Through the number of hair loss, hair density, accompanying symptoms, and examination in the hospital, you can determine whether it is normal hair loss or alopecia. 1. Number of hairs: Due to the metabolism of human body, a small amount of hairs will fall out every day, and under normal circumstances, the hairs fall out for 50~100 per day. If the hair loss is more, such as more than 100, consider that it is related to alopecia. 2. Hair density: It is recommended to observe or take photos to see whether the hair is decreasing and whether the hairline is moving back. If the hair is gradually decreasing, the scalp is bare and the hairline is moving back, it can be initially judged as alopecia areata. 3. Accompanying Symptoms: Normal hair fall usually has no trace and is not accompanied by other uncomfortable symptoms. If the hair becomes thin, soft, dandruff increases, dry hair, easy to break, consider that it is related to hair loss. 4. Go to the hospital for examination: If necessary, go to the dermatology department of the hospital for examination, the doctor will carry out dermoscopy, which can initially determine whether it is alopecia areata. If you have progressive hair loss, it is recommended that you go to the dermatology department of the hospital and have a dermoscopic examination, which can determine whether it is alopecia areata or not.