As an adult, you've no doubt experienced blackheads often seen in your facial area, particularly the nose. Blackheads are caused by excess oil accumulating in your skin pores. And they can be cleaned up with simple face washing or blackhead strips that you can buy from local stores.

The same principles can cause (hopefully temporary) thinning hair. Good thing is it's not necessarily hair loss. Your thinning hair could simply be a shampoo, gel, or conditioner that you've been using for a long time and it's blocking up your hair follicles.

Of course, there are other causes of thinning hair, but now you can eliminate one type just on your own.

My Supercuts girl recommends the use of water-based shampoo over that of oil-based shampoos. Water soluble hair products are less of a threat to hair follicles than oil-based products.

Below are 3 more possible causes of thinning hair for women and men that you may have overlooked:

Poor Circulation

Thinning har can be caused by poor blood circulation.  Nourishment is important to hair just like any other parts of the body.  Specifically, hair follicles need nutrients such as oxygen and vitamin C to grow healthy hair.  These nutrients are delivered to the follicles through your blood and if not enough blood is reaching the scalp, thinning hair may occur.

Immune System Disorder

Alopecia areata is a rare form of hair loss caused by an immune system disorder.  Most of the time, the symptons are patchy bald spots, but some conditions can cause complete loss of hair. Some sources say that the immune system disorder adversely affects hair follicles on the scalp and other part of the body preventing them from growing hair.  Alopecia areata is treatable and can be reversible if caught on time.

dHT

Men and women both have testosterone in their body.  dHT is a natural byproduct of testosterone and it has been observed to adversely affect hair follicles by shrinking them.  When hair follicles are damaged to a point where they can no longer grow hair, pattern baldness occurs. 

But, such observations have been made only on subjects with sensitivity to dHT.  Apparently, genes have a lot to say on whether or not thinning hair occurs on women and men.