There is no simple answer to this question. There are a number of things that could be what causes health problems to the immune system. Immune system defense mechanisms can be weakened by a host of factors. Here we look at how the immune system functions and some of the issues that can lead to a compromised immune system.

The first immune system defense that bacteria and other invaders encounter is the skin. The skin contains keratin (which inhibits bacterial growth) and the sebaceous glands, from which hairs grow and sebum is secreted. Sebum is composed of fatty acids and inhibits the growth of some types of bacteria and fungi. If the skin is healthy and good health habits are practices, such as washing hands before touching the face, then many invaders can never enter the body proper.

Certain viruses, germs, bacteria and fungi are airborne, but there is an immune system defense built into the lungs and upper respiratory tract to fight them. Cilia (tiny hairs) lining the nose, throat and lungs can trap and help expel foreign bodies through coughing and sneezing. Cigarette smoking can be what causes health problems to the immune system, because the nicotine paralyzes these tiny hairs allowing bacteria or viruses to remain in the respiratory tract longer than they should. Cigarette smoking also inhibits the body's ability to absorb vitamin C and other essential nutrients. Vitamin C plays numerous roles in proper immune system function.

White blood cells are the primary infection fighters in the immune system defense mechanisms. Any disease, condition or chemical which affects the body's ability to produce adequate white blood cells can be what causes health problems to the immune system. Additionally lack of proper nutrition necessary for the body to produce white blood cells can lead to immune system problems.

Diseases which can lead to a compromised immune system include HIV/AIDS and a number of congenital abnormalities that relate to the lymph nodes and other portions of the immune system defense mechanisms. Treating these diseases may not always lead to the healthy function of the immune system.

In other cases, the treatment of some diseases leads to a compromised immune system. Rheumatoid arthritis, lupus, Crohn's disease and a number of other diseases are theoretically caused by a dysfunction of the immune system, in which white blood cells attack healthy disease-free cells of the body causing inflammation. Treating these diseases with immuno-suppressant drugs is what causes health problems to the immune system in some cases. These drugs limit the body's natural ability to fight infection.

Anti-cancer drugs, corticosteroids and antibiotics can all lead to a general weakening of immune system defense mechanisms. Alcohol abuse, drug abuse, exposure to radiation and/or environmental toxins can all be what causes health problems to the immune system. If health problems of the immune system is defined as a weakened immune system response, then any of the things mentioned here could be the cause. Additionally, studies have shown that stress, depression, age, lack of sleep, lack of exercise or excessive exercise can all impair the body's natural ability to defend itself. There are natural products which have been proven to boost the immune system, even in cases where the immune system defense mechanisms have been compromised by any of the problems listed here. These products may contain beta glucans, andrographis paniculata or a variety of other ingredients.