Causes of Teen Hair Loss

A condition where the body’s immune system attacks hair follicles—the tiny openings where hair grows. This causes sudden, patchy hair loss, usually in small round spots. It can happen anywhere on the scalp or other parts of the body.

Major stress, illness, or injury can interrupt the normal cycle of hair growth. More hairs than usual stop growing and fall out, often a few months after the stressful event. This type of hair loss is usually temporary.

Caused by pulling on the hair for long periods, often from tight hairstyles like braids, ponytails, or buns. Over time, the constant tension damages hair follicles, leading to thinning or bald spots, especially around the hairline.

If your body doesn’t get enough key nutrients—like iron, zinc, or certain vitamins—your hair can become weaker and fall out more easily. For example, iron deficiency anemia can reduce the oxygen supply to hair follicles, slowing growth and causing shedding.

The thyroid is a gland that produces hormones to regulate many body functions, including hair growth. If it makes too much hormone (hyperthyroidism) or too little (hypothyroidism), it can disrupt the hair growth cycle and cause overall thinning or increased shedding.