Usually scalp hair is pulled, though eyebrows, eyelashes, or pubic hair may be involved. It is relatively common, affecting about 1 out of every 100 people in the US population. Many people, however, will have recurrent battles with this condition. In this form of hair loss, rather than just shutting down the hair follicle, a chemical actually kills the hair follicle and anagen hair. The most common example of this are the effects of drugs used to treat cancer.
Chemotherapy is medicine that's injected into the body to kill cancer cells.
One of the side effects is the poisoning of the hair follicle. Other drugs also can cause hair loss. Many medicines used to treat even common diseases can cause hair loss. Most do so by unknown mechanisms, and most of the drugs known to do this only cause hair loss in a small minority of patients. Click here for a list of the medications that are known to cause hair loss in a small percentage of patients.