Hair loss prevention if very important for a person who is losing their hair.  Any hair that can be kept is going to mean that much more coverage on top.  There are several reasons that a person's hair falls out and thus there are several things that can be done to alleviate this hair loss.

One major cause of hair loss is stress to the body.  Hair loss due to stress to the body's systems can result from many causes including major surgery, high fever, infection, or stress factors in life.  Generally, with medical causes hair loss results a few weeks after the condition manifests itself but it is not long lasting. The hair will shed and then start regrowing again once the medical problems have been resolved. 

Stress can be a big factor in hair loss because the body actually goes into a survival mode if it is experiencing chemical changes caused by stress hormones.  Every person's body deals with stress differently.  Some people overeat, some people undereat, and some people develop other stress related symptoms.  If you are experiencing hair loss and there are major stressers in your life the best thing to do is to try and either minimize the stress or develop a plan for dealing with it.  Stress can have a very detrimental effect on not only your hair growth but also other systems in your body including the cardio vascular and immune systems.

Another major cause of hair loss can be nutrition.  People who deprive themselves of protein can see dramatic hair loss.  Hair is primarily constructed from protein and if you are not ingesting enough you body will start to limit hair growth and health in order to use the existing protein for more mission critical systems.  Generally, a diet must be very low in protein content in order for this to occur but it is observable in people who start a strict vegetarian diet without ensuring that they receive the necessary nutrients.  Be sure if you decide to limit animal products that you understand how to get all the necessary dietary elements that may be missing.

Vitamins are also important for proper hair growth.  In particular Biotin or Vitamin H also known as Vitamin B7 is important for proper hair growth.  Once a person has the normal level of Biotin any additional ingestion does not seem to help in hair regrowth despite what is reported on some web sites.

Most men, and some women, will experience hair loss started at the the front top of the head and progressing to the back and down the sides as they age.  This is an inherited condition know as androgenic alopecia which is normally referred to as Male Pattern Baldness.  In these people a hormone known as DHT actually bonds with the hair follicles resulting in a loss of blood supply which causes the hair to fall out.  Once these follicles die there is not much that can be done to get them growing again.

Two drugs have been accepted by the US FDA as treatments for this condition.  Finasteride, which is for men only because of potential side effects, and minoxidil which is a topical solution that can be used by both men and women.  Both of these have shown limited success with only partial hair regrowth.