Indications For severe acne, especially for nodular cystic acne, but also for dense whiteheads and hair red furunculosis. Dosage and Administration The dose should vary from 0.1 to 1(mg/kg)/day, with a recommended starting dose of 10mg daily. The drug is fat-soluble and can be taken with meals to promote absorption. 2 weeks after treatment, the dose can be adjusted according to clinical effects and adverse reactions as appropriate. 8-12 weeks is a course of treatment, and the drug can be stopped for 8 weeks between courses. Common side effects 1. Common side effects include dryness, itching, pain, increased skin fragility, palmoplantar peeling, petechiae, and secondary infections; 2. conjunctivitis, corneal clouding in severe cases, visual impairment, optic papilledema, headache, dizziness, psychiatric symptoms, depression, benign brain pressure increase; 3. hair thinning, nail softening; 4. osteoporosis, muscle weakness, pain, gastrointestinal 5. Pregnancy may lead to spontaneous abortion and fetal development malformation; 6. Laboratory tests may cause rapid blood sedimentation, elevated liver enzymes, elevated blood lipids, elevated blood glucose and decreased platelets. Most of the above side effects are reversible and can be recovered gradually after stopping the drug. The severity of the side effects is related to the dose, duration of treatment and individual tolerance of the drug. Mild adverse reactions do not need to stop the drug, or reduce the amount of use, serious adverse reactions should immediately stop the drug, and go to the hospital by the doctor for appropriate treatment. Tips for use 1. Avoid drinking alcohol and oral intake of drugs that affect the liver during the medication period. 2, avoid sun exposure and other strong light exposure, avoid facing the computer for a long time. 3.Avoid external facial cleanser, hot water washing, forceful face rubbing, avoid perming, appropriate external water, lotion, cream and other hydration-based cosmetics. 4, the mouth and lips dry and cracked can be topical topical lip balm, multiple times a day. Drink more water every day, at least two liters. 5.Contraception within one year of stopping the drug.