There are many types of hair loss. There are many factors which could trigger Hair loss, including genetic factors, aging, local skin conditions, diseases that affect the body generally, and use of certain medications, like anti-cancer drugs or radiation thereapy. The most common types of hair loss are telogen effluvium, alopecia areata, ringworm, scarring alopecia, and hair loss due to cosmetic overprocessing. Several hundred diseases have hair loss as a primary symptom. While androgenetic alopecia (male or female pattern baldness) is by far the most common form of hair loss, dermatologists also see many people with other forms of alopecia.
Alopecia Areata: Alopecia Areata causes coin-sized bald patches on the scalp or beard. Rarely, all body hair may be lost. In most of alopecia cases, the hair usually grows back in several months, except in people with widespread hair loss, for whom re-growth is unlikely (or other parts of the body). Scientists are not sure what causes alopecia areata. It is probably caused by a combination of factors including genetic predisposition, predisposition to allergy, immune and autoimmune system responses, and emotional stress. There are three types of Alopecia Areata - Alopecia Areata, Alopecia Totalis & Alopecia Universalis. Alopecia Areata is mild patchy hair loss on the scalp or beard area. Alopecia Totalis is the loss of all scalp hair while Alopecia Universalis is the loss of scalp and all body hair.
Male Pattern Hair Loss: The most common type of hair loss in men, male pattern hair loss is caused by genetic pre-disposition and can affect male at any age after puberty. With male pattern hair loss, the hair begins to thin at the temples and at the crown. As time goes on, the hair at the temples recedes further, leaving a central spur of hair at the front, and an increasing bald spot at the crown. Eventually the areas of hair loss at the front and crown meet, and the top of the head becomes increasingly bald. Eventually all that remains is a border of hair around the side and back of the head. High Levels of DHT shorten the Hair Growth Phase. The hair roots receive nutrients from blood vessels which contain blood cells and a hormone called testosterone. Testosterone is converted to another hormone called dihydrotestosterone (DHT) by the actions of enzyme called 5 alpha reductase. When high levels of DHT are present in the scalps of men genetically disposed to male pattern hair loss, the anagen growth phase is shortened so the hair is shorter when it stops growing and over the life cycle of a few hair the hair get progressively shorter and shorter.
Other most common reasons for temporary hair loss are:
Severe Emotional Stress
Starting or Stopping Birth Control Pills