Hair normally follows a predictable pattern of growth. There is about a centimeter worth of growth every month for 2 to 6 years followed by a few months of no growth, and then the hair falling out and the cycle repeating. Sometimes, however, this pattern is interrupted and excessive hair loss occurs, leading to embarrassment and stress.
Pattern Baldness
Androgenetic alopecia, more commonly known as pattern baldness, can occur in men as male pattern baldness and in women as female pattern baldness, as explained by Genetic Home Reference. This disorder tends to run in families, although not everyone in a given family will develop it, since there are some environmental factors involved. Pattern baldness typically develops over time in a characteristic pattern, which differs in men and women, but can lead to total baldness after many years.
Hormonal Changes
Hormones play an important role in the growth of hair, so when hormones are out of whack, hair loss can occur, according to the American Academy of Family Physicians. Overactive or underactive thyroid can be a cause of excessive hair loss.
The sudden drop of pregnancy hormones after the birth of a baby can also lead to large amounts of hair falling out a few months after giving birth. The hormonal changes that take place during menopause may also induce excessive hair loss.
Stress, Illness and Disease
Stress or illness can cause a temporary bout of excessive hair loss. Diseases such as lupus and diabetes may also lead the body to shed large amounts of hair and the shedding will often persist as long as the disease remains untreated.
Chemotherapy
Cancer patients often experience excessive hair loss during a course of chemotherapy treatment. This type of hair loss may reverse itself after chemotherapy is complete, but hair often grows back thinner than before treatment, according to the Mayo Clinic.
Medication
Anticoagulants, also known as blood thinners, can lead to hair loss. High blood pressure medication, drugs for gout and medicine for heart disease also may cause hair to fall out in large amounts. Birth control pills and antidepressants could include hair loss as a side effect. Excessive intake of vitamin A could also contribute to thinning hair.
Infections
A common cause of excessive hair loss in children is a fungal infection called ringworm, according to the Nemours Foundation. These scalp infections can be treated with antifungal medicines, which will usually completely cure the problem and end excessive hair loss.
Hair Mistreatment
Physical causes of excessive hair loss can include certain hair treatments such as perms and hot oil treatments. Excessive use of tight hair rollers or styling hair in a way that puts a lot of pressure on the hair follicles can cause scars to develop on the scalp that prevent hair from growing properly. Excessive loss of hair can result from this type of damage.
