Hormonal Imbalance You may lose hair when you have polycystic ovary syndrome (PCOS). That's a women's health condition that affects your hormone levels. PCOS can lead to hirsutism -- when women sprout a lot of hair in places they normally wouldn't. You may notice hair on your face, chest, or chin. Extra androgens, sometimes called male hormones, cause this. Your doctor can help treat your PCOS. Autoimmune Disorder With alopecia areata, hair may get thin or stop growing. That's because your immune system attacks hair follicles, making it hard for hair to grow. You may get bald patches on your head or other body parts. You might lose your eyebrows or eyelashes. Sometimes, all your body hair falls out. That's called alopecia universalis. Medicine may regrow hair. And since your follicles still work, your hair might grow back when the condition isn't active. Thyroid Condition Talk to a doctor if your hair loss comes with fatigue, muscle weakness, weight loss or ga...