AGA
Alopecia
Alopecia is the medical description of the loss of hair from the head or body, sometimes to the extent of baldness. Unlike the common aesthetic depilation of body hair, alopecia tends to be involuntary and unwelcome, e.g., androgenic alopecia. However, it may also be caused by a psychological compulsion to pull out one’s own hair (trichotillomania) or the unforeseen consequences of voluntary hairstyling routines (mechanical “traction alopecia” from excessively tight ponytails or braids, or burns to the scalp from caustic hair relaxer solutions or hot hair irons).
In some cases, alopecia is an indication of an underlying medical concern, such as iron deficiency.
Alopecia Areata

Bald spots caused by Alopecia Areata
Alopecia areata (AA) is a condition affecting humans, in which hair is lost from some or all areas of the body, usually from the scalp. Because it causes bald spots on the scalp, especially in the first stages, it is sometimes called spot baldness. In 1%–2% of cases, the condition can spread to the entire scalp (Alopecia totalis) or to the entire epidermis (Alopecia universalis). Conditions resembling AA, and having a similar cause, occur also in other species
Alopecia Totalis
Alopecia Universalis
Anagen phase
Androgen receptor
The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor which is activated by binding of either of the androgenic hormones testosterone or dihydrotestosterone in the cytoplasm and then translocating into the nucleus. The androgen receptor is most closely related to the progesterone receptor, and progestins in higher dosages can block the androgen receptor.
The main function of the androgen receptor is as a DNA binding transcription factor which regulates gene expression; however, the androgen receptor has other functions as well.[6] Androgen regulated genes are critical for the development and maintenance of the male sexual phenotype.
Androgenic alopecia
Androgenic alopecia (also known as androgenetic alopecia or alopecia androgenetica) is a common form of hair loss in both female and male humans, chimpanzees, and orangutans. In male humans in particular, this condition is also commonly known as male pattern baldness. Hair is lost in a well-defined pattern, beginning above both temples. Hair also thins at the crown of the head. Often a rim of hair around the sides and rear of the head is left, or the condition may progress to complete baldness.
The pattern of hair loss in women differs from male pattern baldness. In women, the hair becomes thinner all over the head, and the hairline does not recede. Androgenic alopecia in women rarely leads to total baldness.
Baldness
Example of women affected by female pattern hair lossBaldness is the state of having no hair or lacking hair where it often grows, especially on the head. The most common form of baldness is a progressive hair thinning condition called androgenic alopecia or “male pattern baldness” that occurs in adult male humans and other species. The amount and patterns of baldness can vary greatly; it ranges from male and female pattern alopecia (androgenic alopecia, also called androgenetic alopecia or alopecia androgenetica), alopecia areata, which involves the loss of some of the hair from the head, and alopecia totalis, which involves the loss of all head hair, to the most extreme form, alopecia universalis, which involves the loss of all hair from the head and the body.
Blowdryer
Caffeine
Caffeine has been identified as a stimulator of human hair growth in vitro (in this image: coffee beans) Caffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term kaffein, a chemical compound in coffee (the German word for which is Kaffee), which in English became caffeine (and changed to Koffein in German).
Caffeine is found in varying quantities in the beans, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the bean of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Other sources include yerba mate, guarana berries, and the Yaupon Holly.
Caffeine has been identified as a stimulator of human hair growth in vitro, and reduced testosterone-induced follicle growth suppression. It has been demonstrated that the addition of caffeine to a shampoo-formulation is effective in administering caffeine to the hair follicles in the scalp. Further research must be done to evaluate the efficacy and adequate dosage of caffeine in the treatment of androgenetic alopecia.
A spray made with coffee beans is claimed to prevent age-related hair loss in women.
Catagen phase
Chemotherapy
Comb over
Dandruff
Demi-permanent hair color
Demi-permanents are much more effective at covering gray hair than semi-permanents, but less so than permanents.
DHT
Dihydrotestosterone
Dutasteride
Eumelanin
There are two different types of eumelanin. The two types are black eumelanin and brown eumelanin, with black melanin being darker than brown. Black eumelanin is mostly in non-Europeans and aged Europeans, while brown eumelanin is in mostly young Europeans.
A small amount of black eumelanin in the absence of other pigments causes grey hair. A small amount of brown eumelanin in the absence of other pigments causes yellow (blond) color hair.
FDA
Female Hair Loss
However, female hair loss has become a growing problem which according to the American Academy of Dermatology affects around 30 million women in the United States. Although hair loss in females normally occurs after the age of 50 or even later when it does not follow events like pregnancy, chronic illness, crash diets, and stress among others, it is now occurring at earlier ages with reported cases in women as young as 15 or 16.
Finasteride
Popular and FDA approved hair loss treatmentFinasteride (marketed by Merck under the trademark names Proscar and Propecia, also available under several generic names) is a synthetic antiandrogen that acts by inhibiting type II 5-alpha reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT). Finasteride was initially approved by the U.S. Food and Drug Administration (FDA) in 1992 under the brand name Proscar, a treatment for benign prostatic hyperplasia (BPH). In 1997, the FDA approved finasteride to treat male pattern baldness (MPB) under the brand name Propecia.Follicular Unit Extraction
Follicular Unit Transplantation
FUT is considered an advance over older hair transplantation procedures that used larger grafts and often produced a pluggy, unnatural look. In a properly-performed follicular unit transplant, the results will mimic the way hair grows in nature and will be undetectable as a hair transplant.
FUT
Hair
Hair, which has been grown for 5 yearsHair is a filamentous biomaterial, containing keratin, that grows from follicles found in the dermis. The human body, apart from the palms of the hands and soles of the feet, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types and hair care but hair is also an important biomaterial and the hair follicle is a well studied biological organ.
Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class. Although other non-mammals, especially insects, show filamentous outgrowths, these are not considered “hair” in the scientific sense. So-called “hairs” (trichomes) are also found on plants. The projections on arthropods such as insects and spiders are actually insect bristles, composed of a polysaccharides called chitin. There are varieties of dogs, cats, and mice bred to have little or no visible fur. In some species, hair is absent at certain stages of life. The main component of hair fiber is keratin.
Hair care
Hair care is an overall term for parts of hygiene and cosmetology involving the hair on the human head. Hair care will differ according to one’s hair type and according to various processes that can be applied to hair. All hair is not the same; indeed, hair is a manifestation of human diversity.
In this article, ‘Hair care’ is taken to mean care of hair on the human head, but mention should be made of process and services which impact hair on other parts of the body. This includes men‘s and women’s facial, pubic, and other body hair, which may be dyed, trimmed, shaved, plucked, or otherwise removed with treatments such as waxing, sugaring, and threading. These services are offered in salons, barbers, and day spas, and products are available commercially for home use. Laser hair removal and electrolysis are also available, though these are provided (in the US) by licensed professionals in medical offices or specialty spas.
Hair Color
Samples of different hair colorsParticular hair colors can be associated with ethnic groups however, due to migration and global travel, considerable variations have developed in the hair color of individuals within an ethnic group, creating a greatly increased diversity of hair color.
Hair cycle
Hair Dye
Example of shiny green hair dyeHair Dye, or Hair Color, is a chemical tool that is used to change the color of a person’s hair. Hair dye is used mostly to change gray hair, since gray hair is a sign of an advanced age. Younger people that used hair dye use it as a fashion statement or simply because they want to change their hair color. The Romans have been known to be interested in changing hair color and history revealed that they created over a hundred recipes that are made out of natural ingredients but unfortunately it could only darken hair. In Renaissance time, blonde was a popular choice because it was considered to be angelic and attractive. In 1907, Eugene Schueller, the founder of L’Oreal, created the first synthetic hair dye, but it wasn’t widely sold.Hairdryer
A blowdryer – daily equipment to dry and style hairA blowdryer or hairdryer is an electromechanical device designed to blow cool or hot air over wet or damp hair, in order to accelerate the evaporation of water particles and dry the hair. Blowdryers allow to better control the shape and style of hair, by accelerating and controlling the formation of temporary hydrogen bonds inside each strand. These hydrogen bonds are very powerful (allowing for stronger hair shaping than even the sulfur bonds formed by permanent waving products), but are temporary and extremely vulnerable to humidity. They disappear with a single washing of the hair.
Hairstyles using blowdryers usually have volume and discipline, which can be further improved by the use of styling products and hairbrushes during drying to add tension, hold and lift.
Blowdryers were invented around the end of the 19th century. The first model was created by Alexander Godefoy in his salon in France. The handheld, household hair-dryer first appeared in 1920.
Hair Follicles
Detailed view of a hair follicleA hair follicle is a part of the skin that grows hair by packing old cells together. Attached to the follicle is a sebaceous gland, a tiny sebum-producing gland found everywhere except on the palms, lips and soles of the feet. The thicker the density of the hair, the more the number of sebaceous glands that are found.
The average growth rate of healthy hair follicles on the scalp is half an inch per month.
Hair Iron
A hair iron, which is used to straighten hairA hair iron or hair tong is a tool used to change the structure of the hair using heat. There are three general kinds: curling irons, used to make the hair curly, straightening irons, used to straighten the hair, and crimping irons, used to create crimps of the desired size in the hair.Hair Restoration
Hairstyle
Hair Transplantation
Before and after image of a hair transplantHair transplantation is a surgical technique that involves moving skin containing hair follicles from one part of the body (the donor site) to bald or balding parts (the recipient site). It is primarily used to treat male pattern baldness, whereby grafts containing hair follicles that are genetically resistant to balding are transplanted to bald scalp. However, it is also used to restore eyelashes, eyebrows, and beard hair, and to fill in scars caused by accidents and surgery such as face-lifts and previous hair transplants. Hair transplantation differs from skin grafting in that grafts contain almost all of the epidermis and dermis surrounding the hair follicle, and many tiny grafts are transplanted rather than a single strip of skin.Intercytex
Keratin
Ketoconazole
Ketoconazole is very lipophilic, which leads to accumulation in fatty tissues. The less toxic and more effective triazole compounds fluconazole and itraconazole have largely replaced ketoconazole for internal use. Ketoconazole is best absorbed at highly acidic levels, so antacids or other causes of decreased stomach acid levels will lower the drug’s absorption when taken orally.
Low level laser therapy
Despite a lack of consensus over its ideal use, specific test and protocols for LLLT suggest it is effective in relieving short-term pain for rheumatoid arthritis, osteoarthritis, acute and chronic neck pain, tendinopathy, and possibly chronic joint disorders. The evidence for LLLT being useful in the treatment of low back pain, dentistry and wound healing is equivocal
Minoxidil
Rogaine -a popular and FDA approved hair loss treatmentMinoxidil (trade names Rogaine, Regaine, Avacor and Mintop among others now that Minoxidil is off patent) is a vasodilator medication known for its ability to slow or stop hair loss and promote hair regrowth. It is available over the counter for treatment of androgenic alopecia, among other baldness treatments, but measurable changes disappear within months after discontinuation of treatment.
Pheomelanin
Pityriasis simplex capilitii
Those affected by dandruff find that it can cause social or self-esteem problems. Treatment may be important for both physiological and psychological reasons.
Propecia
Rogaine
Saw palmetto
Saw Palmetto leaves
Saw palmetto extract is an extract of the fruit of Serenoa repens. It is rich in fatty acids and phytosterols. It has been used in traditional, eclectic, and alternative medicine for a variety of indications, most notably benign prostatic hyperplasia.
Saw Palmetto leaves have been indicated to help fighting hair loss. However, efficacy has been discussed controversial by the scientific community
Seborrhoeic dermatitis
Semi-permanent hair color
Semi-permanent hair dye has smaller molecules than temporary dyes, and is therefore able to partially penetrate the hair shaft. For this reason, the color will survive repeated washing, typically 4-5 shampoos. Semi-permanents contain no, or very low levels of developer, peroxide or ammonia, and are therefore safer for damaged or fragile hair. However, semi-permanents may still contain the toxic compound P-Phenylenediamine or other such ingredients.
The final color of each strand of hair will depend on its original color and porosity, so there will be subtle variations in shade across the whole head. This gives a more natural result than the solid, allover color of a permanent dye. However, it also means that gray or white hairs will not dye to the same shade as the rest of the hair. If there are only a few gray/white hairs, the effect will usually be enough for them to blend in, but as the gray spreads, there will come a point where it will not be disguised as well..
In this case, the move to permanent color can sometimes be delayed by using the semi-permanent as a base and adding highlights.
Semi-permanent color cannot lighten the hair.
Skin grafting
Skin grafting is a type of medical grafting involving the transplantation of skin. The transplanted tissue is called a skin graft.
Skin grafting is often used to treat:
* Extensive wounding or trauma
* Burns
* Areas of extensive skin loss due to infection such as necrotizing fasciitis or purpura fulminans
* Specific surgeries that may require skin grafts for healing to occur
Split ends
Telogen Effluvium
Massive hair loss caused by Telogen EffluviumTelogen effluvium is characterized by massive hair loss as a result of early entry of hairs into the telogen phase. Emotional or physiological stressful events may result in an alteration of the normal hair cycle. It may be due to a variety of causes, eating disorders, fever, childbirth, chronic illness, major surgery, anemia, severe emotional disorders, crash diets, hypothyroidism, and drugs.Telogen phase
Testosterone
A structure of TestosteroneTestosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.
In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle and bone mass and hair growth. In addition, testosterone is essential for health and well-being as well as the prevention of osteoporosis
Temporary hair color
Temporary hair color is available as rinses, shampoos, gels, sprays, and foams among others. This type of hair color is typically brighter and more vibrant than semi-permanent and permanent hair color. Temporary color is most often used to color hair for special occasions and is often used in unusual shades for events, parties, costumes, and Halloween.
The pigment molecules in temporary hair color are large and cannot penetrate the cuticle layer. Instead, the color particles remain absorbed (closely adherent) to the hair shaft and are easily removed with a single shampooing.
However, even temporary hair color can persist if the user’s hair is excessively dry or damaged, allowing for migration of the pigments to the interior of the hair shaft.
It also holds color to about 6 to 7 washes.
Tinea Capitis
An image of what Tinea Capitis look likeTinea capitis (also known as “Herpes tonsurans”, “Ringworm of the hair,” “Ringworm of the scalp,” “Scalp ringworm”, and “Tinea tonsurans”) is a superficial fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermatophytes in the Trichophyton and Microsporum genera that invade the hair shaft. The clinical presentation is typically a single or multiple patches of hair loss, sometimes with a ‘black dot’ pattern (often with broken-off hairs), that may be accompanied by inflammation, scaling, pustules, and itching. Uncommon in adults, tinea capitis is predominantly seen in pre-pubertal children, more often in boys than girls.
Over eight species of dermatophytes are commonly associated with tinea capitis. Cases of Trichophyton infection predominate from Central America to the United States and in parts of Western Europe. Infections due to Microsporum species are mainly seen in South America, Southern and Central Europe, Africa and the Middle East. The disease is infectious and can be transmitted by humans, animals, or objects that harbor the fungus. Carrier states also exist where the fungus is present on the scalp but there are no clinical signs or symptoms. Treatment of tinea capitis requires an oral antifungal agent; griseofulvin is the most commonly used drug, but other newer antimycotic drugs, such as terbinafine, itraconazole, and fluconazole have started to gain acceptance.
Toupee
Toupees that men use to cover their balding headA toupée (pronounced too-pay) is a hairpiece or partial wig of natural or synthetic hair worn to cover partial baldness or for theatrical purposes. While toupées and hairpieces are typically associated with male wearers, some women also use hairpieces to lengthen existing hair, or cover partially exposed scalp. The desire to wear hairpieces is a response to a long-standing bias against balding that crosses cultures, dating to at least 3100 BC. Toupée manufacturers’ financial results indicate that toupée use is an overall decline, due in part to alternative methods for dealing with baldness, and to greater cultural acceptance of the condition.Traction Alopecia
Traction alopecia is a form of alopecia, or gradual hair loss, caused primarily by pulling force being applied to the hair. This commonly results from the sufferer frequently wearing his/her hair in a particularly tight ponytail, pigtails, or braids. It is also seen occasionally in long-haired toy dogs whose owners use barrettes to keep hair out of the dogs’ faces.
Traction alopecia is a substantial risk in hair weaves, which can be worn either to conceal hair loss, or purely for cosmetic purposes. The former, such as those sold by Hair Club in the United States, involve creating a braid around the head below the existing hairline, to which an extended-wear hairpiece, or wig, is attached. Since the hair of the braid is still growing, it requires frequent maintenance, which involves the hairpiece being removed, the natural hair braided again, and the piece snugly reattached. The tight braiding and snug hairpiece cause tension on the hair that is already at risk for falling out.
Trichoptilosis
Trichoptilosis is the “splitting of hairs at the ends”, according to Dorland’s Pocket Medical Dictionary. Often referred to as “split ends”. Comes from the Greek root “tricho” meaning hair and “ptilosis” meaning “falling out of the eyelashes”. It is also called “schizotrichia”.
A split end is when the hair-shaft splits or flays due to excessive heat and misuse.
Trichotillomania
Result of too much pulling of hairTrichotillomania (TTM, also known as trichotillosis, or more commonly as trich) is defined as “hair loss from a patient’s repetitive self-pulling of hair” and is characterized by the repeated urge to pull out scalp hair, eyelashes, facial hair, nose hair, pubic hair, eyebrows or other body hair, sometimes resulting in noticeable bald patches. Trichotillomania is classified in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) as an impulse control disorder, but there are questions about how it should be classified. It may seem, at times, to resemble a habit, an addiction, a tic disorder or an obsessive–compulsive disorder.
The disorder “leads to noticeable hair loss, distress, and social or functional impairment”, and is “often chronic and difficult to treat”.
Trichotillomania may be present in infants, but the peak age of onset is 9 to 13. Depression or stress can trigger the trich. Due to social implications the disorder is often unreported and it is difficult to predict accurately prevalence of trichotillomania; the lifetime prevalence of trich is estimated to be between 0.6% (overall) and 1.5% (in males) to 3.4% (in females).
The name, coined by French dermatologist François Henri Hallopeau, derives from the Greek: trich- (hair), till(en) (to pull), and mania (“an abnormal love for a specific object, place, or action”).
U.S. Food and Drug Administration
The FDA also enforces other laws, notably Section 361 of the Public Health Service Act and associated regulations, many of which are not directly related to food or drugs. These include sanitation requirements on interstate travel and control of disease on products ranging from certain household pets to sperm donation for assisted reproduction.
Vellus hair
Vellus hair is most easily observed on children and adult women, as they generally have less terminal hair to obscure it. Vellus hair is not lanugo hair. Lanugo hair is a much thicker type of hair that, in human forms, normally grows only on fetuses.
Vellus hair is differentiated from the more visible terminal or androgenic hair, which develops only during and after puberty, usually to a greater extent on men than it does on women.
Wig
Wigs commonly used by women either for medical or aesthetic purposesA wig is a head of hair made from horsehair, human hair, wool, feathers, buffalo hair, or synthetic materials which is worn on the head for fashion or various other aesthetic and stylistic reasons, including cultural and religious observance. The industry choice, however, is yak hair, which is not only inexpensive, but close in consistency and appearance to human hair as well. The word wig is short for periwig and first appeared in the English language around 1675.
Some people wear wigs to disguise the fact that they are bald; a wig may be used as a less intrusive and less expensive alternative to therapies for restoring hair. Wigs may also be used as a cosmetic accessory, sometimes in a religious context. Actors, on the other hand often wear costume wigs in order to better portray a character.

