Telogen effluvium, hair loss caused by pregnancy, major surgery, severe stress or drastic weight loss, can cause individuals to lose handfuls of hair at the peak of the disorder. Hereditary hair loss known as androgenetic alopecia is the most common reason for hair loss, according to Prevention Magazine. Hereditary hair loss may begin as soon as the early twenties. Hypothyroidism can lead to hair loss as well. Too little thyroid hormone leads to brittle hair, thin skin and nails that break easily.
Lupus can cause hair loss and result in a rash on the scalp, explains Prevention Magazine. People who do not get enough iron in their diet, may suffer from iron deficiency anemia that causes fatigue and hair loss. In women, polycystic ovarian syndrome is a major cause of hair loss because the hormonal imbalance disturbs the natural cycle of hair growth. The skin condition seborrheic dermatitis may cause hair loss if the scales and rash impede proper hair growth. Lastly, alopecia areata, an autoimmune disease that causes the immune system to attack the follicles causes severe hair loss.