Isotretinoin is a first-generation retinoic acid drug, also known as 13-cis retinoic acid, which has the effects of shrinking sebaceous gland tissue, inhibiting sebaceous gland activity, reducing sebaceous gland secretion, reducing epithelial cell keratinization and reducing the number of Propionibacterium acnes, etc. It is used for the treatment of coalescent acne, nodular cystic acne and violaceous acne with remarkable efficacy and is popular among patients. Despite the significant efficacy of isotretinoin in the treatment of severe acne, its adverse effects are more frequent and deserve attention. The adverse reactions of isotretinoin in clinical practice are mainly in the following six areas. 1. Adverse reactions of skin mucosa This is the most common adverse reaction of oral isotretinoin, and the larger the oral dose, the higher the incidence of adverse reactions. Lipitis is the most common, the incidence of 100%, manifested as dry, cracked, peeling, bleeding of the mucous membrane of the mouth and lips, similar to exfoliative dermatitis, nearly 30% to 50% of patients with dry nasal mucosa, bleeding, dry itchy skin, dry eyes, especially allergic and dry patients, contact lenses should not be used or should not wear contact lenses during the application of this product. 2.Teratogenic effects Animal experiments have proved that oral administration of isotretinoin can lead to developmental malformations, miscarriage and stillbirth. The administration of isotretinoin in the early stage of fetal organ formation can lead to abnormal development of central nervous system and cardiovascular system; the administration of isotretinoin in late pregnancy can lead to fetal limb shortage and urinary system defects. Therefore, when isotretinoin is used clinically, women of childbearing age should be required to take effective contraceptive measures in the month before and during treatment, and to have children only six months after the end of treatment. 3. Effects on bones Long-term application of isotretinoin can cause bone hypertrophy, tendon ligament calcification, osteoporosis and epiphyseal atresia, thus affecting the growth of children and adolescents. Bone hypertrophy and tendon ligament calcification are the most common, and their incidence is related to the dose and duration of medication. Bone hypertrophy can be detected in about 10% of patients when isotretinoin is administered orally at a dose of 1 to 2 mg per kg of body weight per day and for a course of 4 to 5 months for the treatment of acne, so isotretinoin should be avoided with glucocorticoids and other retinoids (including vitamin A). The course of treatment with isotretinoin should not be too long, and when the condition improves significantly, use the maintenance amount or change to other drugs with less adverse reactions to consolidate the treatment, long-term use of isotretinoin patients can be X-rayed regularly. The patient with long-term use of isotretinoin can have regular X-ray examination. Usually eat more calcium-rich food such as milk, pork ribs soup, seafood, etc. Patients with osteoporosis can be given calcium supplementation. 4, the effect on mental activity Some literature reports from 1982 since isotretinoin marketed to May 2000, the U.S. Food and Drug Administration (FDA) has reported 431 cases of mental abnormalities after taking isotretinoin, of which 37 patients committed suicide, 110 patients appeared depressed, suicidal thoughts or suicidal tendencies and hospitalized, 284 patients depressed but not hospitalized. The effect of oral isotretinoin on psychiatric activity correlated with the duration of drug use; discontinuation of the drug or psychiatric treatment resulted in a reduction in symptoms, and reintroduction of the drug resulted in the appearance or worsening of symptoms. Since acne is a disfiguring disease, the facial rash brings great mental stress to the patient’s life, study, work and social life, so some scholars believe that acne is a psychosomatic disease, and there are also a large number of reports that acne itself can cause depression and worry to varying degrees, and even suicidal tendencies and suicidal behavior. Therefore, the mental abnormalities triggered by oral isotretinoin can only indicate a certain correlation with isotretinoin without a clear causal relationship. However, clinicians should be alert to the possibility of psychotic depression with isotretinoin. Patients who already have clear mental depression should avoid treatment with this drug. 5, neuromuscular adverse reactions Foreign literature reports oral isotretinoin can cause headache, dizziness, drowsiness, myalgia, blood creatine kinase (CK) elevation, it is recommended that patients who usually have muscle weakness or blood creatine kinase (CK) elevation, should avoid using or reduce the amount of use, patients with muscle symptoms should avoid strenuous exercise. 6, abnormal laboratory tests Oral isotretinoin can cause an increase in total cholesterol and triglyceride levels. Patients with hyperlipidemia, obesity, and diabetes should avoid using isotretinoin as much as possible.