In the treatment of patients with rheumatic immune diseases, doctors often use a drug called “methotrexate”. When given this drug, which sounds very awkward, many patients are full of doubts – what is it, does it affect their health, and what are the contraindications during taking it? Some patients may say, “Isn’t methotrexate a chemotherapy drug and can it be used for rheumatological diseases? Now let me answer your questions. Methotrexate has been used in rheumatological diseases for three or four decades. The mechanism of action of methotrexate has also been studied clearly, and its safety and effectiveness have been determined. The main effects of methotrexate are: anti-inflammatory and immunosuppressive. It mainly interferes with intracellular folic acid synthesis, which is the raw material for intracellular DNA and RNA synthesis, and when intracellular DNA and RNA synthesis is insufficient, cell growth will be affected. Therefore, methotrexate can control cell growth, especially for those cells that grow rapidly, and it has little effect on those cells that are basically stable in growth. The immune system of patients with rheumatologic diseases is abnormally activated, and some bad immune cells proliferate in the body, causing an immune inflammatory response that leads to inflammation and damage to body organs. Methotrexate can inhibit the growth of these abnormal cells and reduce the damage caused by the immune reaction. Because methotrexate has a small effect on cells that are basically stable in growth, as long as the dose is properly controlled, it generally does not have a major impact on the body. It is worth mentioning that methotrexate is also often used in tumor patients. Because the tumor cells in tumor patients are also growing uncontrollably and indiscriminately, the application of methotrexate can kill these cells and achieve the effect of tumor treatment. Therefore, many patients may think that methotrexate is a chemotherapy drug and an anti-tumor drug, and thus become fearful. However, there is no need to worry too much because immune cells are easier to be removed than tumor cells, so the dose of methotrexate applied in rheumatologic diseases is very small, generally less than 1/10 of the anti-tumor dose. We usually do not feel uncomfortable when applying such a small dose. Methotrexate is divided into tablets and injections. Generally speaking, oral tablets can be taken once a week, which is very convenient to use. Methotrexate is inexpensive, only 20 cents for 1 pill, and the cost for 1 year is only a few dozen dollars. Some patients who experience gastrointestinal discomfort after taking the drug can switch to the use of injections to reduce gastrointestinal reactions. Because methotrexate inhibits the body’s synthesis of folic acid, we need to take some folic acid supplements while taking methotrexate. Usually, we take folic acid the day after using methotrexate, which can reduce the side effects of methotrexate. What are the side effects of methotrexate, and what do we need to pay attention to during the use of the drug? The most common reactions during methotrexate administration are nausea and abdominal pain, but they are generally mild and do not affect continued use. If the symptoms are obvious, the dosage can be reduced or changed to injections to reduce gastrointestinal irritation. Also while taking methotrexate, your doctor will instruct you that you need to have regular blood tests to review your blood work, liver and kidney function. This is because sometimes patients do not have any special discomfort after taking the medication, but the indicators of blood sampling have already shown problems, and the doctor can detect the problems early through the examination at this time. In general, after adjusting the medication, the abnormal indicators can return to normal and methotrexate can be continued to be used. Some other common side effects of methotrexate are hair loss and inflammation of the mouth, which are generally mild and do not affect continued use. In addition, methotrexate is an immunosuppressant, and the body’s resistance may be reduced during the period of taking the drug, so more attention should be paid to not staying up late, getting cold water, and adding clothes in time when the weather changes. You should also avoid spicy and irritating foods to avoid aggravating inflammation. Methotrexate is easy to use, inexpensive, safe and effective, and its application in rheumatic immune diseases has become very mature. It can be used in rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis and many other rheumatic immune diseases and has become the preferred basic drug for rheumatic immune diseases. You should not refuse to take it because you are afraid of the dense medication reminders on the drug manual, and you should not take it upon yourself to increase or decrease the dosage. If you use methotrexate under the guidance of a rheumatologist, you can be cured safely and without toxicity.