The causes of hair loss can broadly be divided into two types, scarring and non- scarring.

In scarring type of hair loss, hair roots and adjacent skin are permanently damaged. There are no chances of hair growing back at these sites with any medications. This type of condition can result from mechanical injury, burn, radiation and skin disease like lichen planopilaris, discoid lupus erythematosus, etc.

In non scarring type of hair loss hair roots are preserved and hair growth can be expected at bald areas. There are different reasons of non scarring type of hair loss.

ANDROGENETIC ALOPECIA (PATTERN HAIR LOSS)

Androgenetic alopecia also called a pattern hair loss is the most common cause of hair loss in which thick hairs gradually become thin and short because of the byproduct Dihydrotestosterone (DHT) of male hormone testosterone.

It is also called a pattern hair loss because hair loss follows a particular pattern. Male tends to lose hair in the front, crown and middle part of scalp but retain hair at the sides and back of the scalp. These retained hairs has the DHT resistant follicles, are often referred to as the “permanent zone”.

In case of female, there is a gradual widening of the central parting preserving the frontal hair line. Unlike male, it involves the diffuse hair thinning. Increased androgen production may be a contributing factor in female with pattern hair loss.

ALOPECIA AREATA

Alopecia areata is the conditions for hair fall in which person’s immune system attack his/her own hair follicles causing hair loss. It presents as smooth circular to oval patches of hair loss over scalp, beard, eyebrows or any other body sites.

TELOGEN EFFLUVIUM

In telogen effluvium, the abrupt transition of hair cycle from growing phase (anagen) to shedding phase (telogen) causing diffused hair loss because of the predisposing factor called stressor. If the predisposing factor is not removed, hair fall may be continuous. Below is the list of conditions that can lead to telogen effluvium.

1. Obstetric and gynecological conditions
2. Anaemia
3. Thyroid disease
4. Nutritional cause like crash diets, bulimia, protein/calorie deficiency, zinc deficiency, hypervitaminosis A or essential fatty acid deficiency.
5. Stress from surgical procedure, general anesthesia or several emotional problems.

 ANAGEN EFFLUVIUM

This is seen in cancer patients who are on anti-cancer drugs. These drugs acts on growing hair causing hair fall. It is usually reversible after stoppage of anti cancer drugs.

 TRACTION ALOPECIA

It occurs when continuous pulling force acts on hair due to tight braiding, pony tails, pigtails etc.

 TRICHOTILLOMANIA

It is a psychiatric disease where there is an irresistible desire to pull out own hair.