Methotrexate is certainly effective in the treatment of psoriasis patients and is a commonly used drug for the treatment of psoriasis. It can be used for erythrodermic, arthritic, pustular and generalized recalcitrant psoriasis of the common type. It is not recommended for patients with abnormal liver and kidney function, pregnancy, severe anemia, leukopenia, peptic ulcer and active infection. The dosing method, usually 7.5-15mg per week, can be taken orally or by intravenous drip, and the dose can be gradually reduced and stopped after a period of maintenance. The blood routine, liver function and kidney function should be reviewed regularly every week, because the therapeutic and toxic amounts of this drug are very close to each other, and long-term use can cause fibrosis of the liver and cirrhosis of the liver. You can take folic acid tablets while taking methotrexate to reduce the gastrointestinal reaction of the drug.