Men are most commonly affected by this type of hair loss, but women can get it too, usually after menopause.
Androgenic Alopecia
This is when hair loss may come and go. It occurs mainly in young people (teenagers and young adults) and is thought to be caused by a problem with the immune system.
Telogen Effluvium
This is hair thinning, rather than hair loss. It is caused by stress or by an adverse reaction to medication. It usually corrects itself.
Scarring Alopecia
This is when scarring of the scalp destroys the hair follicles. Without follicles, hair cannot grow. This can occur as a result of various medical conditions, for instance, shingles.
Hair loss can also be caused by chemotherapy.
Treatments for Hair Loss
Your treatment will depend on the type of alopecia you have. If you have androgenic alopecia, you may be given a hormone blocking medication called finasteride.
https://www.empowher.com/hair-loss/content/hair-loss-all-about-alopecia