Common Causes of Hair Loss 
Although many people do not have visible hair loss, hair loss is a  natural daily occurrence. Approximately 50 to 150 hairs are lost each day, but most hair regenerates because the hair follicle remains intact.
If the follicles shrink due to heredity, hormones, stress, infection, certain prescription medication, illness,
nutritional deficiency or age, the hair is not restored. When shedding significantly surpasses hair growth,
baldness occurs.
• Male/female Pattern Baldness (Alopecia Androgenetica)
The most common cause of hair loss is the genetically inherited condition alopecia androgenetica
 - a hormone-related form of hair loss. In men it usually begins at the forehead or on the top of the
 head  and progresses to the familiar horseshoe-shaped fringe of hair. In women in results in  generalised thinning. 
It is more common for men - in whom it is known as male-pattern baldness - but it is a big problem for women too (female-pattern baldness), affecting as many as one in three between the ages of 20 and 60.
This type of hair loss can be inherited from either parent and often skips a generation, making it difficult to predict who is likely to be affected.
Autoimmune diseases  
Autoimmune diseases can cause problems that range from patchy hair loss (alopecia areata) to the loss of every single hair on the body (alopecia universalis) but fortunately these tend to be comparatively rare.
Localised scalp problems
Localised scalp problems, including severe fungal infections, may be a cause but are generally easy to spot and treat.
• Iron eficiency and thyroid problems
The two most commonly overlooked causes, particularly in women, are iron deficiency and thyroid problems - both can be confirmed using blood tests and are easy to correct. Hair loss in women also often tends to accelerate after the menopause - and may be slowed with HRT.
• Alopecia Areata
Alopecia Areata is a type of hair loss which can affect individuals of any age. This usually results in hair falling out and leaving round coin sized smooth patches on the head. In rare cases there may be a total loss of hair.

Although the cause of Alopecia Areata is not clear, in time the hair usually grows back by itself. Hair loss caused by Alopecia Areata can often be successfully treated with the help of a dermatologists.

• Traction Alopecia
In this case the individual he person pulls their hair out during poor cosmetic grooming practices.
• Illness
Severe infection, flu or a high fever can be a cause hair loss. After a bout of illness, for several weeks afterwards, a significant amount of  hair may continue to falling out. Hair loss of this nature usually corrects itself.
• Medication
Some medications can also lead to women's hair loss. For example, prescription drugs used for arthritis, blood thinning, depression, gout, heart problems or high blood pressure may cause hair loss. High doses of vitamin A have also been associated with female hair loss.
• Dietary Protein
Inadequate protein in an individuals diet can be a cause hair loss. Hair loss can be easily reversed by ensuring you eat the correct levels of protein in your diet.