus, radiation therapy, and sarcoidosis.

Treatment of pattern hair include: acceptance, Interventions medications minoxidil, or finasteride and hair transplant surgery.

Minoxidil solution is approved in men and women and is associated with a greater improvement in hair density per centimeter squared.

Up to 15% of patients who use topical minoxidil experience transit hair shading in the first few months of treatment and 2-5% of women develop unwanted facial hear that resolves with treatment discontinuation.

Minoxidil solution is applied directly to the scalp, dilates blood capillaries, and may promote hair follicle growth by allowing more blood, oxygen, and nutrients to reach them.

Minoxidil is safe for both men and women.

Alopecia areata may be treated by repeated steroid injections in the affected area.

Hypotrichosis is a condition of abnormal hair patterns.

Hypotrichosis refers to predominantly loss or reduction of hair that occurs most frequently, by the growth of vellus hair in areas of the body that normally produce terminal hair.

In hypotrichosis hair growth is normal after birth, but shortly thereafter the hair is shed and replaced with sparse, abnormal hair growth.

The new hair growth is typically fine, short and brittle, and may lack pigmentation.

Baldness may be present by the time the subject is 25 years old.

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, and to maintain a normal volume, hair must be replaced at the same rate at which it is lost.

At first signs of hair thinning that people will often notice are more hairs than usual left in the hairbrush, or in the shower.

Cystic acne, arises from the same hormonal imbalances that cause hair loss and is associated with dihydrotestosterone production.

Seborrheic dermatitis, a condition in which an excessive amount of sebum is produced and builds up on the scalp, is also a symptom of hormonal imbalances, as is an excessively oily or dry scalp.

Both cystic acne and seborrheic dermatitis can cause hair thinning.

Hair thinning and baldness can be associated with psychological stress due to their effect on appearance.

Alopecia induced by cancer chemotherapy has been reported to cause changes in self-concept and body image.

Infectious causes include:

Dissecting cellulitis

Fungal infections


Secondary syphilis

Demodex folliculorum, a microscopic mite.

Demodex folliculorum feeds on the sebum produced by the sebaceous glands, denies hair essential nutrients and can cause thinning.

Temporary or permanent hair loss can be caused by several medications: antihypertensives,, diabetic, heart meds, cholesterol and endocrine.

Drugs that affect hormone balance can have a pronounced effect: including the contraceptives, hormone replacement therapy, steroids and acne medications.

Mycotic infection agents can cause hair loss.

Side effects from drugs include chemotherapy, anabolic steroids, and birth control pills.

Trauma due to traction can cause hair loss most commonly found in people with ponytails or cornrows who pull on their hair with excessive force.

Rigorous brushing and heat styling, rough scalp massage can damage the hair cuticle, and cause individual strands to become weak and break off, reducing overall hair volume.

Frictional alopecia refers to hair loss caused by rubbing of the hair or follicles, and is most common around the ankles of men from socks.

Trichotillomania is the loss of hair caused by compulsive pulling and bending of the hairs.

Telogen effluvium is hair loss related to trauma, childbirth, major surgery, poisoning, and severe stress.

With telogen effluvium large numbers of hair enter the resting phase at the same time, causing shedding and subsequent thinning.

Telogen effluvium is also a manifestation of chemotherapy targeting dividing cancer cells, affecting hair’s growth phase with the result that almost 90% of hairs fall out soon after chemotherapy starts.

Radiation to the scalp, can cause baldness of the irradiated areas.

Hair loss often follows childbirth.

During pregnancy the hair is actually thicker owing to increased circulating estrogens.

Approximately three months after giving birth estrogen levels drop and hair loss occurs, often particularly noticeably around the hairline and temple area.

Post delivery hair loss grows back normally and treatment is not indicated.

Similarly, this situation occurs in women taking the fertility-stimulating drug clomiphene.

Alopecia areata

Alopecia Ariana is an autoimmune disease characterized by rapid hair loss in the scalp, eyebrows, and eyelashes.

Alopecia areata is a transient problem for many people,as small patches of hair loss recover spontaneously within a few months.

About 1/3 of patients with scalp hair loss of 25 to 50% have active patchy disease at long-term follow up.

A third of patients with alopecia areata progress to alopecia totalis or alopecia universalis, from which recovery is rare.

Alopecia areata is associated with impaired health related quality of life, with emotional and psychological disabilities and anxiety, depression, absenteeism, and unemployment more prevalent than in controls.

Alopecia areata is an autoimmune disorder can result in hair loss ranging from just one location to every hair on the entire body.

Current treatments include glucocorticoids given topically, intralesionally, and systemically, other immunosuppressive agents, and contact immunotherapy have had variable efficacy.

Oral barcitinib, a JAK1, and 2 inhibotir is superior to placebo we respect to hair regrowve at 36 weeks.

Localized or diffuse hair loss may also occur in cicatricial alopecia such as lupus erythematosus, lichen plano pilaris, folliculitis decalvans, central centrifugal cicatricial alopecia, and postmenopausal frontal fibrosing alopecia.

Tumors and skin outgrowths can cause localized baldness as with sebaceous nevus, basal cell carcinoma, and squamous cell carcinoma.

Hypothyroidism can cause hair loss, typically frontal, which is particularly associated with thinning of the outer third of the eyebrows.

Hyperthyroidism can also cause hair loss, which is parietal rather than frontal.

Temporary loss of hair can occur in areas where sebaceous cysts are present.

Congenital triangular alopecia:

A triangular, or oval patch of hair loss in the temple area of the scalp that occurs mostly in young children, is known as congenital triangular alopecia.

Congenital triangular alopecia site contains vellus hair follicles or no hair follicles at all, but it does not expand.

Congenital triangular alopecia cause is unknown, and is a permanent condition, with out other effects on the affected patient.

Involutional alopecia refers to gradual thinning of hair with age is a natural condition.

Involutional alopecia is caused by an increasing number of hair follicles switching from the growth, or anagen, phase into a resting phase, or telogen phase, so that remaining hairs become shorter and fewer in number.

Air and water pollutants, environmental toxins, styling products and excessive amounts of sebum have the potential to build up on the scalp, and can block hair follicles and cause their deterioration and consequent miniaturization of hair.

Scalp debris can also physically restrict hair growth or damage the hair cuticle.

Scalp debris leading to hair that is weakened and easily broken off.

Hair follicle growth occurs in cycles.

Each hair follicle growth cycle consists of a long growing phase, anagen, a short transitional phase, catagen, and a short resting phase telogen.

Anagen effluvium involves a rapid loss of hair. 

This usually happens because of radiation treatment or chemotherapy.

Hair will usually regrow after the treatment stops.

Telogen effluvium

Telogen effluvium is a type of sudden hair loss that results from emotional or physical shock, like a traumatic event, period of extreme stress, or a serious illness.

It can also happen because of hormonal changes, like those that happen in:




Polycystic Ovary Syndrome (PCOS)

Other potential causes of telogen effluvium include:

malnutrition including vitamin or mineral deficiency

certain endocrine disorders

starting or stopping hormonal birth control

post surgery as a result of the anesthesia

acute illnesses or severe infections like COVID-19

Several types of medications can also cause it, including:



oral retinoids


thyroid medications

This type of hair loss typically resolves on its own once the underlying cause is addressed.

Tinea capitis, also called ringworm of the scalp, is a fungal infection that can affect the scalp and hair shaft. 

It causes small bald patches that are scaly and itchy. 

Other symptoms include: brittle hair that breaks easily, scalp tenderness, scaly patches of skin that look grey or red.

It’s treatable with antifungal medication.

Following the resting phase, the hair falls out, exogen, and a new hair starts growing in the follicle beginning the cycle again.

Normally, about 40 hairs reach the end of their resting phase each day and fall out.

When more than 100 hairs fall out per day, clinical hair loss, may occur.

A disruption of the growing phase causes abnormal loss of anagen hairs referred to as anagen effluvium.

The pull test helps to evaluate diffuse scalp hair loss.

The pull test is performed by grasping the base of 48 and 50 years and pulling away from the scale will be positive in diffuse hair loss, this large in greater than four telogen hairs identified by their club shape bulbs in patients with telogen effluvium.
The pull test refers to the gentle traction on a group of hairs, about 40–60 in number, on three different areas of the scalp. 

Traction alopecia results from too much pressure and tension on the hair, often from wearing it in tight styles, like braids, ponytails, or buns.

With the pull test the number of extracted hairs is counted and examined under a microscope.

Fewer than three hairs per area should come out with each pull. If more than ten hairs are obtained, the pull test is considered positive.

The pluck test refers to pulling hair out “by the roots”.

The root of the plucked hair is examined under a microscope to determine the phase of growth.

It is used to diagnose a defect of telogen, anagen, or systemic disease.

Telogen hairs have tiny bulbs without sheaths at their roots.

Telogen effluvium shows an increased percentage of hairs upon examination.

Anagen hairs have sheaths attached to their roots.

Anagen effluvium shows a decrease in telogen-phase hairs and an increased number of broken hairs.

If a hair count is >100/day, it is considered abnormal except after shampooing, where hair counts will be up to 250 and be normal.

Trichoscopy is a noninvasive test performed with the use of a handheld dermoscope or a video dermoscope.

Trichoscopy allows for a differential diagnosis of hair loss in most cases.

Two types of identification tests for female pattern baldness exist: the Ludwig Scale and the Savin Scale, which track the progress of diffused thinning, which typically begins on the crown of the head behind the hairline, and becomes gradually more pronounced. 

For male pattern baldness, the Hamilton–Norwood scale tracks the receding hairline and/or a thinning crown, to a horseshoe-shaped ring of hair around the head and on to total baldness.

Three medications have evidence to support their use in male pattern hair loss: minoxidil, finasteride, and dutasteride.

These drugs typically work better to prevent further hair loss, than to regrow lost hair.

Minoxidil is a nonprescription medication approved for male pattern baldness and alopecia areata.

In its liquid or foam form, it is rubbed into the scalp twice a day.

It is not effective for other causes of hair loss.

Hair regrowth can take 1 to 6 months to begin.

Treatment must be continued indefinitely.

Most frequent side effects are mild scalp irritation, allergic contact dermatitis, and unwanted hair in other parts of the body.

Finasteride can be used in male-pattern hair loss.

Finasteride is not indicated for women and is not recommended in pregnant women.

Finasteride is effective starting within 6 weeks of treatment, and causes an increase in hair retention, the weight of hair, and some increase in regrowth.

Finasteride works by inhibiting 5 alpha-reductase to reduce levels of DHT in the scalp.

Side effects occur in about 2% of males on finasteride and include decreased sex drive, erectile dysfunction, and ejaculatory dysfunction.

However, the drug’s efficacy is unclear in females, and some doctors advise females who are looking to get pregnant against taking it because the drug can cause a male fetus to develop ambiguous genitalia.

Treatment should be continued as long as positive results occur.

Once treatment is stopped, hair loss resumes.

Corticosteroids injections into the scalp can be used to treat alopecia areata.

Hormonal agent-oral contraceptives or antiandrogens such as spironolactone and flutamide can be used for female-pattern hair loss associated with hyperandrogenemia.

Hair transplantation is usually carried out under local anaesthetic, moving healthy hair from the back and sides of the head to areas of thinning.

Hair transplantation takes between four and eight hours.

Transplanted hair falls out within a few weeks, but regrows permanently within months.

Hair transplants, takes tiny plugs of skin, each which contains a few hairs, and implants the plugs into bald sections.

Other options such as follicle transplants, scalp flaps, and hair loss reduction, are available.

Anti-inflammatory medications are considered, if hair loss seems related to an autoimmune condition.

Wigs are an alternative to medical and surgical treatment.

Hypothermia caps may be useful to prevent hair loss during some kinds of chemotherapy.

Dietary supplements are not typically recommended, and only one small trial of saw palmetto which shows tentative benefit in those with mild to moderate androgenetic alopecia.

There has been speculation about a connection between early-onset male patterned hair loss and heart disease, but review of articles from 1954 to 1999 found no conclusive connection.

Vertex baldness, unlike frontal baldness is associated with an increased risk of coronary heart disease and the relationship depends upon the severity of baldness.

A study controlled for age and family history, and found statistically significant positive associations between moderate or severe male pattern hairloss and smoking status in Asian men.

Hair follicle renewal is maintained by the stem cells associated with each follicle.

Aging of the hair follicle appears to be related to cellular response to the DNA damage that accumulates in renewing stem cells during aging.

The response to DNA damage involves the proteolysis of type XVII collagen by neutrophil elastase.

Proteolysis of collagen leads to elimination of the damaged cells and then to terminal hair follicle miniaturization.

Hair transplant surgery works well for people with inherited baldness since they typically lose hair on the top of the head. 

Products or tools that can affect hair loss include:

blow dryers

heated combs

hair straighteners

coloring products

bleaching agents



Vitamins that may promote hair growth include:

B vitamins, specifically riboflavin, biotin, folate, and vitamin B12


vitamin C

vitamin D

An increased risk of hair loss is connected with certain illnesses:

polycystic ovary syndrome (PCOS)

scalp psoriasis

sexually transmitted infections, such as syphilis

thyroid disease

Hair loss can also be a side effect of some medications, especially chemotherapy medications to treat cancers.

Some hair loss causes cannot be reversed: too-tight hairstyles, damaged hair follicles from chemicals applied to the hair, and damages caused by certain autoimmune diseases.

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