Resting alopecia is the excessive loss of normal resting pestle hair caused by a variety of stressors. This type of hair loss most often occurs 3 to 5 months after the premature conversion of many anagen hairs to resting hairs. In general, a resting hair count of >25% of the hairs shed is diagnostic of resting alopecia, and >20% is a possible abnormality. Etiology There are many causes of resting hair loss, mainly the following: endocrine changes such as hypothyroidism, postpartum or after discontinuation of birth control pills. Nutritional factors including low or deficient intake of calories, protein, essential fatty acids, zinc, biotin and iron. Medications such as antidepressants, angiotensinase converters, antisemitics (dose-dependent), beta-blockers, lithium, oral contraceptives, retinoids, valproic acid, etc. Somatic stress conditions such as anemia, hyperthermia, allergic contact dermatitis due to hair dyeing, vitamin A augmentation secondary to renal dialysis patients, surgical procedures, and psychological stress. Clinical manifestations Clinical manifestations are diffuse hair loss, but rarely involves more than 50% of the hair. Patients find that hair loss increases when combing or washing hair, mostly temporary thinning of hair, and occasionally may involve body hair. Some patients are associated with hair pain, or depression, obsessive-compulsive personality disorders and anxiety. Resting hair loss is most common in the postpartum period. During pregnancy, hairs can stagnate in the anagen phase for a long time without entering the resting phase as normal, and during delivery, these follicles enter the resting phase at the same time, and after 3 to 5 months, the hairs fall out. Examination Histopathology: The number of hair follicles in the resting phase increases and the hair is pestle-shaped. The hairs in the resting phase of alopecia are shed from the roots, and each shed hair is visible as a depigmented hair bulb-like structure, but without a root sheath. If a 4-mm diameter borehole biopsy is done, 20 to 25 hairs are visible in a normal cross-section. If more than 12% to 15% of the terminal hair follicles are in the resting phase, it suggests that the follicles have significantly changed from the anagen phase to the resting phase. Diagnosis The number of resting hair loss can be estimated by pulling test or by asking the patient to collect and count the number of hair loss per day; a resting hair count >25% is the diagnostic criterion. Treatment There is no specific treatment for resting alopecia, the key is to find the cause and remove it. In most cases, hair loss stops on its own within 6 months to 1 year and hair can grow back. We should encourage a balanced diet, eat more black foods and nuts, appropriate psychological guidance, and can also use a combination of Chinese and Western medicine based on traditional Chinese medicine.